Auto merge of #136332 - jhpratt:rollup-aa69d0e, r=jhpratt

Rollup of 9 pull requests

Successful merges:

 - #132156 (When encountering unexpected closure return type, point at return type/expression)
 - #133429 (Autodiff Upstreaming - rustc_codegen_ssa, rustc_middle)
 - #136281 (`rustc_hir_analysis` cleanups)
 - #136297 (Fix a typo in profile-guided-optimization.md)
 - #136300 (atomic: extend compare_and_swap migration docs)
 - #136310 (normalize `*.long-type.txt` paths for compare-mode tests)
 - #136312 (Disable `overflow_delimited_expr` in edition 2024)
 - #136313 (Filter out RPITITs when suggesting unconstrained assoc type on too many generics)
 - #136323 (Fix a typo in conventions.md)

r? `@ghost`
`@rustbot` modify labels: rollup

Cargo.lock

@@ -4234,6 +4234,7 @@ name = "rustc_monomorphize"
 version = "0.0.0"
 dependencies = [
  "rustc_abi",
+ "rustc_ast",
  "rustc_attr_parsing",
  "rustc_data_structures",
  "rustc_errors",
@@ -4243,6 +4244,7 @@ dependencies = [
  "rustc_middle",
  "rustc_session",
  "rustc_span",
+ "rustc_symbol_mangling",
  "rustc_target",
  "serde",
  "serde_json",

compiler/rustc_ast/src/expand/autodiff_attrs.rs

@@ -79,6 +79,7 @@ pub struct AutoDiffItem {
     pub target: String,
     pub attrs: AutoDiffAttrs,
 }
+
 #[derive(Clone, Eq, PartialEq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub struct AutoDiffAttrs {
     /// Conceptually either forward or reverse mode AD, as described in various autodiff papers and
@@ -231,7 +232,7 @@ impl AutoDiffAttrs {
         self.ret_activity == DiffActivity::ActiveOnly
     }
 
-    pub fn error() -> Self {
+    pub const fn error() -> Self {
         AutoDiffAttrs {
             mode: DiffMode::Error,
             ret_activity: DiffActivity::None,

compiler/rustc_codegen_llvm/src/builder/autodiff.rs

@@ -62,8 +62,8 @@ fn generate_enzyme_call<'ll>(
     // add outer_fn name to ad_name to make it unique, in case users apply autodiff to multiple
     // functions. Unwrap will only panic, if LLVM gave us an invalid string.
     let name = llvm::get_value_name(outer_fn);
-    let outer_fn_name = std::ffi::CStr::from_bytes_with_nul(name).unwrap().to_str().unwrap();
+    let outer_fn_name = std::str::from_utf8(name).unwrap();
-    ad_name.push_str(outer_fn_name.to_string().as_str());
+    ad_name.push_str(outer_fn_name);
 
     // Let us assume the user wrote the following function square:
     //
@@ -255,14 +255,14 @@ fn generate_enzyme_call<'ll>(
             // have no debug info to copy, which would then be ok.
             trace!("no dbg info");
         }
-        // Now that we copied the metadata, get rid of dummy code.
-        llvm::LLVMRustEraseInstBefore(entry, last_inst);
-        llvm::LLVMRustEraseInstFromParent(last_inst);
 
-        if cx.val_ty(outer_fn) != cx.type_void() {
+        // Now that we copied the metadata, get rid of dummy code.
-            builder.ret(call);
+        llvm::LLVMRustEraseInstUntilInclusive(entry, last_inst);
-        } else {
+
+        if cx.val_ty(call) == cx.type_void() {
             builder.ret_void();
+        } else {
+            builder.ret(call);
         }
 
         // Let's crash in case that we messed something up above and generated invalid IR.

compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs

@@ -298,7 +298,7 @@ struct UsageSets<'tcx> {
 /// Prepare sets of definitions that are relevant to deciding whether something
 /// is an "unused function" for coverage purposes.
 fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> {
-    let MonoItemPartitions { all_mono_items, codegen_units } =
+    let MonoItemPartitions { all_mono_items, codegen_units, .. } =
         tcx.collect_and_partition_mono_items(());
 
     // Obtain a MIR body for each function participating in codegen, via an

compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs

@@ -7,11 +7,13 @@ use crate::llvm::Bool;
 extern "C" {
     // Enzyme
     pub fn LLVMRustHasMetadata(I: &Value, KindID: c_uint) -> bool;
-    pub fn LLVMRustEraseInstBefore(BB: &BasicBlock, I: &Value);
+    pub fn LLVMRustEraseInstUntilInclusive(BB: &BasicBlock, I: &Value);
     pub fn LLVMRustGetLastInstruction<'a>(BB: &BasicBlock) -> Option<&'a Value>;
     pub fn LLVMRustDIGetInstMetadata(I: &Value) -> Option<&Metadata>;
     pub fn LLVMRustEraseInstFromParent(V: &Value);
     pub fn LLVMRustGetTerminator<'a>(B: &BasicBlock) -> &'a Value;
+    pub fn LLVMDumpModule(M: &Module);
+    pub fn LLVMDumpValue(V: &Value);
     pub fn LLVMRustVerifyFunction(V: &Value, action: LLVMRustVerifierFailureAction) -> Bool;
 
     pub fn LLVMGetFunctionCallConv(F: &Value) -> c_uint;

compiler/rustc_codegen_ssa/messages.ftl

@@ -16,6 +16,8 @@ codegen_ssa_archive_build_failure = failed to build archive at `{$path}`: {$erro
 
 codegen_ssa_atomic_compare_exchange = Atomic compare-exchange intrinsic missing failure memory ordering
 
+codegen_ssa_autodiff_without_lto = using the autodiff feature requires using fat-lto
+
 codegen_ssa_binary_output_to_tty = option `-o` or `--emit` is used to write binary output type `{$shorthand}` to stdout, but stdout is a tty
 
 codegen_ssa_cgu_not_recorded =

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -7,6 +7,7 @@ use std::sync::mpsc::{Receiver, Sender, channel};
 use std::{fs, io, mem, str, thread};
 
 use rustc_ast::attr;
+use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::jobserver::{self, Acquired};
 use rustc_data_structures::memmap::Mmap;
@@ -40,7 +41,7 @@ use tracing::debug;
 use super::link::{self, ensure_removed};
 use super::lto::{self, SerializedModule};
 use super::symbol_export::symbol_name_for_instance_in_crate;
-use crate::errors::ErrorCreatingRemarkDir;
+use crate::errors::{AutodiffWithoutLto, ErrorCreatingRemarkDir};
 use crate::traits::*;
 use crate::{
     CachedModuleCodegen, CodegenResults, CompiledModule, CrateInfo, ModuleCodegen, ModuleKind,
@@ -118,6 +119,7 @@ pub struct ModuleConfig {
     pub merge_functions: bool,
     pub emit_lifetime_markers: bool,
     pub llvm_plugins: Vec<String>,
+    pub autodiff: Vec<config::AutoDiff>,
 }
 
 impl ModuleConfig {
@@ -266,6 +268,7 @@ impl ModuleConfig {
 
             emit_lifetime_markers: sess.emit_lifetime_markers(),
             llvm_plugins: if_regular!(sess.opts.unstable_opts.llvm_plugins.clone(), vec![]),
+            autodiff: if_regular!(sess.opts.unstable_opts.autodiff.clone(), vec![]),
         }
     }
 
@@ -389,6 +392,7 @@ impl<B: WriteBackendMethods> CodegenContext<B> {
 
 fn generate_lto_work<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
+    autodiff: Vec<AutoDiffItem>,
     needs_fat_lto: Vec<FatLtoInput<B>>,
     needs_thin_lto: Vec<(String, B::ThinBuffer)>,
     import_only_modules: Vec<(SerializedModule<B::ModuleBuffer>, WorkProduct)>,
@@ -397,11 +401,19 @@ fn generate_lto_work<B: ExtraBackendMethods>(
 
     if !needs_fat_lto.is_empty() {
         assert!(needs_thin_lto.is_empty());
-        let module =
+        let mut module =
             B::run_fat_lto(cgcx, needs_fat_lto, import_only_modules).unwrap_or_else(|e| e.raise());
+        if cgcx.lto == Lto::Fat {
+            let config = cgcx.config(ModuleKind::Regular);
+            module = unsafe { module.autodiff(cgcx, autodiff, config).unwrap() };
+        }
         // We are adding a single work item, so the cost doesn't matter.
         vec![(WorkItem::LTO(module), 0)]
     } else {
+        if !autodiff.is_empty() {
+            let dcx = cgcx.create_dcx();
+            dcx.handle().emit_fatal(AutodiffWithoutLto {});
+        }
         assert!(needs_fat_lto.is_empty());
         let (lto_modules, copy_jobs) = B::run_thin_lto(cgcx, needs_thin_lto, import_only_modules)
             .unwrap_or_else(|e| e.raise());
@@ -1021,6 +1033,9 @@ pub(crate) enum Message<B: WriteBackendMethods> {
     /// Sent from a backend worker thread.
     WorkItem { result: Result<WorkItemResult<B>, Option<WorkerFatalError>>, worker_id: usize },
 
+    /// A vector containing all the AutoDiff tasks that we have to pass to Enzyme.
+    AddAutoDiffItems(Vec<AutoDiffItem>),
+
     /// The frontend has finished generating something (backend IR or a
     /// post-LTO artifact) for a codegen unit, and it should be passed to the
     /// backend. Sent from the main thread.
@@ -1348,6 +1363,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
 
         // This is where we collect codegen units that have gone all the way
         // through codegen and LLVM.
+        let mut autodiff_items = Vec::new();
         let mut compiled_modules = vec![];
         let mut compiled_allocator_module = None;
         let mut needs_link = Vec::new();
@@ -1459,9 +1475,13 @@ fn start_executing_work<B: ExtraBackendMethods>(
                     let needs_thin_lto = mem::take(&mut needs_thin_lto);
                     let import_only_modules = mem::take(&mut lto_import_only_modules);
 
-                    for (work, cost) in
+                    for (work, cost) in generate_lto_work(
-                        generate_lto_work(&cgcx, needs_fat_lto, needs_thin_lto, import_only_modules)
+                        &cgcx,
-                    {
+                        autodiff_items.clone(),
+                        needs_fat_lto,
+                        needs_thin_lto,
+                        import_only_modules,
+                    ) {
                         let insertion_index = work_items
                             .binary_search_by_key(&cost, |&(_, cost)| cost)
                             .unwrap_or_else(|e| e);
@@ -1596,6 +1616,10 @@ fn start_executing_work<B: ExtraBackendMethods>(
                     main_thread_state = MainThreadState::Idle;
                 }
 
+                Message::AddAutoDiffItems(mut items) => {
+                    autodiff_items.append(&mut items);
+                }
+
                 Message::CodegenComplete => {
                     if codegen_state != Aborted {
                         codegen_state = Completed;
@@ -2070,6 +2094,10 @@ impl<B: ExtraBackendMethods> OngoingCodegen<B> {
         drop(self.coordinator.sender.send(Box::new(Message::CodegenComplete::<B>)));
     }
 
+    pub(crate) fn submit_autodiff_items(&self, items: Vec<AutoDiffItem>) {
+        drop(self.coordinator.sender.send(Box::new(Message::<B>::AddAutoDiffItems(items))));
+    }
+
     pub(crate) fn check_for_errors(&self, sess: &Session) {
         self.shared_emitter_main.check(sess, false);
     }

compiler/rustc_codegen_ssa/src/base.rs

@@ -18,7 +18,7 @@ use rustc_middle::middle::debugger_visualizer::{DebuggerVisualizerFile, Debugger
 use rustc_middle::middle::exported_symbols::SymbolExportKind;
 use rustc_middle::middle::{exported_symbols, lang_items};
 use rustc_middle::mir::BinOp;
-use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
+use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem, MonoItemPartitions};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutOf, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
@@ -623,7 +623,9 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
 
     // Run the monomorphization collector and partition the collected items into
     // codegen units.
-    let codegen_units = tcx.collect_and_partition_mono_items(()).codegen_units;
+    let MonoItemPartitions { codegen_units, autodiff_items, .. } =
+        tcx.collect_and_partition_mono_items(());
+    let autodiff_fncs = autodiff_items.to_vec();
 
     // Force all codegen_unit queries so they are already either red or green
     // when compile_codegen_unit accesses them. We are not able to re-execute
@@ -694,6 +696,10 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         );
     }
 
+    if !autodiff_fncs.is_empty() {
+        ongoing_codegen.submit_autodiff_items(autodiff_fncs);
+    }
+
     // For better throughput during parallel processing by LLVM, we used to sort
     // CGUs largest to smallest. This would lead to better thread utilization
     // by, for example, preventing a large CGU from being processed last and

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -1,5 +1,10 @@
+use std::str::FromStr;
+
 use rustc_ast::attr::list_contains_name;
-use rustc_ast::{MetaItemInner, attr};
+use rustc_ast::expand::autodiff_attrs::{
+    AutoDiffAttrs, DiffActivity, DiffMode, valid_input_activity, valid_ret_activity,
+};
+use rustc_ast::{MetaItem, MetaItemInner, attr};
 use rustc_attr_parsing::{InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::codes::*;
@@ -13,6 +18,7 @@ use rustc_middle::middle::codegen_fn_attrs::{
 };
 use rustc_middle::mir::mono::Linkage;
 use rustc_middle::query::Providers;
+use rustc_middle::span_bug;
 use rustc_middle::ty::{self as ty, TyCtxt};
 use rustc_session::parse::feature_err;
 use rustc_session::{Session, lint};
@@ -65,6 +71,13 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
         codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
     }
 
+    // If our rustc version supports autodiff/enzyme, then we call our handler
+    // to check for any `#[rustc_autodiff(...)]` attributes.
+    if cfg!(llvm_enzyme) {
+        let ad = autodiff_attrs(tcx, did.into());
+        codegen_fn_attrs.autodiff_item = ad;
+    }
+
     // When `no_builtins` is applied at the crate level, we should add the
     // `no-builtins` attribute to each function to ensure it takes effect in LTO.
     let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
@@ -856,6 +869,109 @@ impl<'a> MixedExportNameAndNoMangleState<'a> {
     }
 }
 
+/// We now check the #\[rustc_autodiff\] attributes which we generated from the #[autodiff(...)]
+/// macros. There are two forms. The pure one without args to mark primal functions (the functions
+/// being differentiated). The other form is #[rustc_autodiff(Mode, ActivityList)] on top of the
+/// placeholder functions. We wrote the rustc_autodiff attributes ourself, so this should never
+/// panic, unless we introduced a bug when parsing the autodiff macro.
+fn autodiff_attrs(tcx: TyCtxt<'_>, id: DefId) -> Option<AutoDiffAttrs> {
+    let attrs = tcx.get_attrs(id, sym::rustc_autodiff);
+
+    let attrs =
+        attrs.filter(|attr| attr.name_or_empty() == sym::rustc_autodiff).collect::<Vec<_>>();
+
+    // check for exactly one autodiff attribute on placeholder functions.
+    // There should only be one, since we generate a new placeholder per ad macro.
+    // FIXME(ZuseZ4): re-enable this check. Currently we add multiple, which doesn't cause harm but
+    // looks strange e.g. under cargo-expand.
+    let attr = match &attrs[..] {
+        [] => return None,
+        [attr] => attr,
+        // These two attributes are the same and unfortunately duplicated due to a previous bug.
+        [attr, _attr2] => attr,
+        _ => {
+            //FIXME(ZuseZ4): Once we fixed our parser, we should also prohibit the two-attribute
+            //branch above.
+            span_bug!(attrs[1].span, "cg_ssa: rustc_autodiff should only exist once per source");
+        }
+    };
+
+    let list = attr.meta_item_list().unwrap_or_default();
+
+    // empty autodiff attribute macros (i.e. `#[autodiff]`) are used to mark source functions
+    if list.is_empty() {
+        return Some(AutoDiffAttrs::source());
+    }
+
+    let [mode, input_activities @ .., ret_activity] = &list[..] else {
+        span_bug!(attr.span, "rustc_autodiff attribute must contain mode and activities");
+    };
+    let mode = if let MetaItemInner::MetaItem(MetaItem { path: ref p1, .. }) = mode {
+        p1.segments.first().unwrap().ident
+    } else {
+        span_bug!(attr.span, "rustc_autodiff attribute must contain mode");
+    };
+
+    // parse mode
+    let mode = match mode.as_str() {
+        "Forward" => DiffMode::Forward,
+        "Reverse" => DiffMode::Reverse,
+        "ForwardFirst" => DiffMode::ForwardFirst,
+        "ReverseFirst" => DiffMode::ReverseFirst,
+        _ => {
+            span_bug!(mode.span, "rustc_autodiff attribute contains invalid mode");
+        }
+    };
+
+    // First read the ret symbol from the attribute
+    let ret_symbol = if let MetaItemInner::MetaItem(MetaItem { path: ref p1, .. }) = ret_activity {
+        p1.segments.first().unwrap().ident
+    } else {
+        span_bug!(attr.span, "rustc_autodiff attribute must contain the return activity");
+    };
+
+    // Then parse it into an actual DiffActivity
+    let Ok(ret_activity) = DiffActivity::from_str(ret_symbol.as_str()) else {
+        span_bug!(ret_symbol.span, "invalid return activity");
+    };
+
+    // Now parse all the intermediate (input) activities
+    let mut arg_activities: Vec<DiffActivity> = vec![];
+    for arg in input_activities {
+        let arg_symbol = if let MetaItemInner::MetaItem(MetaItem { path: ref p2, .. }) = arg {
+            match p2.segments.first() {
+                Some(x) => x.ident,
+                None => {
+                    span_bug!(
+                        arg.span(),
+                        "rustc_autodiff attribute must contain the input activity"
+                    );
+                }
+            }
+        } else {
+            span_bug!(arg.span(), "rustc_autodiff attribute must contain the input activity");
+        };
+
+        match DiffActivity::from_str(arg_symbol.as_str()) {
+            Ok(arg_activity) => arg_activities.push(arg_activity),
+            Err(_) => {
+                span_bug!(arg_symbol.span, "invalid input activity");
+            }
+        }
+    }
+
+    for &input in &arg_activities {
+        if !valid_input_activity(mode, input) {
+            span_bug!(attr.span, "Invalid input activity {} for {} mode", input, mode);
+        }
+    }
+    if !valid_ret_activity(mode, ret_activity) {
+        span_bug!(attr.span, "Invalid return activity {} for {} mode", ret_activity, mode);
+    }
+
+    Some(AutoDiffAttrs { mode, ret_activity, input_activity: arg_activities })
+}
+
 pub(crate) fn provide(providers: &mut Providers) {
     *providers = Providers { codegen_fn_attrs, should_inherit_track_caller, ..*providers };
 }

compiler/rustc_codegen_ssa/src/errors.rs

@@ -39,6 +39,10 @@ pub(crate) struct CguNotRecorded<'a> {
     pub cgu_name: &'a str,
 }
 
+#[derive(Diagnostic)]
+#[diag(codegen_ssa_autodiff_without_lto)]
+pub struct AutodiffWithoutLto;
+
 #[derive(Diagnostic)]
 #[diag(codegen_ssa_unknown_reuse_kind)]
 pub(crate) struct UnknownReuseKind {

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -424,12 +424,12 @@ fn compare_method_predicate_entailment<'tcx>(
     Ok(())
 }
 
-struct RemapLateParam<'a, 'tcx> {
+struct RemapLateParam<'tcx> {
     tcx: TyCtxt<'tcx>,
-    mapping: &'a FxIndexMap<ty::LateParamRegionKind, ty::LateParamRegionKind>,
+    mapping: FxIndexMap<ty::LateParamRegionKind, ty::LateParamRegionKind>,
 }
 
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateParam<'_, 'tcx> {
+impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RemapLateParam<'tcx> {
     fn cx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
@@ -653,6 +653,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
                 }))),
                 terr,
                 false,
+                None,
             );
             return Err(diag.emit());
         }
@@ -1070,6 +1071,7 @@ fn report_trait_method_mismatch<'tcx>(
         }))),
         terr,
         false,
+        None,
     );
 
     diag.emit()
@@ -1862,6 +1864,7 @@ fn compare_const_predicate_entailment<'tcx>(
             }))),
             terr,
             false,
+            None,
         );
         return Err(diag.emit());
     };

compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs

@@ -299,8 +299,7 @@ fn report_mismatched_rpitit_signature<'tcx>(
     })
     .collect();
 
-    let mut return_ty =
+    let mut return_ty = trait_m_sig.output().fold_with(&mut super::RemapLateParam { tcx, mapping });
-        trait_m_sig.output().fold_with(&mut super::RemapLateParam { tcx, mapping: &mapping });
 
     if tcx.asyncness(impl_m_def_id).is_async() && tcx.asyncness(trait_m_def_id).is_async() {
         let ty::Alias(ty::Projection, future_ty) = return_ty.kind() else {

compiler/rustc_hir_analysis/src/check/dropck.rs

@@ -1,7 +1,3 @@
-// FIXME(@lcnr): Move this module out of `rustc_hir_analysis`.
-//
-// We don't do any drop checking during hir typeck.
-
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::codes::*;
 use rustc_errors::{ErrorGuaranteed, struct_span_code_err};
@@ -32,7 +28,10 @@ use crate::hir::def_id::{DefId, LocalDefId};
 ///    struct/enum definition for the nominal type itself (i.e.
 ///    cannot do `struct S<T>; impl<T:Clone> Drop for S<T> { ... }`).
 ///
-pub fn check_drop_impl(tcx: TyCtxt<'_>, drop_impl_did: DefId) -> Result<(), ErrorGuaranteed> {
+pub(crate) fn check_drop_impl(
+    tcx: TyCtxt<'_>,
+    drop_impl_did: DefId,
+) -> Result<(), ErrorGuaranteed> {
     match tcx.impl_polarity(drop_impl_did) {
         ty::ImplPolarity::Positive => {}
         ty::ImplPolarity::Negative => {

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -199,7 +199,8 @@ pub fn check_intrinsic_type(
         let split: Vec<&str> = name_str.split('_').collect();
         assert!(split.len() >= 2, "Atomic intrinsic in an incorrect format");
 
-        //We only care about the operation here
+        // Each atomic op has variants with different suffixes (`_seq_cst`, `_acquire`, etc.). Use
+        // string ops to strip the suffixes, because the variants all get the same treatment here.
         let (n_tps, inputs, output) = match split[1] {
             "cxchg" | "cxchgweak" => (
                 1,

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -455,18 +455,14 @@ fn fn_sig_suggestion<'tcx>(
     let mut output = sig.output();
 
     let asyncness = if tcx.asyncness(assoc.def_id).is_async() {
-        output = if let ty::Alias(_, alias_ty) = *output.kind() {
+        output = if let ty::Alias(_, alias_ty) = *output.kind()
-            tcx.explicit_item_self_bounds(alias_ty.def_id)
+            && let Some(output) = tcx
+                .explicit_item_self_bounds(alias_ty.def_id)
                 .iter_instantiated_copied(tcx, alias_ty.args)
                 .find_map(|(bound, _)| {
                     bound.as_projection_clause()?.no_bound_vars()?.term.as_type()
-                })
+                }) {
-                .unwrap_or_else(|| {
+            output
-                    span_bug!(
-                        ident.span,
-                        "expected async fn to have `impl Future` output, but it returns {output}"
-                    )
-                })
         } else {
             span_bug!(
                 ident.span,
@@ -649,6 +645,7 @@ pub fn check_function_signature<'tcx>(
                 }))),
                 err,
                 false,
+                None,
             );
             return Err(diag.emit());
         }

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -2267,14 +2267,12 @@ impl<'tcx> WfCheckingCtxt<'_, 'tcx> {
 
 fn check_mod_type_wf(tcx: TyCtxt<'_>, module: LocalModDefId) -> Result<(), ErrorGuaranteed> {
     let items = tcx.hir_module_items(module);
-    let mut res = items.par_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id));
+    let res = items
-    res =
+        .par_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id))
-        res.and(items.par_impl_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)));
+        .and(items.par_impl_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)))
-    res =
+        .and(items.par_trait_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)))
-        res.and(items.par_trait_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)));
+        .and(items.par_foreign_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)))
-    res = res
+        .and(items.par_opaques(|item| tcx.ensure().check_well_formed(item)));
-        .and(items.par_foreign_items(|item| tcx.ensure().check_well_formed(item.owner_id.def_id)));
-    res = res.and(items.par_opaques(|item| tcx.ensure().check_well_formed(item)));
     if module == LocalModDefId::CRATE_DEF_ID {
         super::entry::check_for_entry_fn(tcx);
     }

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -404,17 +404,12 @@ pub(crate) fn coerce_unsized_info<'tcx>(
             check_mutbl(mt_a, mt_b, &|ty| Ty::new_imm_ref(tcx, r_b, ty))
         }
 
-        (&ty::Ref(_, ty_a, mutbl_a), &ty::RawPtr(ty_b, mutbl_b)) => check_mutbl(
+        (&ty::Ref(_, ty_a, mutbl_a), &ty::RawPtr(ty_b, mutbl_b))
-            ty::TypeAndMut { ty: ty_a, mutbl: mutbl_a },
+        | (&ty::RawPtr(ty_a, mutbl_a), &ty::RawPtr(ty_b, mutbl_b)) => {
-            ty::TypeAndMut { ty: ty_b, mutbl: mutbl_b },
+            let mt_a = ty::TypeAndMut { ty: ty_a, mutbl: mutbl_a };
-            &|ty| Ty::new_imm_ptr(tcx, ty),
+            let mt_b = ty::TypeAndMut { ty: ty_b, mutbl: mutbl_b };
-        ),
+            check_mutbl(mt_a, mt_b, &|ty| Ty::new_imm_ptr(tcx, ty))
-
+        }
-        (&ty::RawPtr(ty_a, mutbl_a), &ty::RawPtr(ty_b, mutbl_b)) => check_mutbl(
-            ty::TypeAndMut { ty: ty_a, mutbl: mutbl_a },
-            ty::TypeAndMut { ty: ty_b, mutbl: mutbl_b },
-            &|ty| Ty::new_imm_ptr(tcx, ty),
-        ),
 
         (&ty::Adt(def_a, args_a), &ty::Adt(def_b, args_b))
             if def_a.is_struct() && def_b.is_struct() =>

compiler/rustc_hir_analysis/src/coherence/mod.rs

@@ -158,12 +158,12 @@ fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) -> Result<(), ErrorGuaranteed>
         let trait_ref = trait_header.trait_ref.instantiate_identity();
         let trait_def = tcx.trait_def(trait_ref.def_id);
 
-        res = res.and(check_impl(tcx, impl_def_id, trait_ref, trait_def));
+        res = res
-        res = res.and(check_object_overlap(tcx, impl_def_id, trait_ref));
+            .and(check_impl(tcx, impl_def_id, trait_ref, trait_def))
-
+            .and(check_object_overlap(tcx, impl_def_id, trait_ref))
-        res = res.and(unsafety::check_item(tcx, impl_def_id, trait_header, trait_def));
+            .and(unsafety::check_item(tcx, impl_def_id, trait_header, trait_def))
-        res = res.and(tcx.ensure().orphan_check_impl(impl_def_id));
+            .and(tcx.ensure().orphan_check_impl(impl_def_id))
-        res = res.and(builtin::check_trait(tcx, def_id, impl_def_id, trait_header));
+            .and(builtin::check_trait(tcx, def_id, impl_def_id, trait_header));
     }
 
     res

compiler/rustc_hir_analysis/src/collect.rs

@@ -57,7 +57,7 @@ mod type_of;
 
 ///////////////////////////////////////////////////////////////////////////
 
-pub fn provide(providers: &mut Providers) {
+pub(crate) fn provide(providers: &mut Providers) {
     resolve_bound_vars::provide(providers);
     *providers = Providers {
         type_of: type_of::type_of,
@@ -122,7 +122,7 @@ pub fn provide(providers: &mut Providers) {
 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
 /// `probe_ty_param_bounds` requests, drawing the information from
 /// the HIR (`hir::Generics`), recursively.
-pub struct ItemCtxt<'tcx> {
+pub(crate) struct ItemCtxt<'tcx> {
     tcx: TyCtxt<'tcx>,
     item_def_id: LocalDefId,
     tainted_by_errors: Cell<Option<ErrorGuaranteed>>,
@@ -148,7 +148,7 @@ impl<'v> Visitor<'v> for HirPlaceholderCollector {
     }
 }
 
-pub struct CollectItemTypesVisitor<'tcx> {
+pub(crate) struct CollectItemTypesVisitor<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 }
 
@@ -364,19 +364,19 @@ fn bad_placeholder<'cx, 'tcx>(
 }
 
 impl<'tcx> ItemCtxt<'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx> {
+    pub(crate) fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx> {
         ItemCtxt { tcx, item_def_id, tainted_by_errors: Cell::new(None) }
     }
 
-    pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
+    pub(crate) fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
         self.lowerer().lower_ty(hir_ty)
     }
 
-    pub fn hir_id(&self) -> hir::HirId {
+    pub(crate) fn hir_id(&self) -> hir::HirId {
         self.tcx.local_def_id_to_hir_id(self.item_def_id)
     }
 
-    pub fn node(&self) -> hir::Node<'tcx> {
+    pub(crate) fn node(&self) -> hir::Node<'tcx> {
         self.tcx.hir_node(self.hir_id())
     }
 

compiler/rustc_hir_analysis/src/delegation.rs

@@ -100,213 +100,156 @@ enum InheritanceKind {
     Own,
 }
 
-struct GenericsBuilder<'tcx> {
+fn build_generics<'tcx>(
     tcx: TyCtxt<'tcx>,
     sig_id: DefId,
     parent: Option<DefId>,
     inh_kind: InheritanceKind,
-}
+) -> ty::Generics {
+    let mut own_params = vec![];
 
-impl<'tcx> GenericsBuilder<'tcx> {
+    let sig_generics = tcx.generics_of(sig_id);
-    fn new(tcx: TyCtxt<'tcx>, sig_id: DefId) -> GenericsBuilder<'tcx> {
+    if let InheritanceKind::WithParent(has_self) = inh_kind
-        GenericsBuilder { tcx, sig_id, parent: None, inh_kind: InheritanceKind::WithParent(false) }
+        && let Some(parent_def_id) = sig_generics.parent
+    {
+        let sig_parent_generics = tcx.generics_of(parent_def_id);
+        own_params.append(&mut sig_parent_generics.own_params.clone());
+        if !has_self {
+            own_params.remove(0);
+        }
     }
+    own_params.append(&mut sig_generics.own_params.clone());
 
-    fn with_parent(mut self, parent: DefId) -> Self {
+    // Lifetime parameters must be declared before type and const parameters.
-        self.parent = Some(parent);
+    // Therefore, When delegating from a free function to a associated function,
-        self
+    // generic parameters need to be reordered:
-    }
+    //
+    // trait Trait<'a, A> {
+    //     fn foo<'b, B>(...) {...}
+    // }
+    //
+    // reuse Trait::foo;
+    // desugaring:
+    // fn foo<'a, 'b, This: Trait<'a, A>, A, B>(...) {
+    //     Trait::foo(...)
+    // }
+    own_params.sort_by_key(|key| key.kind.is_ty_or_const());
 
-    fn with_inheritance_kind(mut self, inh_kind: InheritanceKind) -> Self {
+    let param_def_id_to_index =
-        self.inh_kind = inh_kind;
+        own_params.iter().map(|param| (param.def_id, param.index)).collect();
-        self
-    }
 
-    fn build(self) -> ty::Generics {
+    let (parent_count, has_self) = if let Some(def_id) = parent {
-        let mut own_params = vec![];
+        let parent_generics = tcx.generics_of(def_id);
+        let parent_kind = tcx.def_kind(def_id);
+        (parent_generics.count(), parent_kind == DefKind::Trait)
+    } else {
+        (0, false)
+    };
 
-        let sig_generics = self.tcx.generics_of(self.sig_id);
+    for (idx, param) in own_params.iter_mut().enumerate() {
-        if let InheritanceKind::WithParent(has_self) = self.inh_kind
+        param.index = (idx + parent_count) as u32;
-            && let Some(parent_def_id) = sig_generics.parent
+        // FIXME(fn_delegation): Default parameters are not inherited, because they are
+        // not permitted in functions. Therefore, there are 2 options here:
+        //
+        // - We can create non-default generic parameters.
+        // - We can substitute default parameters into the signature.
+        //
+        // At the moment, first option has been selected as the most general.
+        if let ty::GenericParamDefKind::Type { has_default, .. }
+        | ty::GenericParamDefKind::Const { has_default, .. } = &mut param.kind
         {
-            let sig_parent_generics = self.tcx.generics_of(parent_def_id);
+            *has_default = false;
-            own_params.append(&mut sig_parent_generics.own_params.clone());
-            if !has_self {
-                own_params.remove(0);
-            }
         }
-        own_params.append(&mut sig_generics.own_params.clone());
+    }
 
-        // Lifetime parameters must be declared before type and const parameters.
+    ty::Generics {
-        // Therefore, When delegating from a free function to a associated function,
+        parent,
-        // generic parameters need to be reordered:
+        parent_count,
-        //
+        own_params,
-        // trait Trait<'a, A> {
+        param_def_id_to_index,
-        //     fn foo<'b, B>(...) {...}
+        has_self,
-        // }
+        has_late_bound_regions: sig_generics.has_late_bound_regions,
-        //
-        // reuse Trait::foo;
-        // desugaring:
-        // fn foo<'a, 'b, This: Trait<'a, A>, A, B>(...) {
-        //     Trait::foo(...)
-        // }
-        own_params.sort_by_key(|key| key.kind.is_ty_or_const());
-
-        let param_def_id_to_index =
-            own_params.iter().map(|param| (param.def_id, param.index)).collect();
-
-        let (parent_count, has_self) = if let Some(def_id) = self.parent {
-            let parent_generics = self.tcx.generics_of(def_id);
-            let parent_kind = self.tcx.def_kind(def_id);
-            (parent_generics.count(), parent_kind == DefKind::Trait)
-        } else {
-            (0, false)
-        };
-
-        for (idx, param) in own_params.iter_mut().enumerate() {
-            param.index = (idx + parent_count) as u32;
-            // FIXME(fn_delegation): Default parameters are not inherited, because they are
-            // not permitted in functions. Therefore, there are 2 options here:
-            //
-            // - We can create non-default generic parameters.
-            // - We can substitute default parameters into the signature.
-            //
-            // At the moment, first option has been selected as the most general.
-            if let ty::GenericParamDefKind::Type { has_default, .. }
-            | ty::GenericParamDefKind::Const { has_default, .. } = &mut param.kind
-            {
-                *has_default = false;
-            }
-        }
-
-        ty::Generics {
-            parent: self.parent,
-            parent_count,
-            own_params,
-            param_def_id_to_index,
-            has_self,
-            has_late_bound_regions: sig_generics.has_late_bound_regions,
-        }
     }
 }
 
-struct PredicatesBuilder<'tcx> {
+fn build_predicates<'tcx>(
     tcx: TyCtxt<'tcx>,
     sig_id: DefId,
     parent: Option<DefId>,
     inh_kind: InheritanceKind,
     args: ty::GenericArgsRef<'tcx>,
-}
+) -> ty::GenericPredicates<'tcx> {
-
+    struct PredicatesCollector<'tcx> {
-impl<'tcx> PredicatesBuilder<'tcx> {
-    fn new(
         tcx: TyCtxt<'tcx>,
+        preds: Vec<(ty::Clause<'tcx>, Span)>,
         args: ty::GenericArgsRef<'tcx>,
-        sig_id: DefId,
-    ) -> PredicatesBuilder<'tcx> {
-        PredicatesBuilder {
-            tcx,
-            sig_id,
-            parent: None,
-            inh_kind: InheritanceKind::WithParent(false),
-            args,
-        }
     }
 
-    fn with_parent(mut self, parent: DefId) -> Self {
+    impl<'tcx> PredicatesCollector<'tcx> {
-        self.parent = Some(parent);
+        fn new(tcx: TyCtxt<'tcx>, args: ty::GenericArgsRef<'tcx>) -> PredicatesCollector<'tcx> {
-        self
+            PredicatesCollector { tcx, preds: vec![], args }
-    }
-
-    fn with_inheritance_kind(mut self, inh_kind: InheritanceKind) -> Self {
-        self.inh_kind = inh_kind;
-        self
-    }
-
-    fn build(self) -> ty::GenericPredicates<'tcx> {
-        struct PredicatesCollector<'tcx> {
-            tcx: TyCtxt<'tcx>,
-            preds: Vec<(ty::Clause<'tcx>, Span)>,
-            args: ty::GenericArgsRef<'tcx>,
         }
 
-        impl<'tcx> PredicatesCollector<'tcx> {
+        fn with_own_preds(
-            fn new(tcx: TyCtxt<'tcx>, args: ty::GenericArgsRef<'tcx>) -> PredicatesCollector<'tcx> {
+            mut self,
-                PredicatesCollector { tcx, preds: vec![], args }
+            f: impl Fn(DefId) -> ty::GenericPredicates<'tcx>,
-            }
+            def_id: DefId,
-
+        ) -> Self {
-            fn with_own_preds(
+            let preds = f(def_id).instantiate_own(self.tcx, self.args);
-                mut self,
+            self.preds.extend(preds);
-                f: impl Fn(DefId) -> ty::GenericPredicates<'tcx>,
+            self
-                def_id: DefId,
-            ) -> Self {
-                let preds = f(def_id).instantiate_own(self.tcx, self.args);
-                self.preds.extend(preds);
-                self
-            }
-
-            fn with_preds(
-                mut self,
-                f: impl Fn(DefId) -> ty::GenericPredicates<'tcx> + Copy,
-                def_id: DefId,
-            ) -> Self {
-                let preds = f(def_id);
-                if let Some(parent_def_id) = preds.parent {
-                    self = self.with_own_preds(f, parent_def_id);
-                }
-                self.with_own_preds(f, def_id)
-            }
         }
-        let collector = PredicatesCollector::new(self.tcx, self.args);
 
-        // `explicit_predicates_of` is used here to avoid copying `Self: Trait` predicate.
+        fn with_preds(
-        // Note: `predicates_of` query can also add inferred outlives predicates, but that
+            mut self,
-        // is not the case here as `sig_id` is either a trait or a function.
+            f: impl Fn(DefId) -> ty::GenericPredicates<'tcx> + Copy,
-        let preds = match self.inh_kind {
+            def_id: DefId,
-            InheritanceKind::WithParent(false) => {
+        ) -> Self {
-                collector.with_preds(|def_id| self.tcx.explicit_predicates_of(def_id), self.sig_id)
+            let preds = f(def_id);
+            if let Some(parent_def_id) = preds.parent {
+                self = self.with_own_preds(f, parent_def_id);
             }
-            InheritanceKind::WithParent(true) => {
+            self.with_own_preds(f, def_id)
-                collector.with_preds(|def_id| self.tcx.predicates_of(def_id), self.sig_id)
-            }
-            InheritanceKind::Own => {
-                collector.with_own_preds(|def_id| self.tcx.predicates_of(def_id), self.sig_id)
-            }
-        }
-        .preds;
-
-        ty::GenericPredicates {
-            parent: self.parent,
-            predicates: self.tcx.arena.alloc_from_iter(preds),
         }
     }
+    let collector = PredicatesCollector::new(tcx, args);
+
+    // `explicit_predicates_of` is used here to avoid copying `Self: Trait` predicate.
+    // Note: `predicates_of` query can also add inferred outlives predicates, but that
+    // is not the case here as `sig_id` is either a trait or a function.
+    let preds = match inh_kind {
+        InheritanceKind::WithParent(false) => {
+            collector.with_preds(|def_id| tcx.explicit_predicates_of(def_id), sig_id)
+        }
+        InheritanceKind::WithParent(true) => {
+            collector.with_preds(|def_id| tcx.predicates_of(def_id), sig_id)
+        }
+        InheritanceKind::Own => {
+            collector.with_own_preds(|def_id| tcx.predicates_of(def_id), sig_id)
+        }
+    }
+    .preds;
+
+    ty::GenericPredicates { parent, predicates: tcx.arena.alloc_from_iter(preds) }
 }
 
-struct GenericArgsBuilder<'tcx> {
+fn build_generic_args<'tcx>(
     tcx: TyCtxt<'tcx>,
-    remap_table: RemapTable,
     sig_id: DefId,
     def_id: LocalDefId,
-}
+    args: ty::GenericArgsRef<'tcx>,
+) -> ty::GenericArgsRef<'tcx> {
+    let caller_generics = tcx.generics_of(def_id);
+    let callee_generics = tcx.generics_of(sig_id);
 
-impl<'tcx> GenericArgsBuilder<'tcx> {
+    let mut remap_table = FxHashMap::default();
-    fn new(tcx: TyCtxt<'tcx>, sig_id: DefId, def_id: LocalDefId) -> GenericArgsBuilder<'tcx> {
+    for caller_param in &caller_generics.own_params {
-        GenericArgsBuilder { tcx, remap_table: FxHashMap::default(), sig_id, def_id }
+        let callee_index = callee_generics.param_def_id_to_index(tcx, caller_param.def_id).unwrap();
+        remap_table.insert(callee_index, caller_param.index);
     }
 
-    fn build_from_args(mut self, args: ty::GenericArgsRef<'tcx>) -> ty::GenericArgsRef<'tcx> {
+    let mut folder = ParamIndexRemapper { tcx, remap_table };
-        let caller_generics = self.tcx.generics_of(self.def_id);
+    args.fold_with(&mut folder)
-        let callee_generics = self.tcx.generics_of(self.sig_id);
-
-        for caller_param in &caller_generics.own_params {
-            let callee_index =
-                callee_generics.param_def_id_to_index(self.tcx, caller_param.def_id).unwrap();
-            self.remap_table.insert(callee_index, caller_param.index);
-        }
-
-        let mut folder = ParamIndexRemapper { tcx: self.tcx, remap_table: self.remap_table };
-        args.fold_with(&mut folder)
-    }
 }
 
 fn create_generic_args<'tcx>(
@@ -314,8 +257,6 @@ fn create_generic_args<'tcx>(
     def_id: LocalDefId,
     sig_id: DefId,
 ) -> ty::GenericArgsRef<'tcx> {
-    let builder = GenericArgsBuilder::new(tcx, sig_id, def_id);
-
     let caller_kind = fn_kind(tcx, def_id.into());
     let callee_kind = fn_kind(tcx, sig_id);
     match (caller_kind, callee_kind) {
@@ -325,7 +266,7 @@ fn create_generic_args<'tcx>(
         | (FnKind::AssocTrait, FnKind::Free)
         | (FnKind::AssocTrait, FnKind::AssocTrait) => {
             let args = ty::GenericArgs::identity_for_item(tcx, sig_id);
-            builder.build_from_args(args)
+            build_generic_args(tcx, sig_id, def_id, args)
         }
 
         (FnKind::AssocTraitImpl, FnKind::AssocTrait) => {
@@ -335,8 +276,9 @@ fn create_generic_args<'tcx>(
                 tcx.impl_trait_header(parent).unwrap().trait_ref.instantiate_identity().args;
 
             let trait_args = ty::GenericArgs::identity_for_item(tcx, sig_id);
-            let method_args = tcx.mk_args_from_iter(trait_args.iter().skip(callee_generics.parent_count));
+            let method_args =
-            let method_args = builder.build_from_args(method_args);
+                tcx.mk_args_from_iter(trait_args.iter().skip(callee_generics.parent_count));
+            let method_args = build_generic_args(tcx, sig_id, def_id, method_args);
 
             tcx.mk_args_from_iter(parent_args.iter().chain(method_args))
         }
@@ -347,16 +289,16 @@ fn create_generic_args<'tcx>(
             let generic_self_ty = ty::GenericArg::from(self_ty);
 
             let trait_args = ty::GenericArgs::identity_for_item(tcx, sig_id);
-            let trait_args = builder.build_from_args(trait_args);
+            let trait_args = build_generic_args(tcx, sig_id, def_id, trait_args);
 
             let args = std::iter::once(generic_self_ty).chain(trait_args.iter().skip(1));
             tcx.mk_args_from_iter(args)
         }
 
         // For trait impl's `sig_id` is always equal to the corresponding trait method.
+        // For inherent methods delegation is not yet supported.
         (FnKind::AssocTraitImpl, _)
         | (_, FnKind::AssocTraitImpl)
-        // Delegation to inherent methods is not yet supported.
         | (_, FnKind::AssocInherentImpl) => unreachable!(),
     }
 }
@@ -377,39 +319,31 @@ pub(crate) fn inherit_generics_for_delegation_item<'tcx>(
     def_id: LocalDefId,
     sig_id: DefId,
 ) -> ty::Generics {
-    let builder = GenericsBuilder::new(tcx, sig_id);
-
     let caller_kind = fn_kind(tcx, def_id.into());
     let callee_kind = fn_kind(tcx, sig_id);
     match (caller_kind, callee_kind) {
-        (FnKind::Free, FnKind::Free)
+        (FnKind::Free, FnKind::Free) | (FnKind::Free, FnKind::AssocTrait) => {
-        | (FnKind::Free, FnKind::AssocTrait) => builder.with_inheritance_kind(InheritanceKind::WithParent(true)).build(),
+            build_generics(tcx, sig_id, None, InheritanceKind::WithParent(true))
+        }
 
         (FnKind::AssocTraitImpl, FnKind::AssocTrait) => {
-            builder
+            build_generics(tcx, sig_id, Some(tcx.parent(def_id.into())), InheritanceKind::Own)
-            .with_parent(tcx.parent(def_id.into()))
-            .with_inheritance_kind(InheritanceKind::Own)
-            .build()
         }
 
         (FnKind::AssocInherentImpl, FnKind::AssocTrait)
-        | (FnKind::AssocTrait, FnKind::AssocTrait) => {
+        | (FnKind::AssocTrait, FnKind::AssocTrait)
-            builder
+        | (FnKind::AssocInherentImpl, FnKind::Free)
-            .with_parent(tcx.parent(def_id.into()))
+        | (FnKind::AssocTrait, FnKind::Free) => build_generics(
-            .build()
+            tcx,
-        }
+            sig_id,
-
+            Some(tcx.parent(def_id.into())),
-        (FnKind::AssocInherentImpl, FnKind::Free)
+            InheritanceKind::WithParent(false),
-        | (FnKind::AssocTrait, FnKind::Free) => {
+        ),
-            builder
-            .with_parent(tcx.parent(def_id.into()))
-            .build()
-        }
 
         // For trait impl's `sig_id` is always equal to the corresponding trait method.
+        // For inherent methods delegation is not yet supported.
         (FnKind::AssocTraitImpl, _)
         | (_, FnKind::AssocTraitImpl)
-        // Delegation to inherent methods is not yet supported.
         | (_, FnKind::AssocInherentImpl) => unreachable!(),
     }
 }
@@ -420,36 +354,36 @@ pub(crate) fn inherit_predicates_for_delegation_item<'tcx>(
     sig_id: DefId,
 ) -> ty::GenericPredicates<'tcx> {
     let args = create_generic_args(tcx, def_id, sig_id);
-    let builder = PredicatesBuilder::new(tcx, args, sig_id);
-
     let caller_kind = fn_kind(tcx, def_id.into());
     let callee_kind = fn_kind(tcx, sig_id);
     match (caller_kind, callee_kind) {
-        (FnKind::Free, FnKind::Free)
+        (FnKind::Free, FnKind::Free) | (FnKind::Free, FnKind::AssocTrait) => {
-        | (FnKind::Free, FnKind::AssocTrait) => {
+            build_predicates(tcx, sig_id, None, InheritanceKind::WithParent(true), args)
-            builder.with_inheritance_kind(InheritanceKind::WithParent(true)).build()
         }
 
-        (FnKind::AssocTraitImpl, FnKind::AssocTrait) => {
+        (FnKind::AssocTraitImpl, FnKind::AssocTrait) => build_predicates(
-            builder
+            tcx,
-            .with_parent(tcx.parent(def_id.into()))
+            sig_id,
-            .with_inheritance_kind(InheritanceKind::Own)
+            Some(tcx.parent(def_id.into())),
-            .build()
+            InheritanceKind::Own,
-        }
+            args,
+        ),
 
         (FnKind::AssocInherentImpl, FnKind::AssocTrait)
         | (FnKind::AssocTrait, FnKind::AssocTrait)
         | (FnKind::AssocInherentImpl, FnKind::Free)
-        | (FnKind::AssocTrait, FnKind::Free) => {
+        | (FnKind::AssocTrait, FnKind::Free) => build_predicates(
-            builder
+            tcx,
-                .with_parent(tcx.parent(def_id.into()))
+            sig_id,
-                .build()
+            Some(tcx.parent(def_id.into())),
-        }
+            InheritanceKind::WithParent(false),
+            args,
+        ),
 
         // For trait impl's `sig_id` is always equal to the corresponding trait method.
+        // For inherent methods delegation is not yet supported.
         (FnKind::AssocTraitImpl, _)
         | (_, FnKind::AssocTraitImpl)
-        // Delegation to inherent methods is not yet supported.
         | (_, FnKind::AssocInherentImpl) => unreachable!(),
     }
 }

compiler/rustc_hir_analysis/src/errors/wrong_number_of_generic_args.rs

@@ -495,6 +495,7 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
                         .iter()
                         .any(|constraint| constraint.ident.name == item.name)
                 })
+                .filter(|item| !item.is_impl_trait_in_trait())
                 .map(|item| self.tcx.item_ident(item.def_id).to_string())
                 .collect()
         } else {

compiler/rustc_hir_analysis/src/hir_ty_lowering/generics.rs

@@ -273,7 +273,7 @@ pub fn lower_generic_args<'tcx: 'a, 'a>(
 
                             // We lower to an infer even when the feature gate is not enabled
                             // as it is useful for diagnostics to be able to see a `ConstKind::Infer`
-                            args.push(ctx.provided_kind(&args, param, arg));
+                            args.push(ctx.provided_kind(param, arg));
                             args_iter.next();
                             params.next();
                         }

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -296,7 +296,6 @@ pub trait GenericArgsLowerer<'a, 'tcx> {
 
     fn provided_kind(
         &mut self,
-        preceding_args: &[ty::GenericArg<'tcx>],
         param: &ty::GenericParamDef,
         arg: &GenericArg<'tcx>,
     ) -> ty::GenericArg<'tcx>;
@@ -480,7 +479,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
             fn provided_kind(
                 &mut self,
-                _preceding_args: &[ty::GenericArg<'tcx>],
                 param: &ty::GenericParamDef,
                 arg: &GenericArg<'tcx>,
             ) -> ty::GenericArg<'tcx> {

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -34,7 +34,7 @@
 //! impl<T, I: Iterator<Item=T>> SpecExtend<T> for I { /* default impl */ }
 //! ```
 //!
-//! We get that the generic pamameters for `impl2` are `[T, std::vec::IntoIter<T>]`.
+//! We get that the generic parameters for `impl2` are `[T, std::vec::IntoIter<T>]`.
 //! `T` is constrained to be `<I as Iterator>::Item`, so we check only
 //! `std::vec::IntoIter<T>` for repeated parameters, which it doesn't have. The
 //! predicates of `impl1` are only `T: Sized`, which is also a predicate of
@@ -119,7 +119,6 @@ fn check_always_applicable(
     impl2_node: Node,
 ) -> Result<(), ErrorGuaranteed> {
     let span = tcx.def_span(impl1_def_id);
-    let mut res = check_has_items(tcx, impl1_def_id, impl2_node, span);
 
     let (impl1_args, impl2_args) = get_impl_args(tcx, impl1_def_id, impl2_node)?;
     let impl2_def_id = impl2_node.def_id();
@@ -131,11 +130,10 @@ fn check_always_applicable(
         unconstrained_parent_impl_args(tcx, impl2_def_id, impl2_args)
     };
 
-    res = res.and(check_static_lifetimes(tcx, &parent_args, span));
+    check_has_items(tcx, impl1_def_id, impl2_node, span)
-    res = res.and(check_duplicate_params(tcx, impl1_args, parent_args, span));
+        .and(check_static_lifetimes(tcx, &parent_args, span))
-    res = res.and(check_predicates(tcx, impl1_def_id, impl1_args, impl2_node, impl2_args, span));
+        .and(check_duplicate_params(tcx, impl1_args, parent_args, span))
-
+        .and(check_predicates(tcx, impl1_def_id, impl1_args, impl2_node, impl2_args, span))
-    res
 }
 
 fn check_has_items(

compiler/rustc_hir_analysis/src/lib.rs

@@ -83,12 +83,11 @@ pub mod autoderef;
 mod bounds;
 mod check_unused;
 mod coherence;
-mod delegation;
+mod collect;
-pub mod hir_ty_lowering;
-// FIXME: This module shouldn't be public.
-pub mod collect;
 mod constrained_generic_params;
+mod delegation;
 mod errors;
+pub mod hir_ty_lowering;
 pub mod hir_wf_check;
 mod impl_wf_check;
 mod outlives;
@@ -104,7 +103,8 @@ use rustc_middle::ty::{self, Const, Ty, TyCtxt};
 use rustc_span::Span;
 use rustc_trait_selection::traits;
 
-use self::hir_ty_lowering::{FeedConstTy, HirTyLowerer};
+pub use crate::collect::suggest_impl_trait;
+use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer};
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 

compiler/rustc_hir_analysis/src/outlives/implicit_infer.rs

@@ -24,7 +24,7 @@ pub(super) fn infer_predicates(
 
     // If new predicates were added then we need to re-calculate
     // all crates since there could be new implied predicates.
-    'outer: loop {
+    loop {
         let mut predicates_added = false;
 
         // Visit all the crates and infer predicates
@@ -90,7 +90,7 @@ pub(super) fn infer_predicates(
         }
 
         if !predicates_added {
-            break 'outer;
+            break;
         }
     }
 

compiler/rustc_hir_analysis/src/variance/mod.rs

@@ -27,9 +27,6 @@ mod solve;
 
 pub(crate) mod dump;
 
-/// Code for transforming variances.
-mod xform;
-
 pub(crate) fn provide(providers: &mut Providers) {
     *providers = Providers { variances_of, crate_variances, ..*providers };
 }

compiler/rustc_hir_analysis/src/variance/solve.rs

@@ -12,8 +12,26 @@ use tracing::debug;
 use super::constraints::*;
 use super::terms::VarianceTerm::*;
 use super::terms::*;
-use super::xform::*;
 
+fn glb(v1: ty::Variance, v2: ty::Variance) -> ty::Variance {
+    // Greatest lower bound of the variance lattice as defined in The Paper:
+    //
+    //       *
+    //    -     +
+    //       o
+    match (v1, v2) {
+        (ty::Invariant, _) | (_, ty::Invariant) => ty::Invariant,
+
+        (ty::Covariant, ty::Contravariant) => ty::Invariant,
+        (ty::Contravariant, ty::Covariant) => ty::Invariant,
+
+        (ty::Covariant, ty::Covariant) => ty::Covariant,
+
+        (ty::Contravariant, ty::Contravariant) => ty::Contravariant,
+
+        (x, ty::Bivariant) | (ty::Bivariant, x) => x,
+    }
+}
 struct SolveContext<'a, 'tcx> {
     terms_cx: TermsContext<'a, 'tcx>,
     constraints: Vec<Constraint<'a>>,

compiler/rustc_hir_analysis/src/variance/xform.rs

@@ -1,22 +0,0 @@
-use rustc_middle::ty;
-
-pub(crate) fn glb(v1: ty::Variance, v2: ty::Variance) -> ty::Variance {
-    // Greatest lower bound of the variance lattice as
-    // defined in The Paper:
-    //
-    //       *
-    //    -     +
-    //       o
-    match (v1, v2) {
-        (ty::Invariant, _) | (_, ty::Invariant) => ty::Invariant,
-
-        (ty::Covariant, ty::Contravariant) => ty::Invariant,
-        (ty::Contravariant, ty::Covariant) => ty::Invariant,
-
-        (ty::Covariant, ty::Covariant) => ty::Covariant,
-
-        (ty::Contravariant, ty::Contravariant) => ty::Contravariant,
-
-        (x, ty::Bivariant) | (ty::Bivariant, x) => x,
-    }
-}

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1261,7 +1261,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
             fn provided_kind(
                 &mut self,
-                _preceding_args: &[ty::GenericArg<'tcx>],
                 param: &ty::GenericParamDef,
                 arg: &GenericArg<'tcx>,
             ) -> ty::GenericArg<'tcx> {

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -1147,6 +1147,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 Some(self.param_env.and(trace.values)),
                                 e,
                                 true,
+                                None,
                             );
                         }
                     }

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -31,12 +31,12 @@ use crate::{CoroutineTypes, Diverges, EnclosingBreakables, TypeckRootCtxt};
 /// functions, closures, and `const`s, including performing type inference
 /// with [`InferCtxt`].
 ///
-/// This is in contrast to [`ItemCtxt`], which is used to type-check item *signatures*
+/// This is in contrast to `rustc_hir_analysis::collect::ItemCtxt`, which is
-/// and thus does not perform type inference.
+/// used to type-check item *signatures* and thus does not perform type
+/// inference.
 ///
-/// See [`ItemCtxt`]'s docs for more.
+/// See `ItemCtxt`'s docs for more.
 ///
-/// [`ItemCtxt`]: rustc_hir_analysis::collect::ItemCtxt
 /// [`InferCtxt`]: infer::InferCtxt
 pub(crate) struct FnCtxt<'a, 'tcx> {
     pub(super) body_id: LocalDefId,

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -12,8 +12,8 @@ use rustc_hir::{
     GenericBound, HirId, Node, PatExpr, PatExprKind, Path, QPath, Stmt, StmtKind, TyKind,
     WherePredicateKind, expr_needs_parens,
 };
-use rustc_hir_analysis::collect::suggest_impl_trait;
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
+use rustc_hir_analysis::suggest_impl_trait;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::span_bug;

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -413,7 +413,6 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
 
             fn provided_kind(
                 &mut self,
-                _preceding_args: &[ty::GenericArg<'tcx>],
                 param: &ty::GenericParamDef,
                 arg: &GenericArg<'tcx>,
             ) -> ty::GenericArg<'tcx> {

compiler/rustc_interface/src/tests.rs

@@ -8,12 +8,12 @@ use rustc_data_structures::profiling::TimePassesFormat;
 use rustc_errors::emitter::HumanReadableErrorType;
 use rustc_errors::{ColorConfig, registry};
 use rustc_session::config::{
-    BranchProtection, CFGuard, Cfg, CollapseMacroDebuginfo, CoverageLevel, CoverageOptions,
+    AutoDiff, BranchProtection, CFGuard, Cfg, CollapseMacroDebuginfo, CoverageLevel,
-    DebugInfo, DumpMonoStatsFormat, ErrorOutputType, ExternEntry, ExternLocation, Externs,
+    CoverageOptions, DebugInfo, DumpMonoStatsFormat, ErrorOutputType, ExternEntry, ExternLocation,
-    FmtDebug, FunctionReturn, InliningThreshold, Input, InstrumentCoverage, InstrumentXRay,
+    Externs, FmtDebug, FunctionReturn, InliningThreshold, Input, InstrumentCoverage,
-    LinkSelfContained, LinkerPluginLto, LocationDetail, LtoCli, MirIncludeSpans, NextSolverConfig,
+    InstrumentXRay, LinkSelfContained, LinkerPluginLto, LocationDetail, LtoCli, MirIncludeSpans,
-    OomStrategy, Options, OutFileName, OutputType, OutputTypes, PAuthKey, PacRet, Passes,
+    NextSolverConfig, OomStrategy, Options, OutFileName, OutputType, OutputTypes, PAuthKey, PacRet,
-    PatchableFunctionEntry, Polonius, ProcMacroExecutionStrategy, Strip, SwitchWithOptPath,
+    Passes, PatchableFunctionEntry, Polonius, ProcMacroExecutionStrategy, Strip, SwitchWithOptPath,
     SymbolManglingVersion, WasiExecModel, build_configuration, build_session_options,
     rustc_optgroups,
 };
@@ -760,6 +760,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(allow_features, Some(vec![String::from("lang_items")]));
     tracked!(always_encode_mir, true);
     tracked!(assume_incomplete_release, true);
+    tracked!(autodiff, vec![AutoDiff::Print]);
     tracked!(binary_dep_depinfo, true);
     tracked!(box_noalias, false);
     tracked!(

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -965,7 +965,8 @@ extern "C" LLVMValueRef LLVMRustGetLastInstruction(LLVMBasicBlockRef BB) {
   return nullptr;
 }
 
-extern "C" void LLVMRustEraseInstBefore(LLVMBasicBlockRef bb, LLVMValueRef I) {
+extern "C" void LLVMRustEraseInstUntilInclusive(LLVMBasicBlockRef bb,
+                                                LLVMValueRef I) {
   auto &BB = *unwrap(bb);
   auto &Inst = *unwrap<Instruction>(I);
   auto It = BB.begin();
@@ -973,8 +974,6 @@ extern "C" void LLVMRustEraseInstBefore(LLVMBasicBlockRef bb, LLVMValueRef I) {
     ++It;
   // Make sure we found the Instruction.
   assert(It != BB.end());
-  // We don't want to erase the instruction itself.
-  It--;
   // Delete in rev order to ensure no dangling references.
   while (It != BB.begin()) {
     auto Prev = std::prev(It);

compiler/rustc_middle/messages.ftl

@@ -32,6 +32,8 @@ middle_assert_shl_overflow =
 middle_assert_shr_overflow =
     attempt to shift right by `{$val}`, which would overflow
 
+middle_autodiff_unsafe_inner_const_ref = reading from a `Duplicated` const {$ty} is unsafe
+
 middle_bounds_check =
     index out of bounds: the length is {$len} but the index is {$index}
 
@@ -107,6 +109,8 @@ middle_type_length_limit = reached the type-length limit while instantiating `{$
 middle_unknown_layout =
     the type `{$ty}` has an unknown layout
 
+middle_unsupported_union = we don't support unions yet: '{$ty_name}'
+
 middle_values_too_big =
     values of the type `{$ty}` are too big for the target architecture
 

compiler/rustc_middle/src/arena.rs

@@ -87,6 +87,7 @@ macro_rules! arena_types {
             [] codegen_unit: rustc_middle::mir::mono::CodegenUnit<'tcx>,
             [decode] attribute: rustc_hir::Attribute,
             [] name_set: rustc_data_structures::unord::UnordSet<rustc_span::Symbol>,
+            [] autodiff_item: rustc_ast::expand::autodiff_attrs::AutoDiffItem,
             [] ordered_name_set: rustc_data_structures::fx::FxIndexSet<rustc_span::Symbol>,
             [] pats: rustc_middle::ty::PatternKind<'tcx>,
 

compiler/rustc_middle/src/error.rs

@@ -37,6 +37,20 @@ pub struct OpaqueHiddenTypeMismatch<'tcx> {
     pub sub: TypeMismatchReason,
 }
 
+#[derive(Diagnostic)]
+#[diag(middle_unsupported_union)]
+pub struct UnsupportedUnion {
+    pub ty_name: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(middle_autodiff_unsafe_inner_const_ref)]
+pub struct AutodiffUnsafeInnerConstRef {
+    #[primary_span]
+    pub span: Span,
+    pub ty: String,
+}
+
 #[derive(Subdiagnostic)]
 pub enum TypeMismatchReason {
     #[label(middle_conflict_types)]

compiler/rustc_middle/src/middle/codegen_fn_attrs.rs

@@ -1,4 +1,5 @@
 use rustc_abi::Align;
+use rustc_ast::expand::autodiff_attrs::AutoDiffAttrs;
 use rustc_attr_parsing::{InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_span::Symbol;
@@ -52,6 +53,8 @@ pub struct CodegenFnAttrs {
     /// The `#[patchable_function_entry(...)]` attribute. Indicates how many nops should be around
     /// the function entry.
     pub patchable_function_entry: Option<PatchableFunctionEntry>,
+    /// For the `#[autodiff]` macros.
+    pub autodiff_item: Option<AutoDiffAttrs>,
 }
 
 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
@@ -160,6 +163,7 @@ impl CodegenFnAttrs {
             instruction_set: None,
             alignment: None,
             patchable_function_entry: None,
+            autodiff_item: None,
         }
     }
 

compiler/rustc_middle/src/mir/mono.rs

@@ -1,6 +1,7 @@
 use std::fmt;
 use std::hash::Hash;
 
+use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_attr_parsing::InlineAttr;
 use rustc_data_structures::base_n::{BaseNString, CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -246,6 +247,7 @@ impl ToStableHashKey<StableHashingContext<'_>> for MonoItem<'_> {
 pub struct MonoItemPartitions<'tcx> {
     pub codegen_units: &'tcx [CodegenUnit<'tcx>],
     pub all_mono_items: &'tcx DefIdSet,
+    pub autodiff_items: &'tcx [AutoDiffItem],
 }
 
 #[derive(Debug, HashStable)]

compiler/rustc_monomorphize/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 rustc_abi = { path = "../rustc_abi" }
+rustc_ast = { path = "../rustc_ast" }
 rustc_attr_parsing = { path = "../rustc_attr_parsing" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
@@ -15,6 +16,7 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
+rustc_symbol_mangling = { path = "../rustc_symbol_mangling" }
 rustc_target = { path = "../rustc_target" }
 serde = "1"
 serde_json = "1"

compiler/rustc_monomorphize/src/collector.rs

@@ -257,7 +257,7 @@ struct SharedState<'tcx> {
 
 pub(crate) struct UsageMap<'tcx> {
     // Maps every mono item to the mono items used by it.
-    used_map: UnordMap<MonoItem<'tcx>, Vec<MonoItem<'tcx>>>,
+    pub used_map: UnordMap<MonoItem<'tcx>, Vec<MonoItem<'tcx>>>,
 
     // Maps every mono item to the mono items that use it.
     user_map: UnordMap<MonoItem<'tcx>, Vec<MonoItem<'tcx>>>,

compiler/rustc_monomorphize/src/partitioning.rs

@@ -92,6 +92,8 @@
 //! source-level module, functions from the same module will be available for
 //! inlining, even when they are not marked `#[inline]`.
 
+mod autodiff;
+
 use std::cmp;
 use std::collections::hash_map::Entry;
 use std::fs::{self, File};
@@ -251,7 +253,17 @@ where
             can_export_generics,
             always_export_generics,
         );
-        if visibility == Visibility::Hidden && can_be_internalized {
+
+        // We can't differentiate something that got inlined.
+        let autodiff_active = cfg!(llvm_enzyme)
+            && cx
+                .tcx
+                .codegen_fn_attrs(mono_item.def_id())
+                .autodiff_item
+                .as_ref()
+                .is_some_and(|ad| ad.is_active());
+
+        if !autodiff_active && visibility == Visibility::Hidden && can_be_internalized {
             internalization_candidates.insert(mono_item);
         }
         let size_estimate = mono_item.size_estimate(cx.tcx);
@@ -1176,6 +1188,18 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         })
         .collect();
 
+    let autodiff_mono_items: Vec<_> = items
+        .iter()
+        .filter_map(|item| match *item {
+            MonoItem::Fn(ref instance) => Some((item, instance)),
+            _ => None,
+        })
+        .collect();
+
+    let autodiff_items =
+        autodiff::find_autodiff_source_functions(tcx, &usage_map, autodiff_mono_items);
+    let autodiff_items = tcx.arena.alloc_from_iter(autodiff_items);
+
     // Output monomorphization stats per def_id
     if let SwitchWithOptPath::Enabled(ref path) = tcx.sess.opts.unstable_opts.dump_mono_stats {
         if let Err(err) =
@@ -1236,7 +1260,11 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         }
     }
 
-    MonoItemPartitions { all_mono_items: tcx.arena.alloc(mono_items), codegen_units }
+    MonoItemPartitions {
+        all_mono_items: tcx.arena.alloc(mono_items),
+        codegen_units,
+        autodiff_items,
+    }
 }
 
 /// Outputs stats about instantiation counts and estimated size, per `MonoItem`'s

compiler/rustc_monomorphize/src/partitioning/autodiff.rs

@@ -0,0 +1,121 @@
+use rustc_ast::expand::autodiff_attrs::{AutoDiffItem, DiffActivity};
+use rustc_hir::def_id::LOCAL_CRATE;
+use rustc_middle::bug;
+use rustc_middle::mir::mono::MonoItem;
+use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
+use rustc_symbol_mangling::symbol_name_for_instance_in_crate;
+use tracing::{debug, trace};
+
+use crate::partitioning::UsageMap;
+
+fn adjust_activity_to_abi<'tcx>(tcx: TyCtxt<'tcx>, fn_ty: Ty<'tcx>, da: &mut Vec<DiffActivity>) {
+    if !matches!(fn_ty.kind(), ty::FnDef(..)) {
+        bug!("expected fn def for autodiff, got {:?}", fn_ty);
+    }
+    let fnc_binder: ty::Binder<'_, ty::FnSig<'_>> = fn_ty.fn_sig(tcx);
+
+    // If rustc compiles the unmodified primal, we know that this copy of the function
+    // also has correct lifetimes. We know that Enzyme won't free the shadow too early
+    // (or actually at all), so let's strip lifetimes when computing the layout.
+    let x = tcx.instantiate_bound_regions_with_erased(fnc_binder);
+    let mut new_activities = vec![];
+    let mut new_positions = vec![];
+    for (i, ty) in x.inputs().iter().enumerate() {
+        if let Some(inner_ty) = ty.builtin_deref(true) {
+            if ty.is_fn_ptr() {
+                // FIXME(ZuseZ4): add a nicer error, or just figure out how to support them,
+                // since Enzyme itself can handle them.
+                tcx.dcx().err("function pointers are currently not supported in autodiff");
+            }
+            if inner_ty.is_slice() {
+                // We know that the length will be passed as extra arg.
+                if !da.is_empty() {
+                    // We are looking at a slice. The length of that slice will become an
+                    // extra integer on llvm level. Integers are always const.
+                    // However, if the slice get's duplicated, we want to know to later check the
+                    // size. So we mark the new size argument as FakeActivitySize.
+                    let activity = match da[i] {
+                        DiffActivity::DualOnly
+                        | DiffActivity::Dual
+                        | DiffActivity::DuplicatedOnly
+                        | DiffActivity::Duplicated => DiffActivity::FakeActivitySize,
+                        DiffActivity::Const => DiffActivity::Const,
+                        _ => bug!("unexpected activity for ptr/ref"),
+                    };
+                    new_activities.push(activity);
+                    new_positions.push(i + 1);
+                }
+                continue;
+            }
+        }
+    }
+    // now add the extra activities coming from slices
+    // Reverse order to not invalidate the indices
+    for _ in 0..new_activities.len() {
+        let pos = new_positions.pop().unwrap();
+        let activity = new_activities.pop().unwrap();
+        da.insert(pos, activity);
+    }
+}
+
+pub(crate) fn find_autodiff_source_functions<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    usage_map: &UsageMap<'tcx>,
+    autodiff_mono_items: Vec<(&MonoItem<'tcx>, &Instance<'tcx>)>,
+) -> Vec<AutoDiffItem> {
+    let mut autodiff_items: Vec<AutoDiffItem> = vec![];
+    for (item, instance) in autodiff_mono_items {
+        let target_id = instance.def_id();
+        let cg_fn_attr = tcx.codegen_fn_attrs(target_id).autodiff_item.clone();
+        let Some(target_attrs) = cg_fn_attr else {
+            continue;
+        };
+        let mut input_activities: Vec<DiffActivity> = target_attrs.input_activity.clone();
+        if target_attrs.is_source() {
+            trace!("source found: {:?}", target_id);
+        }
+        if !target_attrs.apply_autodiff() {
+            continue;
+        }
+
+        let target_symbol = symbol_name_for_instance_in_crate(tcx, instance.clone(), LOCAL_CRATE);
+
+        let source =
+            usage_map.used_map.get(&item).unwrap().into_iter().find_map(|item| match *item {
+                MonoItem::Fn(ref instance_s) => {
+                    let source_id = instance_s.def_id();
+                    if let Some(ad) = &tcx.codegen_fn_attrs(source_id).autodiff_item
+                        && ad.is_active()
+                    {
+                        return Some(instance_s);
+                    }
+                    None
+                }
+                _ => None,
+            });
+        let inst = match source {
+            Some(source) => source,
+            None => continue,
+        };
+
+        debug!("source_id: {:?}", inst.def_id());
+        let fn_ty = inst.ty(tcx, ty::TypingEnv::fully_monomorphized());
+        assert!(fn_ty.is_fn());
+        adjust_activity_to_abi(tcx, fn_ty, &mut input_activities);
+        let symb = symbol_name_for_instance_in_crate(tcx, inst.clone(), LOCAL_CRATE);
+
+        let mut new_target_attrs = target_attrs.clone();
+        new_target_attrs.input_activity = input_activities;
+        let itm = new_target_attrs.into_item(symb, target_symbol);
+        autodiff_items.push(itm);
+    }
+
+    if !autodiff_items.is_empty() {
+        trace!("AUTODIFF ITEMS EXIST");
+        for item in &mut *autodiff_items {
+            trace!("{}", &item);
+        }
+    }
+
+    autodiff_items
+}

compiler/rustc_passes/src/check_attr.rs

@@ -2471,6 +2471,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 }))),
                 terr,
                 false,
+                None,
             );
             diag.emit();
             self.abort.set(true);

compiler/rustc_session/src/config.rs

@@ -189,6 +189,39 @@ pub enum CoverageLevel {
     Mcdc,
 }
 
+/// The different settings that the `-Z autodiff` flag can have.
+#[derive(Clone, Copy, PartialEq, Hash, Debug)]
+pub enum AutoDiff {
+    /// Print TypeAnalysis information
+    PrintTA,
+    /// Print ActivityAnalysis Information
+    PrintAA,
+    /// Print Performance Warnings from Enzyme
+    PrintPerf,
+    /// Combines the three print flags above.
+    Print,
+    /// Print the whole module, before running opts.
+    PrintModBefore,
+    /// Print the whole module just before we pass it to Enzyme.
+    /// For Debug purpose, prefer the OPT flag below
+    PrintModAfterOpts,
+    /// Print the module after Enzyme differentiated everything.
+    PrintModAfterEnzyme,
+
+    /// Enzyme's loose type debug helper (can cause incorrect gradients)
+    LooseTypes,
+
+    /// More flags
+    NoModOptAfter,
+    /// Tell Enzyme to run LLVM Opts on each function it generated. By default off,
+    /// since we already optimize the whole module after Enzyme is done.
+    EnableFncOpt,
+    NoVecUnroll,
+    RuntimeActivity,
+    /// Runs Enzyme specific Inlining
+    Inline,
+}
+
 /// Settings for `-Z instrument-xray` flag.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
 pub struct InstrumentXRay {
@@ -2902,7 +2935,7 @@ pub(crate) mod dep_tracking {
     };
 
     use super::{
-        BranchProtection, CFGuard, CFProtection, CollapseMacroDebuginfo, CoverageOptions,
+        AutoDiff, BranchProtection, CFGuard, CFProtection, CollapseMacroDebuginfo, CoverageOptions,
         CrateType, DebugInfo, DebugInfoCompression, ErrorOutputType, FmtDebug, FunctionReturn,
         InliningThreshold, InstrumentCoverage, InstrumentXRay, LinkerPluginLto, LocationDetail,
         LtoCli, MirStripDebugInfo, NextSolverConfig, OomStrategy, OptLevel, OutFileName,
@@ -2950,6 +2983,7 @@ pub(crate) mod dep_tracking {
     }
 
     impl_dep_tracking_hash_via_hash!(
+        AutoDiff,
         bool,
         usize,
         NonZero<usize>,

compiler/rustc_session/src/options.rs

@@ -398,6 +398,7 @@ mod desc {
     pub(crate) const parse_list: &str = "a space-separated list of strings";
     pub(crate) const parse_list_with_polarity: &str =
         "a comma-separated list of strings, with elements beginning with + or -";
+    pub(crate) const parse_autodiff: &str = "a comma separated list of settings: `Print`, `PrintTA`, `PrintAA`, `PrintPerf`, `PrintModBefore`, `PrintModAfterOpts`, `PrintModAfterEnzyme`, `LooseTypes`, `NoModOptAfter`, `EnableFncOpt`, `NoVecUnroll`, `Inline`";
     pub(crate) const parse_comma_list: &str = "a comma-separated list of strings";
     pub(crate) const parse_opt_comma_list: &str = parse_comma_list;
     pub(crate) const parse_number: &str = "a number";
@@ -1029,6 +1030,38 @@ pub mod parse {
         }
     }
 
+    pub(crate) fn parse_autodiff(slot: &mut Vec<AutoDiff>, v: Option<&str>) -> bool {
+        let Some(v) = v else {
+            *slot = vec![];
+            return true;
+        };
+        let mut v: Vec<&str> = v.split(",").collect();
+        v.sort_unstable();
+        for &val in v.iter() {
+            let variant = match val {
+                "PrintTA" => AutoDiff::PrintTA,
+                "PrintAA" => AutoDiff::PrintAA,
+                "PrintPerf" => AutoDiff::PrintPerf,
+                "Print" => AutoDiff::Print,
+                "PrintModBefore" => AutoDiff::PrintModBefore,
+                "PrintModAfterOpts" => AutoDiff::PrintModAfterOpts,
+                "PrintModAfterEnzyme" => AutoDiff::PrintModAfterEnzyme,
+                "LooseTypes" => AutoDiff::LooseTypes,
+                "NoModOptAfter" => AutoDiff::NoModOptAfter,
+                "EnableFncOpt" => AutoDiff::EnableFncOpt,
+                "NoVecUnroll" => AutoDiff::NoVecUnroll,
+                "Inline" => AutoDiff::Inline,
+                _ => {
+                    // FIXME(ZuseZ4): print an error saying which value is not recognized
+                    return false;
+                }
+            };
+            slot.push(variant);
+        }
+
+        true
+    }
+
     pub(crate) fn parse_instrument_coverage(
         slot: &mut InstrumentCoverage,
         v: Option<&str>,
@@ -1736,6 +1769,22 @@ options! {
          either `loaded` or `not-loaded`."),
     assume_incomplete_release: bool = (false, parse_bool, [TRACKED],
         "make cfg(version) treat the current version as incomplete (default: no)"),
+    autodiff: Vec<crate::config::AutoDiff> = (Vec::new(), parse_autodiff, [TRACKED],
+        "a list of optional autodiff flags to enable
+         Optional extra settings:
+         `=PrintTA`
+         `=PrintAA`
+         `=PrintPerf`
+         `=Print`
+         `=PrintModBefore`
+         `=PrintModAfterOpts`
+         `=PrintModAfterEnzyme`
+         `=LooseTypes`
+         `=NoModOptAfter`
+         `=EnableFncOpt`
+         `=NoVecUnroll`
+         `=Inline`
+         Multiple options can be combined with commas."),
     #[rustc_lint_opt_deny_field_access("use `Session::binary_dep_depinfo` instead of this field")]
     binary_dep_depinfo: bool = (false, parse_bool, [TRACKED],
         "include artifacts (sysroot, crate dependencies) used during compilation in dep-info \

compiler/rustc_span/src/symbol.rs

@@ -502,7 +502,6 @@ symbols! {
         augmented_assignments,
         auto_traits,
         autodiff,
-        autodiff_fallback,
         automatically_derived,
         avx,
         avx512_target_feature,
@@ -568,7 +567,6 @@ symbols! {
         cfg_accessible,
         cfg_attr,
         cfg_attr_multi,
-        cfg_autodiff_fallback,
         cfg_boolean_literals,
         cfg_doctest,
         cfg_emscripten_wasm_eh,

compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs

@@ -1392,9 +1392,13 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         mut values: Option<ty::ParamEnvAnd<'tcx, ValuePairs<'tcx>>>,
         terr: TypeError<'tcx>,
         prefer_label: bool,
+        override_span: Option<Span>,
     ) {
-        let span = cause.span;
+        // We use `override_span` when we want the error to point at a `Span` other than
-
+        // `cause.span`. This is used in E0271, when a closure is passed in where the return type
+        // isn't what was expected. We want to point at the closure's return type (or expression),
+        // instead of the expression where the closure is passed as call argument.
+        let span = override_span.unwrap_or(cause.span);
         // For some types of errors, expected-found does not make
         // sense, so just ignore the values we were given.
         if let TypeError::CyclicTy(_) = terr {
@@ -2057,6 +2061,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             Some(param_env.and(trace.values)),
             terr,
             false,
+            None,
         );
         diag
     }

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -708,6 +708,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     None,
                     TypeError::Sorts(ty::error::ExpectedFound::new(expected_ty, ct_ty)),
                     false,
+                    None,
                 );
                 diag
             }
@@ -931,14 +932,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             }
         }
         let hir_id = self.tcx.local_def_id_to_hir_id(obligation.cause.body_id);
-        let body_id = match self.tcx.hir_node(hir_id) {
+        let Some(body_id) = self.tcx.hir_node(hir_id).body_id() else { return false };
-            hir::Node::Item(hir::Item {
+        let ControlFlow::Break(expr) =
-                kind: hir::ItemKind::Fn { body: body_id, .. }, ..
+            (FindMethodSubexprOfTry { search_span: span }).visit_body(self.tcx.hir().body(body_id))
-            }) => body_id,
-            _ => return false,
-        };
-        let ControlFlow::Break(expr) = (FindMethodSubexprOfTry { search_span: span })
-            .visit_body(self.tcx.hir().body(*body_id))
         else {
             return false;
         };
@@ -1385,9 +1381,14 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 _ => (None, error.err),
             };
 
-            let msg = values
+            let (msg, span, closure_span) = values
                 .and_then(|(predicate, normalized_term, expected_term)| {
-                    self.maybe_detailed_projection_msg(predicate, normalized_term, expected_term)
+                    self.maybe_detailed_projection_msg(
+                        obligation.cause.span,
+                        predicate,
+                        normalized_term,
+                        expected_term,
+                    )
                 })
                 .unwrap_or_else(|| {
                     let mut cx = FmtPrinter::new_with_limit(
@@ -1395,12 +1396,39 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         Namespace::TypeNS,
                         rustc_session::Limit(10),
                     );
-                    with_forced_trimmed_paths!(format!("type mismatch resolving `{}`", {
+                    (
-                        self.resolve_vars_if_possible(predicate).print(&mut cx).unwrap();
+                        with_forced_trimmed_paths!(format!("type mismatch resolving `{}`", {
-                        cx.into_buffer()
+                            self.resolve_vars_if_possible(predicate).print(&mut cx).unwrap();
-                    }))
+                            cx.into_buffer()
+                        })),
+                        obligation.cause.span,
+                        None,
+                    )
                 });
-            let mut diag = struct_span_code_err!(self.dcx(), obligation.cause.span, E0271, "{msg}");
+            let mut diag = struct_span_code_err!(self.dcx(), span, E0271, "{msg}");
+            if let Some(span) = closure_span {
+                // Mark the closure decl so that it is seen even if we are pointing at the return
+                // type or expression.
+                //
+                // error[E0271]: expected `{closure@foo.rs:41:16}` to be a closure that returns
+                //               `Unit3`, but it returns `Unit4`
+                //   --> $DIR/foo.rs:43:17
+                //    |
+                // LL |     let v = Unit2.m(
+                //    |                   - required by a bound introduced by this call
+                // ...
+                // LL |             f: |x| {
+                //    |                --- /* this span */
+                // LL |                 drop(x);
+                // LL |                 Unit4
+                //    |                 ^^^^^ expected `Unit3`, found `Unit4`
+                //    |
+                diag.span_label(span, "this closure");
+                if !span.overlaps(obligation.cause.span) {
+                    // Point at the binding corresponding to the closure where it is used.
+                    diag.span_label(obligation.cause.span, "closure used here");
+                }
+            }
 
             let secondary_span = (|| {
                 let ty::PredicateKind::Clause(ty::ClauseKind::Projection(proj)) =
@@ -1471,6 +1499,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 }),
                 err,
                 false,
+                Some(span),
             );
             self.note_obligation_cause(&mut diag, obligation);
             diag.emit()
@@ -1479,34 +1508,66 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
     fn maybe_detailed_projection_msg(
         &self,
+        mut span: Span,
         projection_term: ty::AliasTerm<'tcx>,
         normalized_ty: ty::Term<'tcx>,
         expected_ty: ty::Term<'tcx>,
-    ) -> Option<String> {
+    ) -> Option<(String, Span, Option<Span>)> {
         let trait_def_id = projection_term.trait_def_id(self.tcx);
         let self_ty = projection_term.self_ty();
 
         with_forced_trimmed_paths! {
             if self.tcx.is_lang_item(projection_term.def_id, LangItem::FnOnceOutput) {
                 let fn_kind = self_ty.prefix_string(self.tcx);
+                let (span, closure_span) = if let ty::Closure(def_id, _) = self_ty.kind() {
+                    let def_span = self.tcx.def_span(def_id);
+                    if let Some(local_def_id) = def_id.as_local()
+                        && let node = self.tcx.hir_node_by_def_id(local_def_id)
+                        && let Some(fn_decl) = node.fn_decl()
+                        && let Some(id) = node.body_id()
+                    {
+                        span = match fn_decl.output {
+                            hir::FnRetTy::Return(ty) => ty.span,
+                            hir::FnRetTy::DefaultReturn(_) => {
+                                let body = self.tcx.hir().body(id);
+                                match body.value.kind {
+                                    hir::ExprKind::Block(
+                                        hir::Block { expr: Some(expr), .. },
+                                        _,
+                                    ) => expr.span,
+                                    hir::ExprKind::Block(
+                                        hir::Block {
+                                            expr: None, stmts: [.., last], ..
+                                        },
+                                        _,
+                                    ) => last.span,
+                                    _ => body.value.span,
+                                }
+                            }
+                        };
+                    }
+                    (span, Some(def_span))
+                } else {
+                    (span, None)
+                };
                 let item = match self_ty.kind() {
                     ty::FnDef(def, _) => self.tcx.item_name(*def).to_string(),
                     _ => self_ty.to_string(),
                 };
-                Some(format!(
+                Some((format!(
                     "expected `{item}` to be a {fn_kind} that returns `{expected_ty}`, but it \
                      returns `{normalized_ty}`",
-                ))
+                ), span, closure_span))
             } else if self.tcx.is_lang_item(trait_def_id, LangItem::Future) {
-                Some(format!(
+                Some((format!(
                     "expected `{self_ty}` to be a future that resolves to `{expected_ty}`, but it \
                      resolves to `{normalized_ty}`"
-                ))
+                ), span, None))
             } else if Some(trait_def_id) == self.tcx.get_diagnostic_item(sym::Iterator) {
-                Some(format!(
+                Some((format!(
                     "expected `{self_ty}` to be an iterator that yields `{expected_ty}`, but it \
                      yields `{normalized_ty}`"
-                ))
+                ), span, None))
             } else {
                 None
             }

library/core/src/sync/atomic.rs

@@ -716,6 +716,12 @@ impl AtomicBool {
     /// AcqRel   | AcqRel  | Acquire
     /// SeqCst   | SeqCst  | SeqCst
     ///
+    /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use
+    /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`,
+    /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err`
+    /// rather than to infer success vs failure based on the value that was read.
+    ///
+    /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead.
     /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds,
     /// which allows the compiler to generate better assembly code when the compare and swap
     /// is used in a loop.
@@ -1651,6 +1657,12 @@ impl<T> AtomicPtr<T> {
     /// AcqRel   | AcqRel  | Acquire
     /// SeqCst   | SeqCst  | SeqCst
     ///
+    /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use
+    /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`,
+    /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err`
+    /// rather than to infer success vs failure based on the value that was read.
+    ///
+    /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead.
     /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds,
     /// which allows the compiler to generate better assembly code when the compare and swap
     /// is used in a loop.
@@ -2771,6 +2783,12 @@ macro_rules! atomic_int {
             /// AcqRel   | AcqRel  | Acquire
             /// SeqCst   | SeqCst  | SeqCst
             ///
+            /// `compare_and_swap` and `compare_exchange` also differ in their return type. You can use
+            /// `compare_exchange(...).unwrap_or_else(|x| x)` to recover the behavior of `compare_and_swap`,
+            /// but in most cases it is more idiomatic to check whether the return value is `Ok` or `Err`
+            /// rather than to infer success vs failure based on the value that was read.
+            ///
+            /// During migration, consider whether it makes sense to use `compare_exchange_weak` instead.
             /// `compare_exchange_weak` is allowed to fail spuriously even when the comparison succeeds,
             /// which allows the compiler to generate better assembly code when the compare and swap
             /// is used in a loop.

src/bootstrap/src/core/build_steps/compile.rs

@@ -1049,9 +1049,12 @@ pub fn rustc_cargo(
     // <https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Internal.20lint.20for.20raw.20.60print!.60.20and.20.60println!.60.3F>.
     cargo.rustflag("-Zon-broken-pipe=kill");
 
-    if builder.config.llvm_enzyme {
+    // We temporarily disable linking here as part of some refactoring.
-        cargo.rustflag("-l").rustflag("Enzyme-19");
+    // This way, people can manually use -Z llvm-plugins and -C passes=enzyme for now.
-    }
+    // In a follow-up PR, we will re-enable linking here and load the pass for them.
+    //if builder.config.llvm_enzyme {
+    //    cargo.rustflag("-l").rustflag("Enzyme-19");
+    //}
 
     // Building with protected visibility reduces the number of dynamic relocations needed, giving
     // us a faster startup time. However GNU ld < 2.40 will error if we try to link a shared object

src/doc/rustc-dev-guide/src/conventions.md

@@ -43,7 +43,7 @@ environment.
 
 ## Formatting and linting Python code
 
-The Rust repository contains quite a lof of Python code. We try to keep
+The Rust repository contains quite a lot of Python code. We try to keep
 it both linted and formatted by the [ruff][ruff] tool.
 
 When modifying Python code, use this command to format it:

src/doc/rustc/src/profile-guided-optimization.md

@@ -3,7 +3,7 @@
 `rustc` supports doing profile-guided optimization (PGO).
 This chapter describes what PGO is, what it is good for, and how it can be used.
 
-## What Is Profiled-Guided Optimization?
+## What Is Profile-Guided Optimization?
 
 The basic concept of PGO is to collect data about the typical execution of
 a program (e.g. which branches it is likely to take) and then use this data

src/doc/style-guide/src/editions.md

@@ -36,10 +36,6 @@ For a full history of changes in the Rust 2024 style edition, see the git
 history of the style guide. Notable changes in the Rust 2024 style edition
 include:
 
-- [#114764](https://github.com/rust-lang/rust/pull/114764) As the last member
-  of a delimited expression, delimited expressions are generally combinable,
-  regardless of the number of members. Previously only applied with exactly
-  one member (except for closures with explicit blocks).
 - Miscellaneous `rustfmt` bugfixes.
 - Use version-sort (sort `x8`, `x16`, `x32`, `x64`, `x128` in that order).
 - Change "ASCIIbetical" sort to Unicode-aware "non-lowercase before lowercase".

src/doc/style-guide/src/expressions.md

@@ -818,11 +818,11 @@ E.g., `&&Some(foo)` matches, `Foo(4, Bar)` does not.
 
 ## Combinable expressions
 
-When the last argument in a function call is formatted across
+Where a function call has a single argument, and that argument is formatted
-multiple-lines, format the outer call as if it were a single-line call,
+across multiple-lines, format the outer call as if it were a single-line call,
 if the result fits. Apply the same combining behaviour to any similar
 expressions which have multi-line, block-indented lists of sub-expressions
-delimited by parentheses, brackets, or braces. E.g.,
+delimited by parentheses (e.g., macros or tuple struct literals). E.g.,
 
 ```rust
 foo(bar(
@@ -848,61 +848,20 @@ let arr = [combinable(
     an_expr,
     another_expr,
 )];
-
-let x = Thing(an_expr, another_expr, match cond {
-    A => 1,
-    B => 2,
-});
-
-let x = format!("Stuff: {}", [
-    an_expr,
-    another_expr,
-]);
-
-let x = func(an_expr, another_expr, SomeStruct {
-    field: this_is_long,
-    another_field: 123,
-});
 ```
 
 Apply this behavior recursively.
 
-If the last argument is a multi-line closure with an explicit block,
+For a function with multiple arguments, if the last argument is a multi-line
-only apply the combining behavior if there are no other closure arguments.
+closure with an explicit block, there are no other closure arguments, and all
+the arguments and the first line of the closure fit on the first line, use the
+same combining behavior:
 
 ```rust
-// Combinable
 foo(first_arg, x, |param| {
     action();
     foo(param)
 })
-// Not combinable, because the closure is not the last argument
-foo(
-    first_arg,
-    |param| {
-        action();
-        foo(param)
-    },
-    whatever,
-)
-// Not combinable, because the first line of the closure does not fit
-foo(
-    first_arg,
-    x,
-    move |very_long_param_causing_line_to_overflow| -> Bar {
-        action();
-        foo(param)
-    },
-)
-// Not combinable, because there is more than one closure argument
-foo(
-    first_arg,
-    |x| x.bar(),
-    |param| {
-        action();
-        foo(param)
-    },
-)
 ```
 
 ## Ranges

src/doc/unstable-book/src/compiler-flags/autodiff.md

@@ -0,0 +1,23 @@
+# `autodiff`
+
+The tracking issue for this feature is: [#124509](https://github.com/rust-lang/rust/issues/124509).
+
+------------------------
+
+This feature allows you to differentiate functions using automatic differentiation.
+Set the `-Zautodiff=<options>` compiler flag to adjust the behaviour of the autodiff feature.
+Multiple options can be separated with a comma. Valid options are:
+
+`PrintTA` - print Type Analysis Information
+`PrintAA` - print Activity Analysis Information
+`PrintPerf` - print Performance Warnings from Enzyme
+`Print` - prints all intermediate transformations
+`PrintModBefore` - print the whole module, before running opts
+`PrintModAfterOpts` - print the whole module just before we pass it to Enzyme
+`PrintModAfterEnzyme` - print the module after Enzyme differentiated everything
+`LooseTypes` - Enzyme's loose type debug helper (can cause incorrect gradients)
+`Inline` - runs Enzyme specific Inlining
+`NoModOptAfter` - do not optimize the module after Enzyme is done
+`EnableFncOpt` - tell Enzyme to run LLVM Opts on each function it generated
+`NoVecUnroll` - do not unroll vectorized loops
+`RuntimeActivity` - allow specifying activity at runtime

src/tools/enzyme

@@ -1 +1 @@
-Subproject commit 2fe5164a2423dd67ef25e2c4fb204fd06362494b
+Subproject commit 0e5fa4a3d475f4dece489c9e06b11164f83789f5

src/tools/rustfmt/src/bin/main.rs

@@ -817,7 +817,6 @@ mod test {
         options.inline_config = HashMap::from([("version".to_owned(), "Two".to_owned())]);
         let config = get_config(None, Some(options));
         assert_eq!(config.style_edition(), StyleEdition::Edition2024);
-        assert_eq!(config.overflow_delimited_expr(), true);
     }
 
     #[nightly_only_test]
@@ -827,7 +826,6 @@ mod test {
         let config_file = Some(Path::new("tests/config/style-edition/just-version"));
         let config = get_config(config_file, Some(options));
         assert_eq!(config.style_edition(), StyleEdition::Edition2024);
-        assert_eq!(config.overflow_delimited_expr(), true);
     }
 
     #[nightly_only_test]
@@ -872,7 +870,6 @@ mod test {
         ]);
         let config = get_config(None, Some(options));
         assert_eq!(config.style_edition(), StyleEdition::Edition2024);
-        assert_eq!(config.overflow_delimited_expr(), true);
     }
 
     #[nightly_only_test]
@@ -938,7 +935,6 @@ mod test {
         options.style_edition = Some(StyleEdition::Edition2024);
         let config = get_config(None, Some(options));
         assert_eq!(config.style_edition(), StyleEdition::Edition2024);
-        assert_eq!(config.overflow_delimited_expr(), true);
     }
 
     #[nightly_only_test]
@@ -948,6 +944,8 @@ mod test {
         let config_file = Some(Path::new("tests/config/style-edition/overrides"));
         let config = get_config(config_file, Some(options));
         assert_eq!(config.style_edition(), StyleEdition::Edition2024);
+        // FIXME: this test doesn't really exercise anything, since
+        // `overflow_delimited_expr` is disabled by default in edition 2024.
         assert_eq!(config.overflow_delimited_expr(), false);
     }
 
@@ -959,7 +957,8 @@ mod test {
         options.inline_config =
             HashMap::from([("overflow_delimited_expr".to_owned(), "false".to_owned())]);
         let config = get_config(config_file, Some(options));
-        assert_eq!(config.style_edition(), StyleEdition::Edition2024);
+        // FIXME: this test doesn't really exercise anything, since
+        // `overflow_delimited_expr` is disabled by default in edition 2024.
         assert_eq!(config.overflow_delimited_expr(), false);
     }
 }

src/tools/rustfmt/src/config/mod.rs

@@ -848,7 +848,7 @@ binop_separator = "Front"
 remove_nested_parens = true
 combine_control_expr = true
 short_array_element_width_threshold = 10
-overflow_delimited_expr = true
+overflow_delimited_expr = false
 struct_field_align_threshold = 0
 enum_discrim_align_threshold = 0
 match_arm_blocks = true

src/tools/rustfmt/src/config/options.rs

@@ -627,7 +627,7 @@ config_option_with_style_edition_default!(
     RemoveNestedParens, bool, _ => true;
     CombineControlExpr, bool, _ => true;
     ShortArrayElementWidthThreshold, usize, _ => 10;
-    OverflowDelimitedExpr, bool, Edition2024 => true, _ => false;
+    OverflowDelimitedExpr, bool, _ => false;
     StructFieldAlignThreshold, usize, _ => 0;
     EnumDiscrimAlignThreshold, usize, _ => 0;
     MatchArmBlocks, bool, _ => true;
@@ -644,7 +644,7 @@ config_option_with_style_edition_default!(
     BlankLinesLowerBound, usize, _ => 0;
     EditionConfig, Edition, _ => Edition::Edition2015;
     StyleEditionConfig, StyleEdition,
-        Edition2024 =>  StyleEdition::Edition2024, _ => StyleEdition::Edition2015;
+        Edition2024 => StyleEdition::Edition2024, _ => StyleEdition::Edition2015;
     VersionConfig, Version, Edition2024 => Version::Two, _ => Version::One;
     InlineAttributeWidth, usize, _ => 0;
     FormatGeneratedFiles, bool, _ => true;

src/tools/rustfmt/tests/target/configs/style_edition/overflow_delim_expr_2024.rs

@@ -25,10 +25,13 @@ fn combine_blocklike() {
         y: value2,
     });
 
-    do_thing(x, Bar {
+    do_thing(
-        x: value,
+        x,
-        y: value2,
+        Bar {
-    });
+            x: value,
+            y: value2,
+        },
+    );
 
     do_thing(
         x,
@@ -46,12 +49,15 @@ fn combine_blocklike() {
         value4_with_longer_name,
     ]);
 
-    do_thing(x, &[
+    do_thing(
-        value_with_longer_name,
+        x,
-        value2_with_longer_name,
+        &[
-        value3_with_longer_name,
+            value_with_longer_name,
-        value4_with_longer_name,
+            value2_with_longer_name,
-    ]);
+            value3_with_longer_name,
+            value4_with_longer_name,
+        ],
+    );
 
     do_thing(
         x,
@@ -71,12 +77,15 @@ fn combine_blocklike() {
         value4_with_longer_name,
     ]);
 
-    do_thing(x, vec![
+    do_thing(
-        value_with_longer_name,
+        x,
-        value2_with_longer_name,
+        vec![
-        value3_with_longer_name,
+            value_with_longer_name,
-        value4_with_longer_name,
+            value2_with_longer_name,
-    ]);
+            value3_with_longer_name,
+            value4_with_longer_name,
+        ],
+    );
 
     do_thing(
         x,
@@ -99,22 +108,28 @@ fn combine_blocklike() {
 }
 
 fn combine_struct_sample() {
-    let identity = verify(&ctx, VerifyLogin {
+    let identity = verify(
-        type_: LoginType::Username,
+        &ctx,
-        username: args.username.clone(),
+        VerifyLogin {
-        password: Some(args.password.clone()),
+            type_: LoginType::Username,
-        domain: None,
+            username: args.username.clone(),
-    })?;
+            password: Some(args.password.clone()),
+            domain: None,
+        },
+    )?;
 }
 
 fn combine_macro_sample() {
     rocket::ignite()
-        .mount("/", routes![
+        .mount(
-            http::auth::login,
+            "/",
-            http::auth::logout,
+            routes![
-            http::cors::options,
+                http::auth::login,
-            http::action::dance,
+                http::auth::logout,
-            http::action::sleep,
+                http::cors::options,
-        ])
+                http::action::dance,
+                http::action::sleep,
+            ],
+        )
         .launch();
 }

tests/ui/async-await/dont-ice-for-type-mismatch-in-closure-in-async.stderr

@@ -21,18 +21,14 @@ LL |         true
               found type `bool`
 
 error[E0271]: expected `{closure@dont-ice-for-type-mismatch-in-closure-in-async.rs:6:10}` to be a closure that returns `bool`, but it returns `Option<()>`
-  --> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:6:10
+  --> $DIR/dont-ice-for-type-mismatch-in-closure-in-async.rs:6:16
    |
-LL |       call(|| -> Option<()> {
+LL |     call(|| -> Option<()> {
-   |  _____----_^
+   |     ---- ------^^^^^^^^^^
-   | |     |
+   |     |    |     |
-   | |     required by a bound introduced by this call
+   |     |    |     expected `bool`, found `Option<()>`
-LL | |
+   |     |    this closure
-LL | |         if true {
+   |     required by a bound introduced by this call
-LL | |             false
-...  |
-LL | |     })
-   | |_____^ expected `bool`, found `Option<()>`
    |
    = note: expected type `bool`
               found enum `Option<()>`

tests/ui/closures/return-type-doesnt-match-bound.rs

@@ -0,0 +1,25 @@
+use std::error::Error;
+use std::process::exit;
+
+fn foo<F>(f: F) -> ()
+where
+    F: FnOnce() -> Result<(), Box<dyn Error>>,
+{
+    f().or_else(|e| -> ! { //~ ERROR to be a closure that returns
+        eprintln!("{:?}", e);
+        exit(1)
+    });
+}
+
+fn bar<F>(f: F) -> ()
+where
+    F: FnOnce() -> Result<(), Box<dyn Error>>,
+{
+    let c = |e| -> ! { //~ ERROR to be a closure that returns
+        eprintln!("{:?}", e);
+        exit(1)
+    };
+    f().or_else(c);
+}
+
+fn main() {}

tests/ui/closures/return-type-doesnt-match-bound.stderr

@@ -0,0 +1,37 @@
+error[E0271]: expected `{closure@return-type-doesnt-match-bound.rs:8:17}` to be a closure that returns `Result<(), _>`, but it returns `!`
+  --> $DIR/return-type-doesnt-match-bound.rs:8:24
+   |
+LL |     f().or_else(|e| -> ! {
+   |         ------- -------^
+   |         |       |      |
+   |         |       |      expected `Result<(), _>`, found `!`
+   |         |       this closure
+   |         required by a bound introduced by this call
+   |
+   = note: expected enum `Result<(), _>`
+              found type `!`
+note: required by a bound in `Result::<T, E>::or_else`
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+
+error[E0271]: expected `{closure@return-type-doesnt-match-bound.rs:18:13}` to be a closure that returns `Result<(), _>`, but it returns `!`
+  --> $DIR/return-type-doesnt-match-bound.rs:18:20
+   |
+LL |     let c = |e| -> ! {
+   |             -------^
+   |             |      |
+   |             |      expected `Result<(), _>`, found `!`
+   |             this closure
+...
+LL |     f().or_else(c);
+   |         ------- - closure used here
+   |         |
+   |         required by a bound introduced by this call
+   |
+   = note: expected enum `Result<(), _>`
+              found type `!`
+note: required by a bound in `Result::<T, E>::or_else`
+  --> $SRC_DIR/core/src/result.rs:LL:COL
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0271`.

tests/ui/diagnostic-width/long-E0308.ascii.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:46:9
+  --> $DIR/long-E0308.rs:48:9
    |
 LL |        let x: Atype<
    |  _____________-
@@ -20,11 +20,11 @@ LL |  |     ))))))))))))))))))))))))))))));
    |
    = note: expected struct `Atype<Btype<..., ...>, ...>`
                 found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:59:26
+  --> $DIR/long-E0308.rs:61:26
    |
 LL |       ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
    |  __________________________^
@@ -36,11 +36,11 @@ LL | |     ))))))))))))))))))))))));
    |
    = note: expected enum `Option<Result<..., ...>>`
               found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:90:9
+  --> $DIR/long-E0308.rs:92:9
    |
 LL |       let x: Atype<
    |  ____________-
@@ -56,11 +56,11 @@ LL | |     > = ();
    |
    = note: expected struct `Atype<Btype<..., ...>, ...>`
            found unit type `()`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:93:17
+  --> $DIR/long-E0308.rs:95:17
    |
 LL |       let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
    |  ____________--___^
@@ -74,7 +74,7 @@ LL | |     ))))))))))))))))))))))));
    |
    = note: expected unit type `()`
                    found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error: aborting due to 4 previous errors

tests/ui/diagnostic-width/long-E0308.rs

@@ -1,7 +1,9 @@
 //@ revisions: ascii unicode
 //@[ascii] compile-flags: --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
 //@[unicode] compile-flags: -Zunstable-options --json=diagnostic-unicode --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
-//@ normalize-stderr: "long-type-\d+" -> "long-type-hash"
+
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type-\d+.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type-hash.txt'"
 
 mod a {
     // Force the "short path for unique types" machinery to trip up

tests/ui/diagnostic-width/long-E0308.unicode.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-   ╭▸ $DIR/long-E0308.rs:46:9
+   ╭▸ $DIR/long-E0308.rs:48:9
    │
 LL │        let x: Atype<
    │ ┌─────────────┘
@@ -20,11 +20,11 @@ LL │  ┃     ))))))))))))))))))))))))))))));
    │
    ├ note: expected struct `Atype<Btype<..., ...>, ...>`
    │            found enum `Result<Result<..., ...>, ...>`
-   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    ╰ note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-   ╭▸ $DIR/long-E0308.rs:59:26
+   ╭▸ $DIR/long-E0308.rs:61:26
    │
 LL │       ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(…
    │ ┏━━━━━━━━━━━━━━━━━━━━━━━━━━┛
@@ -36,11 +36,11 @@ LL │ ┃     ))))))))))))))))))))))));
    │
    ├ note: expected enum `Option<Result<..., ...>>`
    │          found enum `Result<Result<..., ...>, ...>`
-   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    ╰ note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-   ╭▸ $DIR/long-E0308.rs:90:9
+   ╭▸ $DIR/long-E0308.rs:92:9
    │
 LL │       let x: Atype<
    │ ┌────────────┘
@@ -56,11 +56,11 @@ LL │ │     > = ();
    │
    ├ note: expected struct `Atype<Btype<..., ...>, ...>`
    │       found unit type `()`
-   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    ╰ note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-   ╭▸ $DIR/long-E0308.rs:93:17
+   ╭▸ $DIR/long-E0308.rs:95:17
    │
 LL │       let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(…
    │ ┏━━━━━━━━━━━━┬─━━━┛
@@ -74,7 +74,7 @@ LL │ ┃     ))))))))))))))))))))))));
    │
    ├ note: expected unit type `()`
    │               found enum `Result<Result<..., ...>, ...>`
-   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    ╰ note: consider using `--verbose` to print the full type name to the console
 
 error: aborting due to 4 previous errors

tests/ui/diagnostic-width/non-copy-type-moved.rs

@@ -1,5 +1,7 @@
 //@ compile-flags: --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
-//@ normalize-stderr: "long-type-\d+" -> "long-type-hash"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type-\d+.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type-hash.txt'"
+
 type A = (String, String, String, String);
 type B = (A, A, A, A);
 type C = (B, B, B, B);

tests/ui/diagnostic-width/non-copy-type-moved.stderr

@@ -1,5 +1,5 @@
 error[E0382]: use of moved value: `x`
-  --> $DIR/non-copy-type-moved.rs:14:14
+  --> $DIR/non-copy-type-moved.rs:16:14
    |
 LL | fn foo(x: D) {
    |        - move occurs because `x` has type `((..., ..., ..., ...), ..., ..., ...)`, which does not implement the `Copy` trait
@@ -8,7 +8,7 @@ LL |     let _a = x;
 LL |     let _b = x;
    |              ^ value used here after move
    |
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/non-copy-type-moved/non-copy-type-moved.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 help: consider cloning the value if the performance cost is acceptable
    |

tests/ui/diagnostic-width/secondary-label-with-long-type.rs

@@ -1,5 +1,7 @@
 //@ compile-flags: --diagnostic-width=100 -Zwrite-long-types-to-disk=yes
-//@ normalize-stderr: "long-type-\d+" -> "long-type-hash"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type-\d+.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type-hash.txt'"
+
 type A = (i32, i32, i32, i32);
 type B = (A, A, A, A);
 type C = (B, B, B, B);

tests/ui/diagnostic-width/secondary-label-with-long-type.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/secondary-label-with-long-type.rs:9:9
+  --> $DIR/secondary-label-with-long-type.rs:11:9
    |
 LL |     let () = x;
    |         ^^   - this expression has type `((..., ..., ..., ...), ..., ..., ...)`
@@ -8,7 +8,7 @@ LL |     let () = x;
    |
    = note:  expected tuple `((..., ..., ..., ...), ..., ..., ...)`
            found unit type `()`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/secondary-label-with-long-type/secondary-label-with-long-type.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error: aborting due to 1 previous error

tests/ui/higher-ranked/trait-bounds/issue-62203-hrtb-ice.rs

@@ -36,12 +36,10 @@ trait Ty<'a> {
 
 fn main() {
     let v = Unit2.m(
-        L {
+        L { //~ ERROR type mismatch
-            //~^ ERROR to be a closure that returns `Unit3`, but it returns `Unit4`
-            //~| ERROR type mismatch
             f: |x| {
                 drop(x);
-                Unit4
+                Unit4 //~ ERROR to be a closure that returns `Unit3`, but it returns `Unit4`
             },
         },
     );

tests/ui/higher-ranked/trait-bounds/issue-62203-hrtb-ice.stderr

@@ -1,16 +1,15 @@
-error[E0271]: type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:42:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
+error[E0271]: type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:40:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
   --> $DIR/issue-62203-hrtb-ice.rs:39:9
    |
 LL |       let v = Unit2.m(
    |                     - required by a bound introduced by this call
 LL | /         L {
-LL | |
-LL | |
 LL | |             f: |x| {
-...  |
+LL | |                 drop(x);
+LL | |                 Unit4
 LL | |             },
 LL | |         },
-   | |_________^ type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:42:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
+   | |_________^ type mismatch resolving `<L<{closure@issue-62203-hrtb-ice.rs:40:16}> as T0<'r, (&u8,)>>::O == <_ as Ty<'r>>::V`
    |
 note: expected this to be `<_ as Ty<'_>>::V`
   --> $DIR/issue-62203-hrtb-ice.rs:21:14
@@ -30,21 +29,19 @@ LL |     where
 LL |         F: for<'r> T0<'r, (<Self as Ty<'r>>::V,), O = <B as Ty<'r>>::V>,
    |                                                   ^^^^^^^^^^^^^^^^^^^^ required by this bound in `T1::m`
 
-error[E0271]: expected `{closure@issue-62203-hrtb-ice.rs:42:16}` to be a closure that returns `Unit3`, but it returns `Unit4`
+error[E0271]: expected `{closure@issue-62203-hrtb-ice.rs:40:16}` to be a closure that returns `Unit3`, but it returns `Unit4`
-  --> $DIR/issue-62203-hrtb-ice.rs:39:9
+  --> $DIR/issue-62203-hrtb-ice.rs:42:17
    |
-LL |       let v = Unit2.m(
+LL |     let v = Unit2.m(
-   |                     - required by a bound introduced by this call
+   |                   - required by a bound introduced by this call
-LL | /         L {
+LL |         L {
-LL | |
+LL |             f: |x| {
-LL | |
+   |                --- this closure
-LL | |             f: |x| {
+LL |                 drop(x);
-...  |
+LL |                 Unit4
-LL | |             },
+   |                 ^^^^^ expected `Unit3`, found `Unit4`
-LL | |         },
-   | |_________^ expected `Unit3`, found `Unit4`
    |
-note: required for `L<{closure@$DIR/issue-62203-hrtb-ice.rs:42:16: 42:19}>` to implement `for<'r> T0<'r, (&'r u8,)>`
+note: required for `L<{closure@$DIR/issue-62203-hrtb-ice.rs:40:16: 40:19}>` to implement `for<'r> T0<'r, (&'r u8,)>`
   --> $DIR/issue-62203-hrtb-ice.rs:17:16
    |
 LL | impl<'a, A, T> T0<'a, A> for L<T>

tests/ui/impl-trait/in-trait/dont-consider-unconstrained-rpitits.rs

@@ -0,0 +1,14 @@
+// There's a suggestion that turns `Iterator<u32>` into `Iterator<Item = u32>`
+// if we have more generics than the trait wants. Let's not consider RPITITs
+// for this, since that makes no sense right now.
+
+trait Foo {
+    fn bar(self) -> impl Sized;
+}
+
+impl Foo<u8> for () {
+    //~^ ERROR trait takes 0 generic arguments but 1 generic argument was supplied
+    fn bar(self) -> impl Sized {}
+}
+
+fn main() {}

tests/ui/impl-trait/in-trait/dont-consider-unconstrained-rpitits.stderr

@@ -0,0 +1,17 @@
+error[E0107]: trait takes 0 generic arguments but 1 generic argument was supplied
+  --> $DIR/dont-consider-unconstrained-rpitits.rs:9:6
+   |
+LL | impl Foo<u8> for () {
+   |      ^^^---- help: remove the unnecessary generics
+   |      |
+   |      expected 0 generic arguments
+   |
+note: trait defined here, with 0 generic parameters
+  --> $DIR/dont-consider-unconstrained-rpitits.rs:5:7
+   |
+LL | trait Foo {
+   |       ^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0107`.

tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.rs

@@ -3,6 +3,9 @@
 //@ error-pattern: reached the recursion limit while instantiating
 //@ error-pattern: reached the recursion limit finding the struct tail
 
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
+
 // Regression test for #114484: This used to ICE during monomorphization, because we treated
 // `<VirtualWrapper<...> as Pointee>::Metadata` as a rigid projection after reaching the recursion
 // limit when finding the struct tail.

tests/ui/infinite/infinite-instantiation-struct-tail-ice-114484.stderr

@@ -18,7 +18,7 @@ error: reached the recursion limit finding the struct tail for `[u8; 256]`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<SomeData<256>, 0>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:26:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:29:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -43,7 +43,7 @@ error: reached the recursion limit finding the struct tail for `SomeData<256>`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<SomeData<256>, 0>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:26:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:29:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -68,7 +68,7 @@ error: reached the recursion limit finding the struct tail for `VirtualWrapper<S
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 note: the above error was encountered while instantiating `fn virtualize_my_trait::<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<SomeData<256>, 0>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>, 1>>`
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:26:18
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:29:18
    |
 LL |         unsafe { virtualize_my_trait(L, self) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -76,11 +76,11 @@ LL |         unsafe { virtualize_my_trait(L, self) }
 error: reached the recursion limit while instantiating `<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<VirtualWrapper<..., 1>, 1>, 1>, 1>, 1> as MyTrait>::virtualize`
    |
 note: `<VirtualWrapper<T, L> as MyTrait>::virtualize` defined here
-  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:25:5
+  --> $DIR/infinite-instantiation-struct-tail-ice-114484.rs:28:5
    |
 LL |     fn virtualize(&self) -> &dyn MyTrait {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/infinite/infinite-instantiation-struct-tail-ice-114484/infinite-instantiation-struct-tail-ice-114484.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 13 previous errors
 

tests/ui/infinite/infinite-instantiation.rs

@@ -1,5 +1,6 @@
 //@ build-fail
-//@ normalize-stderr: ".nll/" -> "/"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
 
 trait ToOpt: Sized {
     fn to_option(&self) -> Option<Self>;

tests/ui/infinite/infinite-instantiation.stderr

@@ -1,15 +1,15 @@
 error: reached the recursion limit while instantiating `function::<Option<Option<Option<Option<Option<...>>>>>>`
-  --> $DIR/infinite-instantiation.rs:22:9
+  --> $DIR/infinite-instantiation.rs:23:9
    |
 LL |         function(counter - 1, t.to_option());
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `function` defined here
-  --> $DIR/infinite-instantiation.rs:20:1
+  --> $DIR/infinite-instantiation.rs:21:1
    |
 LL | fn function<T:ToOpt + Clone>(counter: usize, t: T) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/infinite/infinite-instantiation/infinite-instantiation.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 1 previous error
 

tests/ui/issues/issue-37311-type-length-limit/issue-37311.rs

@@ -1,5 +1,6 @@
 //@ build-fail
-//@ normalize-stderr: ".nll/" -> "/"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
 
 trait Mirror {
     type Image;

tests/ui/issues/issue-37311-type-length-limit/issue-37311.stderr

@@ -1,15 +1,15 @@
 error: reached the recursion limit while instantiating `<(&(&(..., ...), ...), ...) as Foo>::recurse`
-  --> $DIR/issue-37311.rs:17:9
+  --> $DIR/issue-37311.rs:18:9
    |
 LL |         (self, self).recurse();
    |         ^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `<T as Foo>::recurse` defined here
-  --> $DIR/issue-37311.rs:16:5
+  --> $DIR/issue-37311.rs:17:5
    |
 LL |     fn recurse(&self) {
    |     ^^^^^^^^^^^^^^^^^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-37311-type-length-limit/issue-37311/issue-37311.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 1 previous error
 

tests/ui/issues/issue-67552.rs

@@ -1,6 +1,7 @@
 //@ build-fail
 //@ compile-flags: -Copt-level=0
-//@ normalize-stderr: ".nll/" -> "/"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
 
 fn main() {
     rec(Empty);

tests/ui/issues/issue-67552.stderr

@@ -1,17 +1,17 @@
 error: reached the recursion limit while instantiating `rec::<&mut &mut &mut &mut &mut ...>`
-  --> $DIR/issue-67552.rs:29:9
+  --> $DIR/issue-67552.rs:30:9
    |
 LL |         rec(identity(&mut it))
    |         ^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `rec` defined here
-  --> $DIR/issue-67552.rs:22:1
+  --> $DIR/issue-67552.rs:23:1
    |
 LL | / fn rec<T>(mut it: T)
 LL | | where
 LL | |     T: Iterator,
    | |________________^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-67552/issue-67552.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 1 previous error
 

tests/ui/issues/issue-8727.rs

@@ -2,7 +2,8 @@
 // recursions.
 
 //@ build-fail
-//@ normalize-stderr: ".nll/" -> "/"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
 
 fn generic<T>() { //~ WARN function cannot return without recursing
     generic::<Option<T>>();

tests/ui/issues/issue-8727.stderr

@@ -1,5 +1,5 @@
 warning: function cannot return without recursing
-  --> $DIR/issue-8727.rs:7:1
+  --> $DIR/issue-8727.rs:8:1
    |
 LL | fn generic<T>() {
    | ^^^^^^^^^^^^^^^ cannot return without recursing
@@ -10,17 +10,17 @@ LL |     generic::<Option<T>>();
    = note: `#[warn(unconditional_recursion)]` on by default
 
 error: reached the recursion limit while instantiating `generic::<Option<Option<Option<Option<Option<...>>>>>>`
-  --> $DIR/issue-8727.rs:8:5
+  --> $DIR/issue-8727.rs:9:5
    |
 LL |     generic::<Option<T>>();
    |     ^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `generic` defined here
-  --> $DIR/issue-8727.rs:7:1
+  --> $DIR/issue-8727.rs:8:1
    |
 LL | fn generic<T>() {
    | ^^^^^^^^^^^^^^^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-8727/issue-8727.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 1 previous error; 1 warning emitted
 

tests/ui/never_type/fallback-closure-wrap.fallback.stderr

@@ -1,16 +1,15 @@
 error[E0271]: expected `{closure@fallback-closure-wrap.rs:18:40}` to be a closure that returns `()`, but it returns `!`
-  --> $DIR/fallback-closure-wrap.rs:18:31
+  --> $DIR/fallback-closure-wrap.rs:19:9
    |
-LL |       let error = Closure::wrap(Box::new(move || {
+LL |     let error = Closure::wrap(Box::new(move || {
-   |  _______________________________^
+   |                                        ------- this closure
-LL | |
+LL |         panic!("Can't connect to server.");
-LL | |         panic!("Can't connect to server.");
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `!`
-LL | |     }) as Box<dyn FnMut()>);
-   | |______^ expected `()`, found `!`
    |
    = note: expected unit type `()`
                    found type `!`
    = note: required for the cast from `Box<{closure@$DIR/fallback-closure-wrap.rs:18:40: 18:47}>` to `Box<dyn FnMut()>`
+   = note: this error originates in the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error
 

tests/ui/never_type/fallback-closure-wrap.rs

@@ -16,8 +16,8 @@ use std::marker::PhantomData;
 
 fn main() {
     let error = Closure::wrap(Box::new(move || {
-        //[fallback]~^ to be a closure that returns `()`, but it returns `!`
         panic!("Can't connect to server.");
+        //[fallback]~^ to be a closure that returns `()`, but it returns `!`
     }) as Box<dyn FnMut()>);
 }
 

tests/ui/recursion/recursion.rs

@@ -1,6 +1,7 @@
 //@ build-fail
 //@ compile-flags:-C overflow-checks=off
-//@ normalize-stderr: ".nll/" -> "/"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
 
 enum Nil {NilValue}
 struct Cons<T> {head:isize, tail:T}

tests/ui/recursion/recursion.stderr

@@ -1,15 +1,15 @@
 error: reached the recursion limit while instantiating `test::<Cons<Cons<Cons<Cons<Cons<...>>>>>>`
-  --> $DIR/recursion.rs:18:11
+  --> $DIR/recursion.rs:19:11
    |
 LL |     _ => {test (n-1, i+1, Cons {head:2*i+1, tail:first}, Cons{head:i*i, tail:second})}
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `test` defined here
-  --> $DIR/recursion.rs:16:1
+  --> $DIR/recursion.rs:17:1
    |
 LL | fn test<T:Dot> (n:isize, i:isize, first:T, second:T) ->isize {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: the full type name has been written to '$TEST_BUILD_DIR/recursion/recursion/recursion.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: aborting due to 1 previous error
 

tests/ui/traits/on_unimplemented_long_types.rs

@@ -1,5 +1,6 @@
 //@ compile-flags: --diagnostic-width=60 -Z write-long-types-to-disk=yes
-//@ normalize-stderr: "long-type-\d+" -> "long-type-hash"
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type-\d+.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type-hash.txt'"
 
 pub fn foo() -> impl std::fmt::Display {
     //~^ ERROR doesn't implement `std::fmt::Display`

tests/ui/traits/on_unimplemented_long_types.stderr

@@ -1,5 +1,5 @@
 error[E0277]: `Option<Option<Option<...>>>` doesn't implement `std::fmt::Display`
-  --> $DIR/on_unimplemented_long_types.rs:4:17
+  --> $DIR/on_unimplemented_long_types.rs:5:17
    |
 LL |   pub fn foo() -> impl std::fmt::Display {
    |                   ^^^^^^^^^^^^^^^^^^^^^^ `Option<Option<Option<...>>>` cannot be formatted with the default formatter
@@ -13,11 +13,11 @@ LL | |         ))))))))))),
 LL | |     )))))))))))
    | |_______________- return type was inferred to be `Option<Option<Option<...>>>` here
    |
-   = note: the full name for the type has been written to '$TEST_BUILD_DIR/traits/on_unimplemented_long_types/on_unimplemented_long_types.long-type-hash.txt'
+   = note: the full name for the type has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
    = help: the trait `std::fmt::Display` is not implemented for `Option<Option<Option<...>>>`
    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
-   = note: the full name for the type has been written to '$TEST_BUILD_DIR/traits/on_unimplemented_long_types/on_unimplemented_long_types.long-type-hash.txt'
+   = note: the full name for the type has been written to '$TEST_BUILD_DIR/$FILE.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error: aborting due to 1 previous error

tests/ui/type_length_limit.rs

@@ -2,6 +2,9 @@
 //@ compile-flags: -Copt-level=0 -Zenforce-type-length-limit
 //~^^ ERROR reached the type-length limit
 
+// The regex below normalizes the long type file name to make it suitable for compare-modes.
+//@ normalize-stderr: "'\$TEST_BUILD_DIR/.*\.long-type.txt'" -> "'$$TEST_BUILD_DIR/$$FILE.long-type.txt'"
+
 // Test that the type length limit can be changed.
 // The exact type depends on optimizations, so disable them.
 

tests/ui/type_length_limit.stderr

@@ -1,11 +1,11 @@
 error: reached the type-length limit while instantiating `std::mem::drop::<Option<((((..., ..., ...), ..., ...), ..., ...), ..., ...)>>`
-  --> $DIR/type_length_limit.rs:32:5
+  --> $DIR/type_length_limit.rs:35:5
    |
 LL |     drop::<Option<A>>(None);
    |     ^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding a `#![type_length_limit="4010"]` attribute to your crate
-   = note: the full type name has been written to '$TEST_BUILD_DIR/type_length_limit/type_length_limit.long-type.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/$FILE.long-type.txt'
 
 error: reached the type-length limit while instantiating `<{closure@rt::lang_start<()>::{closure#0}} as FnMut<()>>::call_mut`
    |