Auto merge of #120619 - compiler-errors:param, r=lcnr

Assert that params with the same *index* have the same *name*

Found this bug when trying to build libcore with the new solver, since it will canonicalize two params with the same index into *different* placeholders if those params differ by name.

compiler/rustc_hir_analysis/src/check/intrinsic.rs

@@ -12,7 +12,7 @@ use rustc_errors::{codes::*, struct_span_code_err, DiagnosticMessage};
 use rustc_hir as hir;
 use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::symbol::{kw, sym, Symbol};
+use rustc_span::symbol::{kw, sym};
 use rustc_target::spec::abi::Abi;
 
 fn equate_intrinsic_type<'tcx>(
@@ -133,7 +133,17 @@ pub fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: DefId) -> hir
 /// Remember to add all intrinsics here, in `compiler/rustc_codegen_llvm/src/intrinsic.rs`,
 /// and in `library/core/src/intrinsics.rs`.
 pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
-    let param = |n| Ty::new_param(tcx, n, Symbol::intern(&format!("P{n}")));
+    let generics = tcx.generics_of(it.owner_id);
+    let param = |n| {
+        if let Some(&ty::GenericParamDef {
+            name, kind: ty::GenericParamDefKind::Type { .. }, ..
+        }) = generics.opt_param_at(n as usize, tcx)
+        {
+            Ty::new_param(tcx, n, name)
+        } else {
+            Ty::new_error_with_message(tcx, tcx.def_span(it.owner_id), "expected param")
+        }
+    };
     let intrinsic_id = it.owner_id.to_def_id();
     let intrinsic_name = tcx.item_name(intrinsic_id);
     let name_str = intrinsic_name.as_str();
@@ -478,9 +488,16 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
 /// Type-check `extern "platform-intrinsic" { ... }` functions.
 pub fn check_platform_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
+    let generics = tcx.generics_of(it.owner_id);
     let param = |n| {
-        let name = Symbol::intern(&format!("P{n}"));
-        Ty::new_param(tcx, n, name)
+        if let Some(&ty::GenericParamDef {
+            name, kind: ty::GenericParamDefKind::Type { .. }, ..
+        }) = generics.opt_param_at(n as usize, tcx)
+        {
+            Ty::new_param(tcx, n, name)
+        } else {
+            Ty::new_error_with_message(tcx, tcx.def_span(it.owner_id), "expected param")
+        }
     };
 
     let name = it.ident.name;

compiler/rustc_middle/src/ty/relate.rs

@@ -435,7 +435,10 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
             Ok(a)
         }
 
-        (ty::Param(a_p), ty::Param(b_p)) if a_p.index == b_p.index => Ok(a),
+        (ty::Param(a_p), ty::Param(b_p)) if a_p.index == b_p.index => {
+            debug_assert_eq!(a_p.name, b_p.name, "param types with same index differ in name");
+            Ok(a)
+        }
 
         (ty::Placeholder(p1), ty::Placeholder(p2)) if p1 == p2 => Ok(a),
 
@@ -593,7 +596,10 @@ pub fn structurally_relate_consts<'tcx, R: TypeRelation<'tcx>>(
         (ty::ConstKind::Error(_), _) => return Ok(a),
         (_, ty::ConstKind::Error(_)) => return Ok(b),
 
-        (ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) => a_p.index == b_p.index,
+        (ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) if a_p.index == b_p.index => {
+            debug_assert_eq!(a_p.name, b_p.name, "param types with same index differ in name");
+            true
+        }
         (ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) => p1 == p2,
         (ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => a_val == b_val,
 

compiler/rustc_mir_transform/src/shim.rs

@@ -447,16 +447,13 @@ fn build_thread_local_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'t
 fn build_clone_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> Body<'tcx> {
     debug!("build_clone_shim(def_id={:?})", def_id);
 
-    let param_env = tcx.param_env_reveal_all_normalized(def_id);
-
     let mut builder = CloneShimBuilder::new(tcx, def_id, self_ty);
-    let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env);
 
     let dest = Place::return_place();
     let src = tcx.mk_place_deref(Place::from(Local::new(1 + 0)));
 
     match self_ty.kind() {
-        _ if is_copy => builder.copy_shim(),
+        ty::FnDef(..) | ty::FnPtr(_) => builder.copy_shim(),
         ty::Closure(_, args) => builder.tuple_like_shim(dest, src, args.as_closure().upvar_tys()),
         ty::Tuple(..) => builder.tuple_like_shim(dest, src, self_ty.tuple_fields()),
         ty::Coroutine(coroutine_def_id, args) => {

compiler/rustc_ty_utils/src/instance.rs

@@ -209,10 +209,8 @@ fn resolve_associated_item<'tcx>(
                 let name = tcx.item_name(trait_item_id);
                 if name == sym::clone {
                     let self_ty = trait_ref.self_ty();
-
-                    let is_copy = self_ty.is_copy_modulo_regions(tcx, param_env);
                     match self_ty.kind() {
-                        _ if is_copy => (),
+                        ty::FnDef(..) | ty::FnPtr(_) => (),
                         ty::Coroutine(..)
                         | ty::CoroutineWitness(..)
                         | ty::Closure(..)