Auto merge of #85110 - RalfJung:no-rustc_args_required_const, r=oli-obk

Remove rustc_args_required_const attribute

Now that stdarch no longer needs it (thanks `@Amanieu!),` we can kill the `rustc_args_required_const` attribute. This means that lifetime extension of references to temporaries is the only remaining job that promotion is performing. :-)

r? `@oli-obk`
Fixes https://github.com/rust-lang/rust/issues/69493

compiler/rustc_codegen_ssa/src/mir/rvalue.rs

@@ -14,7 +14,6 @@ use rustc_middle::ty::cast::{CastTy, IntTy};
 use rustc_middle::ty::layout::HasTyCtxt;
 use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt};
 use rustc_span::source_map::{Span, DUMMY_SP};
-use rustc_span::symbol::sym;
 use rustc_target::abi::{Abi, Int, LayoutOf, Variants};
 
 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
@@ -187,9 +186,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => {
                         match *operand.layout.ty.kind() {
                             ty::FnDef(def_id, substs) => {
-                                if bx.cx().tcx().has_attr(def_id, sym::rustc_args_required_const) {
-                                    bug!("reifying a fn ptr that requires const arguments");
-                                }
                                 let instance = ty::Instance::resolve_for_fn_ptr(
                                     bx.tcx(),
                                     ty::ParamEnv::reveal_all(),

compiler/rustc_feature/src/builtin_attrs.rs

@@ -469,7 +469,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // ==========================================================================
 
     rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
-    rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
     rustc_attr!(rustc_legacy_const_generics, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
 
     // ==========================================================================

compiler/rustc_mir/src/interpret/cast.rs

@@ -7,7 +7,6 @@ use rustc_middle::mir::CastKind;
 use rustc_middle::ty::adjustment::PointerCast;
 use rustc_middle::ty::layout::{IntegerExt, TyAndLayout};
 use rustc_middle::ty::{self, FloatTy, Ty, TypeAndMut};
-use rustc_span::symbol::sym;
 use rustc_target::abi::{Integer, LayoutOf, Variants};
 
 use super::{
@@ -49,13 +48,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         // All reifications must be monomorphic, bail out otherwise.
                         ensure_monomorphic_enough(*self.tcx, src.layout.ty)?;
 
-                        if self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
-                            span_bug!(
-                                self.cur_span(),
-                                "reifying a fn ptr that requires const arguments"
-                            );
-                        }
-
                         let instance = ty::Instance::resolve_for_fn_ptr(
                             *self.tcx,
                             self.param_env,

compiler/rustc_mir/src/interpret/intern.rs

@@ -305,7 +305,6 @@ where
     let base_intern_mode = match intern_kind {
         InternKind::Static(mutbl) => InternMode::Static(mutbl),
         // `Constant` includes array lengths.
-        // `Promoted` includes non-`Copy` array initializers and `rustc_args_required_const` arguments.
         InternKind::Constant | InternKind::Promoted => InternMode::Const,
     };
 

compiler/rustc_mir/src/transform/lower_intrinsics.rs

@@ -5,6 +5,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::symbol::{sym, Symbol};
+use rustc_span::Span;
 use rustc_target::spec::abi::Abi;
 
 pub struct LowerIntrinsics;
@@ -119,6 +120,9 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
                             terminator.kind = TerminatorKind::Goto { target };
                         }
                     }
+                    _ if intrinsic_name.as_str().starts_with("simd_shuffle") => {
+                        validate_simd_shuffle(tcx, args, terminator.source_info.span);
+                    }
                     _ => {}
                 }
             }
@@ -132,9 +136,19 @@ fn resolve_rust_intrinsic(
 ) -> Option<(Symbol, SubstsRef<'tcx>)> {
     if let ty::FnDef(def_id, substs) = *func_ty.kind() {
         let fn_sig = func_ty.fn_sig(tcx);
-        if fn_sig.abi() == Abi::RustIntrinsic {
+        if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = fn_sig.abi() {
             return Some((tcx.item_name(def_id), substs));
         }
     }
     None
 }
+
+fn validate_simd_shuffle(tcx: TyCtxt<'tcx>, args: &[Operand<'tcx>], span: Span) {
+    match &args[2] {
+        Operand::Constant(_) => {} // all good
+        _ => {
+            let msg = format!("last argument of `simd_shuffle` is required to be a `const` item");
+            tcx.sess.span_err(span, &msg);
+        }
+    }
+}

compiler/rustc_mir/src/transform/promote_consts.rs

@@ -12,20 +12,16 @@
 //! initialization and can otherwise silence errors, if
 //! move analysis runs after promotion on broken MIR.
 
-use rustc_ast::LitKind;
 use rustc_hir as hir;
-use rustc_hir::def_id::DefId;
 use rustc_middle::mir::traversal::ReversePostorder;
 use rustc_middle::mir::visit::{MutVisitor, MutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
 use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{self, List, TyCtxt, TypeFoldable};
-use rustc_span::symbol::sym;
 use rustc_span::Span;
 
 use rustc_index::vec::{Idx, IndexVec};
-use rustc_target::spec::abi::Abi;
 
 use std::cell::Cell;
 use std::{cmp, iter, mem};
@@ -36,8 +32,8 @@ use crate::transform::MirPass;
 
 /// A `MirPass` for promotion.
 ///
-/// Promotion is the extraction of promotable temps into separate MIR bodies. This pass also emits
+/// Promotion is the extraction of promotable temps into separate MIR bodies so they can have
-/// errors when promotion of `#[rustc_args_required_const]` arguments fails.
+/// `'static` lifetime.
 ///
 /// After this pass is run, `promoted_fragments` will hold the MIR body corresponding to each
 /// newly created `Constant`.
@@ -101,47 +97,16 @@ impl TempState {
 pub enum Candidate {
     /// Borrow of a constant temporary, candidate for lifetime extension.
     Ref(Location),
-
-    /// Currently applied to function calls where the callee has the unstable
-    /// `#[rustc_args_required_const]` attribute as well as the SIMD shuffle
-    /// intrinsic. The intrinsic requires the arguments are indeed constant and
-    /// the attribute currently provides the semantic requirement that arguments
-    /// must be constant.
-    Argument { bb: BasicBlock, index: usize },
 }
 
 impl Candidate {
-    /// Returns `true` if we should use the "explicit" rules for promotability for this `Candidate`.
-    fn forces_explicit_promotion(&self) -> bool {
-        match self {
-            Candidate::Ref(_) => false,
-            Candidate::Argument { .. } => true,
-        }
-    }
-
     fn source_info(&self, body: &Body<'_>) -> SourceInfo {
         match self {
             Candidate::Ref(location) => *body.source_info(*location),
-            Candidate::Argument { bb, .. } => *body.source_info(body.terminator_loc(*bb)),
         }
     }
 }
 
-fn args_required_const(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Vec<usize>> {
-    let attrs = tcx.get_attrs(def_id);
-    let attr = attrs.iter().find(|a| tcx.sess.check_name(a, sym::rustc_args_required_const))?;
-    let mut ret = vec![];
-    for meta in attr.meta_item_list()? {
-        match meta.literal()?.kind {
-            LitKind::Int(a, _) => {
-                ret.push(a as usize);
-            }
-            _ => bug!("invalid arg index"),
-        }
-    }
-    Some(ret)
-}
-
 struct Collector<'a, 'tcx> {
     ccx: &'a ConstCx<'a, 'tcx>,
     temps: IndexVec<Local, TempState>,
@@ -208,31 +173,6 @@ impl<'tcx> Visitor<'tcx> for Collector<'_, 'tcx> {
             _ => {}
         }
     }
-
-    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
-        self.super_terminator(terminator, location);
-
-        if let TerminatorKind::Call { ref func, .. } = terminator.kind {
-            if let ty::FnDef(def_id, _) = *func.ty(self.ccx.body, self.ccx.tcx).kind() {
-                let fn_sig = self.ccx.tcx.fn_sig(def_id);
-                if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = fn_sig.abi() {
-                    let name = self.ccx.tcx.item_name(def_id);
-                    // FIXME(eddyb) use `#[rustc_args_required_const(2)]` for shuffles.
-                    if name.as_str().starts_with("simd_shuffle") {
-                        self.candidates.push(Candidate::Argument { bb: location.block, index: 2 });
-
-                        return; // Don't double count `simd_shuffle` candidates
-                    }
-                }
-
-                if let Some(constant_args) = args_required_const(self.ccx.tcx, def_id) {
-                    for index in constant_args {
-                        self.candidates.push(Candidate::Argument { bb: location.block, index });
-                    }
-                }
-            }
-        }
-    }
 }
 
 pub fn collect_temps_and_candidates(
@@ -256,14 +196,6 @@ pub fn collect_temps_and_candidates(
 struct Validator<'a, 'tcx> {
     ccx: &'a ConstCx<'a, 'tcx>,
     temps: &'a IndexVec<Local, TempState>,
-
-    /// Explicit promotion happens e.g. for constant arguments declared via
-    /// `rustc_args_required_const`.
-    /// Implicit promotion has almost the same rules, except that disallows `const fn`
-    /// except for those marked `#[rustc_promotable]`. This is to avoid changing
-    /// a legitimate run-time operation into a failing compile-time operation
-    /// e.g. due to addresses being compared inside the function.
-    explicit: bool,
 }
 
 impl std::ops::Deref for Validator<'a, 'tcx> {
@@ -280,8 +212,6 @@ impl<'tcx> Validator<'_, 'tcx> {
     fn validate_candidate(&self, candidate: Candidate) -> Result<(), Unpromotable> {
         match candidate {
             Candidate::Ref(loc) => {
-                assert!(!self.explicit);
-
                 let statement = &self.body[loc.block].statements[loc.statement_index];
                 match &statement.kind {
                     StatementKind::Assign(box (_, Rvalue::Ref(_, kind, place))) => {
@@ -310,15 +240,6 @@ impl<'tcx> Validator<'_, 'tcx> {
                     _ => bug!(),
                 }
             }
-            Candidate::Argument { bb, index } => {
-                assert!(self.explicit);
-
-                let terminator = self.body[bb].terminator();
-                match &terminator.kind {
-                    TerminatorKind::Call { args, .. } => self.validate_operand(&args[index]),
-                    _ => bug!(),
-                }
-            }
         }
     }
 
@@ -448,12 +369,10 @@ impl<'tcx> Validator<'_, 'tcx> {
                     ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {}
 
                     ProjectionElem::Index(local) => {
-                        if !self.explicit {
                         let mut promotable = false;
                         // Only accept if we can predict the index and are indexing an array.
-                            let val = if let TempState::Defined { location: loc, .. } =
+                        let val =
-                                self.temps[local]
+                            if let TempState::Defined { location: loc, .. } = self.temps[local] {
-                            {
                                 let block = &self.body[loc.block];
                                 if loc.statement_index < block.statements.len() {
                                     let statement = &block.statements[loc.statement_index];
@@ -476,8 +395,7 @@ impl<'tcx> Validator<'_, 'tcx> {
                             match ty.kind() {
                                 ty::Array(_, len) => {
                                     // It's an array; determine its length.
-                                        if let Some(len) =
+                                    if let Some(len) = len.try_eval_usize(self.tcx, self.param_env)
-                                            len.try_eval_usize(self.tcx, self.param_env)
                                     {
                                         // If the index is in-bounds, go ahead.
                                         if idx < len {
@@ -491,7 +409,7 @@ impl<'tcx> Validator<'_, 'tcx> {
                         if !promotable {
                             return Err(Unpromotable);
                         }
-                        }
+
                         self.validate_local(local)?;
                     }
 
@@ -636,7 +554,7 @@ impl<'tcx> Validator<'_, 'tcx> {
 
                 match op {
                     BinOp::Div | BinOp::Rem => {
-                        if !self.explicit && lhs_ty.is_integral() {
+                        if lhs_ty.is_integral() {
                             // Integer division: the RHS must be a non-zero const.
                             let const_val = match rhs {
                                 Operand::Constant(c) => {
@@ -721,10 +639,9 @@ impl<'tcx> Validator<'_, 'tcx> {
     ) -> Result<(), Unpromotable> {
         let fn_ty = callee.ty(self.body, self.tcx);
 
-        // When doing explicit promotion and inside const/static items, we promote all (eligible) function calls.
+        // Inside const/static items, we promote all (eligible) function calls.
         // Everywhere else, we require `#[rustc_promotable]` on the callee.
-        let promote_all_const_fn = self.explicit
+        let promote_all_const_fn = matches!(
-            || matches!(
             self.const_kind,
             Some(hir::ConstContext::Static(_) | hir::ConstContext::Const)
         );
@@ -765,41 +682,12 @@ pub fn validate_candidates(
     temps: &IndexVec<Local, TempState>,
     candidates: &[Candidate],
 ) -> Vec<Candidate> {
-    let mut validator = Validator { ccx, temps, explicit: false };
+    let validator = Validator { ccx, temps };
 
     candidates
         .iter()
         .copied()
-        .filter(|&candidate| {
+        .filter(|&candidate| validator.validate_candidate(candidate).is_ok())
-            validator.explicit = candidate.forces_explicit_promotion();
-
-            // FIXME(eddyb) also emit the errors for shuffle indices
-            // and `#[rustc_args_required_const]` arguments here.
-
-            let is_promotable = validator.validate_candidate(candidate).is_ok();
-
-            // If we use explicit validation, we carry the risk of turning a legitimate run-time
-            // operation into a failing compile-time operation. Make sure that does not happen
-            // by asserting that there is no possible run-time behavior here in case promotion
-            // fails.
-            if validator.explicit && !is_promotable {
-                ccx.tcx.sess.delay_span_bug(
-                    ccx.body.span,
-                    "Explicit promotion requested, but failed to promote",
-                );
-            }
-
-            match candidate {
-                Candidate::Argument { bb, index } if !is_promotable => {
-                    let span = ccx.body[bb].terminator().source_info.span;
-                    let msg = format!("argument {} is required to be a constant", index + 1);
-                    ccx.tcx.sess.span_err(span, &msg);
-                }
-                _ => (),
-            }
-
-            is_promotable
-        })
         .collect()
 }
 
@@ -1039,26 +927,6 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                         _ => bug!(),
                     }
                 }
-                Candidate::Argument { bb, index } => {
-                    let terminator = blocks[bb].terminator_mut();
-                    match terminator.kind {
-                        TerminatorKind::Call { ref mut args, .. } => {
-                            let ty = args[index].ty(local_decls, self.tcx);
-                            let span = terminator.source_info.span;
-
-                            Rvalue::Use(mem::replace(&mut args[index], promoted_operand(ty, span)))
-                        }
-                        // We expected a `TerminatorKind::Call` for which we'd like to promote an
-                        // argument. `qualify_consts` saw a `TerminatorKind::Call` here, but
-                        // we are seeing a `Goto`. That means that the `promote_temps` method
-                        // already promoted this call away entirely. This case occurs when calling
-                        // a function requiring a constant argument and as that constant value
-                        // providing a value whose computation contains another call to a function
-                        // requiring a constant argument.
-                        TerminatorKind::Goto { .. } => return None,
-                        _ => bug!(),
-                    }
-                }
             }
         };
 
@@ -1113,7 +981,6 @@ pub fn promote_candidates<'tcx>(
                     }
                 }
             }
-            Candidate::Argument { .. } => {}
         }
 
         // Declare return place local so that `mir::Body::new` doesn't complain.

compiler/rustc_passes/src/check_attr.rs

@@ -13,9 +13,7 @@ use rustc_errors::{pluralize, struct_span_err, Applicability};
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc_hir::{
+use rustc_hir::{self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID};
-    self, FnSig, ForeignItem, ForeignItemKind, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID,
-};
 use rustc_hir::{MethodKind, Target};
 use rustc_session::lint::builtin::{
     CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
@@ -81,9 +79,6 @@ impl CheckAttrVisitor<'tcx> {
                 sym::doc => self.check_doc_attrs(attr, hir_id, target, &mut specified_inline),
                 sym::no_link => self.check_no_link(hir_id, &attr, span, target),
                 sym::export_name => self.check_export_name(hir_id, &attr, span, target),
-                sym::rustc_args_required_const => {
-                    self.check_rustc_args_required_const(&attr, span, target, item)
-                }
                 sym::rustc_layout_scalar_valid_range_start
                 | sym::rustc_layout_scalar_valid_range_end => {
                     self.check_rustc_layout_scalar_valid_range(&attr, span, target)
@@ -948,79 +943,6 @@ impl CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks if `#[rustc_args_required_const]` is applied to a function and has a valid argument.
-    fn check_rustc_args_required_const(
-        &self,
-        attr: &Attribute,
-        span: &Span,
-        target: Target,
-        item: Option<ItemLike<'_>>,
-    ) -> bool {
-        let is_function = matches!(target, Target::Fn | Target::Method(..) | Target::ForeignFn);
-        if !is_function {
-            self.tcx
-                .sess
-                .struct_span_err(attr.span, "attribute should be applied to a function")
-                .span_label(*span, "not a function")
-                .emit();
-            return false;
-        }
-
-        let list = match attr.meta_item_list() {
-            // The attribute form is validated on AST.
-            None => return false,
-            Some(it) => it,
-        };
-
-        let mut invalid_args = vec![];
-        for meta in list {
-            if let Some(LitKind::Int(val, _)) = meta.literal().map(|lit| &lit.kind) {
-                if let Some(ItemLike::Item(Item {
-                    kind: ItemKind::Fn(FnSig { decl, .. }, ..),
-                    ..
-                }))
-                | Some(ItemLike::ForeignItem(ForeignItem {
-                    kind: ForeignItemKind::Fn(decl, ..),
-                    ..
-                })) = item
-                {
-                    let arg_count = decl.inputs.len() as u128;
-                    if *val >= arg_count {
-                        let span = meta.span();
-                        self.tcx
-                            .sess
-                            .struct_span_err(span, "index exceeds number of arguments")
-                            .span_label(
-                                span,
-                                format!(
-                                    "there {} only {} argument{}",
-                                    if arg_count != 1 { "are" } else { "is" },
-                                    arg_count,
-                                    pluralize!(arg_count)
-                                ),
-                            )
-                            .emit();
-                        return false;
-                    }
-                } else {
-                    bug!("should be a function item");
-                }
-            } else {
-                invalid_args.push(meta.span());
-            }
-        }
-
-        if !invalid_args.is_empty() {
-            self.tcx
-                .sess
-                .struct_span_err(invalid_args, "arguments should be non-negative integers")
-                .emit();
-            false
-        } else {
-            true
-        }
-    }
-
     fn check_rustc_layout_scalar_valid_range(
         &self,
         attr: &Attribute,

compiler/rustc_span/src/symbol.rs

@@ -994,7 +994,6 @@ symbols! {
         rustc_allocator,
         rustc_allocator_nounwind,
         rustc_allow_const_fn_unstable,
-        rustc_args_required_const,
         rustc_attrs,
         rustc_builtin_macro,
         rustc_capture_analysis,

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1537,8 +1537,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         }
 
-        self.check_rustc_args_require_const(def_id, hir_id, span);
-
         debug!("instantiate_value_path: type of {:?} is {:?}", hir_id, ty_substituted);
         self.write_substs(hir_id, substs);
 

compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

@@ -18,7 +18,7 @@ use rustc_middle::ty::adjustment::AllowTwoPhase;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::Session;
-use rustc_span::symbol::{sym, Ident};
+use rustc_span::symbol::Ident;
 use rustc_span::{self, MultiSpan, Span};
 use rustc_trait_selection::traits::{self, ObligationCauseCode, StatementAsExpression};
 
@@ -720,34 +720,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ty
     }
 
-    pub(in super::super) fn check_rustc_args_require_const(
-        &self,
-        def_id: DefId,
-        hir_id: hir::HirId,
-        span: Span,
-    ) {
-        // We're only interested in functions tagged with
-        // #[rustc_args_required_const], so ignore anything that's not.
-        if !self.tcx.has_attr(def_id, sym::rustc_args_required_const) {
-            return;
-        }
-
-        // If our calling expression is indeed the function itself, we're good!
-        // If not, generate an error that this can only be called directly.
-        if let Node::Expr(expr) = self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)) {
-            if let ExprKind::Call(ref callee, ..) = expr.kind {
-                if callee.hir_id == hir_id {
-                    return;
-                }
-            }
-        }
-
-        self.tcx.sess.span_err(
-            span,
-            "this function can only be invoked directly, not through a function pointer",
-        );
-    }
-
     /// A common error is to add an extra semicolon:
     ///
     /// ```

library/stdarch

@@ -1 +1 @@
-Subproject commit 6c4f4e1990b76be8a07bde1956d2e3452fd55ee4
+Subproject commit c14e98417feb406df66e821ccd81e1293b4baa6f

src/test/incremental/issue-61530.rs

@@ -11,7 +11,8 @@ extern "platform-intrinsic" {
 
 fn main() {
     unsafe {
-        let _: I32x2 = simd_shuffle2(I32x2(1, 2), I32x2(3, 4), [0, 0]);
+        const IDX: [u32; 2] = [0, 0];
-        let _: I32x2 = simd_shuffle2(I32x2(1, 2), I32x2(3, 4), [0, 0]);
+        let _: I32x2 = simd_shuffle2(I32x2(1, 2), I32x2(3, 4), IDX);
+        let _: I32x2 = simd_shuffle2(I32x2(1, 2), I32x2(3, 4), IDX);
     }
 }

src/test/ui/consts/const-eval/double_promotion.rs

@@ -1,17 +0,0 @@
-// check-pass
-
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-pub const fn a(value: u8) -> u8 {
-    value
-}
-
-#[rustc_args_required_const(0)]
-pub fn b(_: u8) {
-    unimplemented!()
-}
-
-fn main() {
-    let _ = b(a(0));
-}

src/test/ui/consts/const_arg_local.rs

@@ -1,11 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-fn foo(_imm8: i32) {}
-
-fn bar() {
-    let imm8 = 3;
-    foo(imm8) //~ ERROR argument 1 is required to be a constant
-}
-
-fn main() {}

src/test/ui/consts/const_arg_local.stderr

@@ -1,8 +0,0 @@
-error: argument 1 is required to be a constant
-  --> $DIR/const_arg_local.rs:8:5
-   |
-LL |     foo(imm8)
-   |     ^^^^^^^^^
-
-error: aborting due to previous error
-

src/test/ui/consts/const_arg_promotable.rs

@@ -1,10 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-fn foo(_imm8: i32) {}
-
-fn bar() {
-    foo(*&mut 42) //~ ERROR argument 1 is required to be a constant
-}
-
-fn main() {}

src/test/ui/consts/const_arg_promotable.stderr

@@ -1,8 +0,0 @@
-error: argument 1 is required to be a constant
-  --> $DIR/const_arg_promotable.rs:7:5
-   |
-LL |     foo(*&mut 42)
-   |     ^^^^^^^^^^^^^
-
-error: aborting due to previous error
-

src/test/ui/consts/const_arg_promotable2.rs

@@ -1,18 +0,0 @@
-// This test is a regression test for a bug where we only checked function calls in no-const
-// functions for `rustc_args_required_const` arguments. This meant that even though `bar` needs its
-// argument to be const, inside a const fn (callable at runtime), the value for it may come from a
-// non-constant (namely an argument to the const fn).
-
-#![feature(rustc_attrs)]
-const fn foo(a: i32) {
-    bar(a); //~ ERROR argument 1 is required to be a constant
-}
-
-#[rustc_args_required_const(0)]
-const fn bar(_: i32) {}
-
-fn main() {
-    // this function call will pass a runtime-value (number of program arguments) to `foo`, which
-    // will in turn forward it to `bar`, which expects a compile-time argument
-    foo(std::env::args().count() as i32);
-}

src/test/ui/consts/const_arg_promotable2.stderr

@@ -1,8 +0,0 @@
-error: argument 1 is required to be a constant
-  --> $DIR/const_arg_promotable2.rs:8:5
-   |
-LL |     bar(a);
-   |     ^^^^^^
-
-error: aborting due to previous error
-

src/test/ui/consts/const_arg_wrapper.rs

@@ -1,10 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-fn foo(_imm8: i32) {}
-
-fn bar(imm8: i32) {
-    foo(imm8) //~ ERROR argument 1 is required to be a constant
-}
-
-fn main() {}

src/test/ui/consts/const_arg_wrapper.stderr

@@ -1,8 +0,0 @@
-error: argument 1 is required to be a constant
-  --> $DIR/const_arg_wrapper.rs:7:5
-   |
-LL |     foo(imm8)
-   |     ^^^^^^^^^
-
-error: aborting due to previous error
-

src/test/ui/consts/rustc-args-required-const.rs

@@ -1,27 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-fn foo(_a: i32) {
-}
-
-#[rustc_args_required_const(1)]
-fn bar(_a: i32, _b: i32) {
-}
-
-const A: i32 = 3;
-
-const fn baz() -> i32 {
-    3
-}
-
-fn main() {
-    foo(2);
-    foo(2 + 3);
-    const BAZ: i32 = baz();
-    foo(BAZ);
-    let a = 4;
-    foo(A);
-    foo(a); //~ ERROR: argument 1 is required to be a constant
-    bar(a, 3);
-    bar(a, a); //~ ERROR: argument 2 is required to be a constant
-}

src/test/ui/consts/rustc-args-required-const.stderr

@@ -1,14 +0,0 @@
-error: argument 1 is required to be a constant
-  --> $DIR/rustc-args-required-const.rs:24:5
-   |
-LL |     foo(a);
-   |     ^^^^^^
-
-error: argument 2 is required to be a constant
-  --> $DIR/rustc-args-required-const.rs:26:5
-   |
-LL |     bar(a, a);
-   |     ^^^^^^^^^
-
-error: aborting due to 2 previous errors
-

src/test/ui/invalid/invalid-rustc_args_required_const-arguments.rs

@@ -1,32 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)] //~ ERROR index exceeds number of arguments
-fn foo1() {}
-
-#[rustc_args_required_const(1)] //~ ERROR index exceeds number of arguments
-fn foo2(_: u8) {}
-
-#[rustc_args_required_const(a)] //~ ERROR arguments should be non-negative integers
-fn foo4() {}
-
-#[rustc_args_required_const(1, a, 2, b)] //~ ERROR arguments should be non-negative integers
-fn foo5(_: u8, _: u8, _: u8) {}
-
-#[rustc_args_required_const(0)] //~ ERROR attribute should be applied to a function
-struct S;
-
-#[rustc_args_required_const(0usize)] //~ ERROR suffixed literals are not allowed in attributes
-fn foo6(_: u8) {}
-
-extern {
-    #[rustc_args_required_const(1)] //~ ERROR index exceeds number of arguments
-    fn foo7(_: u8);
-}
-
-#[rustc_args_required_const] //~ ERROR malformed `rustc_args_required_const` attribute
-fn bar1() {}
-
-#[rustc_args_required_const = 1] //~ ERROR malformed `rustc_args_required_const` attribute
-fn bar2() {}
-
-fn main() {}

src/test/ui/invalid/invalid-rustc_args_required_const-arguments.stderr

@@ -1,60 +0,0 @@
-error: suffixed literals are not allowed in attributes
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:18:29
-   |
-LL | #[rustc_args_required_const(0usize)]
-   |                             ^^^^^^
-   |
-   = help: instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
-
-error: malformed `rustc_args_required_const` attribute input
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:26:1
-   |
-LL | #[rustc_args_required_const]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_args_required_const(N)]`
-
-error: malformed `rustc_args_required_const` attribute input
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:29:1
-   |
-LL | #[rustc_args_required_const = 1]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_args_required_const(N)]`
-
-error: index exceeds number of arguments
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:3:29
-   |
-LL | #[rustc_args_required_const(0)]
-   |                             ^ there are only 0 arguments
-
-error: index exceeds number of arguments
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:6:29
-   |
-LL | #[rustc_args_required_const(1)]
-   |                             ^ there is only 1 argument
-
-error: arguments should be non-negative integers
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:9:29
-   |
-LL | #[rustc_args_required_const(a)]
-   |                             ^
-
-error: arguments should be non-negative integers
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:12:32
-   |
-LL | #[rustc_args_required_const(1, a, 2, b)]
-   |                                ^     ^
-
-error: attribute should be applied to a function
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:15:1
-   |
-LL | #[rustc_args_required_const(0)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL | struct S;
-   | --------- not a function
-
-error: index exceeds number of arguments
-  --> $DIR/invalid-rustc_args_required_const-arguments.rs:22:33
-   |
-LL |     #[rustc_args_required_const(1)]
-   |                                 ^ there is only 1 argument
-
-error: aborting due to 9 previous errors
-

src/test/ui/issues/issue-38074.rs

@@ -1,20 +0,0 @@
-// run-pass
-// ignore-emscripten FIXME(#45351)
-
-#![feature(platform_intrinsics, repr_simd)]
-
-extern "platform-intrinsic" {
-    fn simd_shuffle2<T, U>(x: T, y: T, idx: [u32; 2]) -> U;
-}
-
-#[repr(simd)]
-#[derive(Clone, Copy)]
-#[allow(non_camel_case_types)]
-struct u64x2(u64, u64);
-
-fn main() {
-    let a = u64x2(1, 2);
-    let r: u64x2 = unsafe { simd_shuffle2(a, a, [0-0, 0-0]) };
-    assert_eq!(r.0, 1);
-    assert_eq!(r.1, 1);
-}

src/test/ui/rustc-args-required-const2.rs

@@ -1,10 +0,0 @@
-#![feature(rustc_attrs)]
-
-#[rustc_args_required_const(0)]
-fn foo(_a: i32) {
-}
-
-fn main() {
-    let a = foo; //~ ERROR: this function can only be invoked directly
-    a(2);
-}

src/test/ui/rustc-args-required-const2.stderr

@@ -1,8 +0,0 @@
-error: this function can only be invoked directly, not through a function pointer
-  --> $DIR/rustc-args-required-const2.rs:8:13
-   |
-LL |     let a = foo;
-   |             ^^^
-
-error: aborting due to previous error
-

src/test/ui/simd-intrinsic/simd-intrinsic-generic-elements.rs

@@ -50,25 +50,28 @@ fn main() {
         simd_extract::<_, f32>(x, 0);
         //~^ ERROR expected return type `i32` (element of input `i32x4`), found `f32`
 
-        simd_shuffle2::<i32, i32>(0, 0, [0; 2]);
+        const IDX2: [u32; 2] = [0; 2];
+        simd_shuffle2::<i32, i32>(0, 0, IDX2);
         //~^ ERROR expected SIMD input type, found non-SIMD `i32`
-        simd_shuffle4::<i32, i32>(0, 0, [0; 4]);
+        const IDX4: [u32; 4] = [0; 4];
+        simd_shuffle4::<i32, i32>(0, 0, IDX4);
         //~^ ERROR expected SIMD input type, found non-SIMD `i32`
-        simd_shuffle8::<i32, i32>(0, 0, [0; 8]);
+        const IDX8: [u32; 8] = [0; 8];
+        simd_shuffle8::<i32, i32>(0, 0, IDX8);
         //~^ ERROR expected SIMD input type, found non-SIMD `i32`
 
-        simd_shuffle2::<_, f32x2>(x, x, [0; 2]);
+        simd_shuffle2::<_, f32x2>(x, x, IDX2);
 //~^ ERROR element type `i32` (element of input `i32x4`), found `f32x2` with element type `f32`
-        simd_shuffle4::<_, f32x4>(x, x, [0; 4]);
+        simd_shuffle4::<_, f32x4>(x, x, IDX4);
 //~^ ERROR element type `i32` (element of input `i32x4`), found `f32x4` with element type `f32`
-        simd_shuffle8::<_, f32x8>(x, x, [0; 8]);
+        simd_shuffle8::<_, f32x8>(x, x, IDX8);
 //~^ ERROR element type `i32` (element of input `i32x4`), found `f32x8` with element type `f32`
 
-        simd_shuffle2::<_, i32x8>(x, x, [0; 2]);
+        simd_shuffle2::<_, i32x8>(x, x, IDX2);
         //~^ ERROR expected return type of length 2, found `i32x8` with length 8
-        simd_shuffle4::<_, i32x8>(x, x, [0; 4]);
+        simd_shuffle4::<_, i32x8>(x, x, IDX4);
         //~^ ERROR expected return type of length 4, found `i32x8` with length 8
-        simd_shuffle8::<_, i32x2>(x, x, [0; 8]);
+        simd_shuffle8::<_, i32x2>(x, x, IDX8);
         //~^ ERROR expected return type of length 8, found `i32x2` with length 2
     }
 }

src/test/ui/simd-intrinsic/simd-intrinsic-generic-elements.stderr

@@ -17,58 +17,58 @@ LL |         simd_extract::<_, f32>(x, 0);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:53:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:54:9
    |
-LL |         simd_shuffle2::<i32, i32>(0, 0, [0; 2]);
+LL |         simd_shuffle2::<i32, i32>(0, 0, IDX2);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected SIMD input type, found non-SIMD `i32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:55:9
-   |
-LL |         simd_shuffle4::<i32, i32>(0, 0, [0; 4]);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected SIMD input type, found non-SIMD `i32`
   --> $DIR/simd-intrinsic-generic-elements.rs:57:9
    |
-LL |         simd_shuffle8::<i32, i32>(0, 0, [0; 8]);
+LL |         simd_shuffle4::<i32, i32>(0, 0, IDX4);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x2` with element type `f32`
+error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected SIMD input type, found non-SIMD `i32`
   --> $DIR/simd-intrinsic-generic-elements.rs:60:9
    |
-LL |         simd_shuffle2::<_, f32x2>(x, x, [0; 2]);
+LL |         simd_shuffle8::<i32, i32>(0, 0, IDX8);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x2` with element type `f32`
+  --> $DIR/simd-intrinsic-generic-elements.rs:63:9
+   |
+LL |         simd_shuffle2::<_, f32x2>(x, x, IDX2);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x4` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:62:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:65:9
    |
-LL |         simd_shuffle4::<_, f32x4>(x, x, [0; 4]);
+LL |         simd_shuffle4::<_, f32x4>(x, x, IDX4);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected return element type `i32` (element of input `i32x4`), found `f32x8` with element type `f32`
-  --> $DIR/simd-intrinsic-generic-elements.rs:64:9
-   |
-LL |         simd_shuffle8::<_, f32x8>(x, x, [0; 8]);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return type of length 2, found `i32x8` with length 8
   --> $DIR/simd-intrinsic-generic-elements.rs:67:9
    |
-LL |         simd_shuffle2::<_, i32x8>(x, x, [0; 2]);
+LL |         simd_shuffle8::<_, f32x8>(x, x, IDX8);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0511]: invalid monomorphization of `simd_shuffle2` intrinsic: expected return type of length 2, found `i32x8` with length 8
+  --> $DIR/simd-intrinsic-generic-elements.rs:70:9
+   |
+LL |         simd_shuffle2::<_, i32x8>(x, x, IDX2);
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle4` intrinsic: expected return type of length 4, found `i32x8` with length 8
-  --> $DIR/simd-intrinsic-generic-elements.rs:69:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:72:9
    |
-LL |         simd_shuffle4::<_, i32x8>(x, x, [0; 4]);
+LL |         simd_shuffle4::<_, i32x8>(x, x, IDX4);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0511]: invalid monomorphization of `simd_shuffle8` intrinsic: expected return type of length 8, found `i32x2` with length 2
-  --> $DIR/simd-intrinsic-generic-elements.rs:71:9
+  --> $DIR/simd-intrinsic-generic-elements.rs:74:9
    |
-LL |         simd_shuffle8::<_, i32x2>(x, x, [0; 8]);
+LL |         simd_shuffle8::<_, i32x2>(x, x, IDX8);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 12 previous errors
 

src/test/ui/simd-intrinsic/simd-intrinsic-inlining-issue67557-ice.rs

@@ -21,5 +21,6 @@ fn main() {
 
 #[inline(always)]
 unsafe fn inline_me() -> Simd2 {
-    simd_shuffle2(Simd2(10, 11), Simd2(12, 13), [0, 3])
+    const IDX: [u32; 2] = [0, 3];
+    simd_shuffle2(Simd2(10, 11), Simd2(12, 13), IDX)
 }

src/test/ui/simd-intrinsic/simd-intrinsic-inlining-issue67557.rs

@@ -15,7 +15,8 @@ struct Simd2(u8, u8);
 
 fn main() {
     unsafe {
-        let p_res: Simd2 = simd_shuffle2(Simd2(10, 11), Simd2(12, 13), [0, 1]);
+        const IDX: [u32; 2] = [0, 1];
+        let p_res: Simd2 = simd_shuffle2(Simd2(10, 11), Simd2(12, 13), IDX);
         let a_res: Simd2 = inline_me();
 
         assert_10_11(p_res);
@@ -36,5 +37,6 @@ fn assert_10_13(x: Simd2) {
 
 #[inline(always)]
 unsafe fn inline_me() -> Simd2 {
-    simd_shuffle2(Simd2(10, 11), Simd2(12, 13), [0, 3])
+    const IDX: [u32; 2] = [0, 3];
+    simd_shuffle2(Simd2(10, 11), Simd2(12, 13), IDX)
 }

src/test/ui/simd/simd-intrinsic-generic-elements.rs

@@ -2,6 +2,8 @@
 // ignore-emscripten FIXME(#45351) hits an LLVM assert
 
 #![feature(repr_simd, platform_intrinsics)]
+#![allow(incomplete_features)]
+#![feature(inline_const)]
 
 #[repr(simd)]
 #[derive(Copy, Clone, Debug, PartialEq)]
@@ -82,19 +84,19 @@ fn main() {
     let y4 = i32x4(140, 141, 142, 143);
     let y8 = i32x8(180, 181, 182, 183, 184, 185, 186, 187);
     unsafe {
-        all_eq!(simd_shuffle2(x2, y2, [3, 0]), i32x2(121, 20));
+        all_eq!(simd_shuffle2(x2, y2, const { [3u32, 0] }), i32x2(121, 20));
-        all_eq!(simd_shuffle4(x2, y2, [3, 0, 1, 2]), i32x4(121, 20, 21, 120));
+        all_eq!(simd_shuffle4(x2, y2, const { [3u32, 0, 1, 2] }), i32x4(121, 20, 21, 120));
-        all_eq!(simd_shuffle8(x2, y2, [3, 0, 1, 2, 1, 2, 3, 0]),
+        all_eq!(simd_shuffle8(x2, y2, const { [3u32, 0, 1, 2, 1, 2, 3, 0] }),
                 i32x8(121, 20, 21, 120, 21, 120, 121, 20));
 
-        all_eq!(simd_shuffle2(x4, y4, [7, 2]), i32x2(143, 42));
+        all_eq!(simd_shuffle2(x4, y4, const { [7u32, 2] }), i32x2(143, 42));
-        all_eq!(simd_shuffle4(x4, y4, [7, 2, 5, 0]), i32x4(143, 42, 141, 40));
+        all_eq!(simd_shuffle4(x4, y4, const { [7u32, 2, 5, 0] }), i32x4(143, 42, 141, 40));
-        all_eq!(simd_shuffle8(x4, y4, [7, 2, 5, 0, 3, 6, 4, 1]),
+        all_eq!(simd_shuffle8(x4, y4, const { [7u32, 2, 5, 0, 3, 6, 4, 1] }),
                 i32x8(143, 42, 141, 40, 43, 142, 140, 41));
 
-        all_eq!(simd_shuffle2(x8, y8, [11, 5]), i32x2(183, 85));
+        all_eq!(simd_shuffle2(x8, y8, const { [11u32, 5] }), i32x2(183, 85));
-        all_eq!(simd_shuffle4(x8, y8, [11, 5, 15, 0]), i32x4(183, 85, 187, 80));
+        all_eq!(simd_shuffle4(x8, y8, const { [11u32, 5, 15, 0] }), i32x4(183, 85, 187, 80));
-        all_eq!(simd_shuffle8(x8, y8, [11, 5, 15, 0, 3, 8, 12, 1]),
+        all_eq!(simd_shuffle8(x8, y8, const { [11u32, 5, 15, 0, 3, 8, 12, 1] }),
                 i32x8(183, 85, 187, 80, 83, 180, 184, 81));
     }