Rollup merge of #137686 - nbdd0121:asm_const, r=compiler-errors

Handle asm const similar to inline const

Previously, asm consts are handled similar to anon consts rather than inline consts. Anon consts are not good at dealing with lifetimes, because `type_of` has lifetimes erased already. Inline consts can deal with lifetimes because they live in an outer typeck context. And since `global_asm!` lacks an outer typeck context, we have implemented asm consts with anon consts while they're in fact more similar to inline consts.

This was changed in #137180, and this means that handling asm consts as inline consts are possible. While as `@compiler-errors` pointed out, `const` currently can't be used with any types with lifetime, this is about to change if #128464 is implemented. This PR is a preparatory PR for that feature.

As an unintentional side effect, fix #117877.

cc `@Amanieu`
r? `@compiler-errors`

Author: matthiaskrgr

Diff for: compiler/rustc_ast_lowering/src/asm.rs

@@ -195,7 +195,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                     }
                     InlineAsmOperand::Const { anon_const } => hir::InlineAsmOperand::Const {
-                        anon_const: self.lower_anon_const_to_anon_const(anon_const),
+                        anon_const: self.lower_const_block(anon_const),
                     },
                     InlineAsmOperand::Sym { sym } => {
                         let static_def_id = self

Diff for: compiler/rustc_hir/src/hir.rs

@@ -3512,7 +3512,7 @@ pub enum InlineAsmOperand<'hir> {
         out_expr: Option<&'hir Expr<'hir>>,
     },
     Const {
-        anon_const: &'hir AnonConst,
+        anon_const: ConstBlock,
     },
     SymFn {
         expr: &'hir Expr<'hir>,

Diff for: compiler/rustc_hir/src/intravisit.rs

@@ -1447,7 +1447,7 @@ pub fn walk_inline_asm<'v, V: Visitor<'v>>(
                 visit_opt!(visitor, visit_expr, out_expr);
             }
             InlineAsmOperand::Const { anon_const, .. } => {
-                try_visit!(visitor.visit_anon_const(anon_const));
+                try_visit!(visitor.visit_inline_const(anon_const));
             }
             InlineAsmOperand::SymFn { expr, .. } => {
                 try_visit!(visitor.visit_expr(expr));

Diff for: compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -1,5 +1,3 @@
-use std::assert_matches::debug_assert_matches;
-
 use rustc_abi::FieldIdx;
 use rustc_ast::InlineAsmTemplatePiece;
 use rustc_data_structures::fx::FxIndexSet;
@@ -21,6 +19,7 @@ pub struct InlineAsmCtxt<'a, 'tcx: 'a> {
     typing_env: ty::TypingEnv<'tcx>,
     target_features: &'tcx FxIndexSet<Symbol>,
     expr_ty: Box<dyn Fn(&hir::Expr<'tcx>) -> Ty<'tcx> + 'a>,
+    node_ty: Box<dyn Fn(hir::HirId) -> Ty<'tcx> + 'a>,
 }
 
 enum NonAsmTypeReason<'tcx> {
@@ -35,20 +34,26 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
         tcx: TyCtxt<'tcx>,
         def_id: LocalDefId,
         typing_env: ty::TypingEnv<'tcx>,
-        get_operand_ty: impl Fn(&hir::Expr<'tcx>) -> Ty<'tcx> + 'a,
+        expr_ty: impl Fn(&hir::Expr<'tcx>) -> Ty<'tcx> + 'a,
+        node_ty: impl Fn(hir::HirId) -> Ty<'tcx> + 'a,
     ) -> Self {
         InlineAsmCtxt {
             tcx,
             typing_env,
             target_features: tcx.asm_target_features(def_id),
-            expr_ty: Box::new(get_operand_ty),
+            expr_ty: Box::new(expr_ty),
+            node_ty: Box::new(node_ty),
         }
     }
 
     fn expr_ty(&self, expr: &hir::Expr<'tcx>) -> Ty<'tcx> {
         (self.expr_ty)(expr)
     }
 
+    fn node_ty(&self, hir_id: hir::HirId) -> Ty<'tcx> {
+        (self.node_ty)(hir_id)
+    }
+
     // FIXME(compiler-errors): This could use `<$ty as Pointee>::Metadata == ()`
     fn is_thin_ptr_ty(&self, ty: Ty<'tcx>) -> bool {
         // Type still may have region variables, but `Sized` does not depend
@@ -487,12 +492,23 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
                         );
                     }
                 }
-                // Typeck has checked that Const operands are integers.
                 hir::InlineAsmOperand::Const { anon_const } => {
-                    debug_assert_matches!(
-                        self.tcx.type_of(anon_const.def_id).instantiate_identity().kind(),
-                        ty::Error(_) | ty::Int(_) | ty::Uint(_)
-                    );
+                    let ty = self.node_ty(anon_const.hir_id);
+                    match ty.kind() {
+                        ty::Error(_) => {}
+                        _ if ty.is_integral() => {}
+                        _ => {
+                            self.tcx
+                                .dcx()
+                                .struct_span_err(op_sp, "invalid type for `const` operand")
+                                .with_span_label(
+                                    self.tcx.def_span(anon_const.def_id),
+                                    format!("is {} `{}`", ty.kind().article(), ty),
+                                )
+                                .with_help("`const` operands must be of an integer type")
+                                .emit();
+                        }
+                    }
                 }
                 // Typeck has checked that SymFn refers to a function.
                 hir::InlineAsmOperand::SymFn { expr } => {

Diff for: compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -186,17 +186,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                     {
                         Some(parent_did)
                     }
-                    // Exclude `GlobalAsm` here which cannot have generics.
-                    Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
-                        if asm.operands.iter().any(|(op, _op_sp)| match op {
-                            hir::InlineAsmOperand::Const { anon_const } => {
-                                anon_const.hir_id == hir_id
-                            }
-                            _ => false,
-                        }) =>
-                    {
-                        Some(parent_did)
-                    }
                     Node::TyPat(_) => Some(parent_did),
                     _ => None,
                 }

Diff for: compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -8,7 +8,7 @@ use rustc_middle::query::plumbing::CyclePlaceholder;
 use rustc_middle::ty::fold::fold_regions;
 use rustc_middle::ty::print::with_forced_trimmed_paths;
 use rustc_middle::ty::util::IntTypeExt;
-use rustc_middle::ty::{self, Article, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{DUMMY_SP, Ident, Span};
 
@@ -35,13 +35,6 @@ fn anon_const_type_of<'tcx>(icx: &ItemCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx
     let parent_node_id = tcx.parent_hir_id(hir_id);
     let parent_node = tcx.hir_node(parent_node_id);
 
-    let find_const = |&(op, op_sp)| match op {
-        hir::InlineAsmOperand::Const { anon_const } if anon_const.hir_id == hir_id => {
-            Some((anon_const, op_sp))
-        }
-        _ => None,
-    };
-
     match parent_node {
         // Anon consts "inside" the type system.
         Node::ConstArg(&ConstArg {
@@ -50,31 +43,6 @@ fn anon_const_type_of<'tcx>(icx: &ItemCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx
             ..
         }) if anon_hir_id == hir_id => const_arg_anon_type_of(icx, arg_hir_id, span),
 
-        // Anon consts outside the type system.
-        Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
-        | Node::Item(&Item { kind: ItemKind::GlobalAsm { asm, .. }, .. })
-            if let Some((anon_const, op_sp)) = asm.operands.iter().find_map(find_const) =>
-        {
-            let ty = tcx.typeck(def_id).node_type(hir_id);
-
-            match ty.kind() {
-                ty::Error(_) => ty,
-                ty::Int(_) | ty::Uint(_) => ty,
-                _ => {
-                    let guar = tcx
-                        .dcx()
-                        .struct_span_err(op_sp, "invalid type for `const` operand")
-                        .with_span_label(
-                            tcx.def_span(anon_const.def_id),
-                            format!("is {} `{}`", ty.kind().article(), ty),
-                        )
-                        .with_help("`const` operands must be of an integer type")
-                        .emit();
-
-                    Ty::new_error(tcx, guar)
-                }
-            }
-        }
         Node::Variant(Variant { disr_expr: Some(e), .. }) if e.hir_id == hir_id => {
             tcx.adt_def(tcx.hir_get_parent_item(hir_id)).repr().discr_type().to_ty(tcx)
         }

Diff for: compiler/rustc_hir_pretty/src/lib.rs

@@ -1413,7 +1413,8 @@ impl<'a> State<'a> {
                 hir::InlineAsmOperand::Const { ref anon_const } => {
                     s.word("const");
                     s.space();
-                    s.print_anon_const(anon_const);
+                    // Not using `print_inline_const` to avoid additional `const { ... }`
+                    s.ann.nested(s, Nested::Body(anon_const.body))
                 }
                 hir::InlineAsmOperand::SymFn { ref expr } => {
                     s.word("sym_fn");

Diff for: compiler/rustc_hir_typeck/src/expr.rs

@@ -3774,13 +3774,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         self.check_expr_asm_operand(out_expr, false);
                     }
                 }
+                hir::InlineAsmOperand::Const { ref anon_const } => {
+                    self.check_expr_const_block(anon_const, Expectation::NoExpectation);
+                }
                 hir::InlineAsmOperand::SymFn { expr } => {
                     self.check_expr(expr);
                 }
-                // `AnonConst`s have their own body and is type-checked separately.
-                // As they don't flow into the type system we don't need them to
-                // be well-formed.
-                hir::InlineAsmOperand::Const { .. } => {}
                 hir::InlineAsmOperand::SymStatic { .. } => {}
                 hir::InlineAsmOperand::Label { block } => {
                     let previous_diverges = self.diverges.get();

Diff for: compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -110,8 +110,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     self.tcx.erase_regions(ty)
                 }
             };
-            InlineAsmCtxt::new(self.tcx, enclosing_id, self.typing_env(self.param_env), expr_ty)
-                .check_asm(asm);
+            let node_ty = |hir_id: HirId| self.typeck_results.borrow().node_type(hir_id);
+            InlineAsmCtxt::new(
+                self.tcx,
+                enclosing_id,
+                self.typing_env(self.param_env),
+                expr_ty,
+                node_ty,
+            )
+            .check_asm(asm);
         }
     }
 

Diff for: compiler/rustc_hir_typeck/src/writeback.rs

@@ -248,13 +248,6 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
             }
         }
     }
-
-    fn visit_const_block(&mut self, span: Span, anon_const: &hir::ConstBlock) {
-        self.visit_node_id(span, anon_const.hir_id);
-
-        let body = self.tcx().hir_body(anon_const.body);
-        self.visit_body(body);
-    }
 }
 
 ///////////////////////////////////////////////////////////////////////////
@@ -284,9 +277,6 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
             hir::ExprKind::Field(..) | hir::ExprKind::OffsetOf(..) => {
                 self.visit_field_id(e.hir_id);
             }
-            hir::ExprKind::ConstBlock(ref anon_const) => {
-                self.visit_const_block(e.span, anon_const);
-            }
             _ => {}
         }
 
@@ -297,6 +287,14 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
         self.fix_index_builtin_expr(e);
     }
 
+    fn visit_inline_const(&mut self, anon_const: &hir::ConstBlock) {
+        let span = self.tcx().def_span(anon_const.def_id);
+        self.visit_node_id(span, anon_const.hir_id);
+
+        let body = self.tcx().hir_body(anon_const.body);
+        self.visit_body(body);
+    }
+
     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
         match &p.kind {
             hir::GenericParamKind::Lifetime { .. } => {
@@ -340,9 +338,6 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
 
     fn visit_pat_expr(&mut self, expr: &'tcx hir::PatExpr<'tcx>) {
         self.visit_node_id(expr.span, expr.hir_id);
-        if let hir::PatExprKind::ConstBlock(c) = &expr.kind {
-            self.visit_const_block(expr.span, c);
-        }
         intravisit::walk_pat_expr(self, expr);
     }
 

Diff for: compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -730,12 +730,20 @@ impl<'tcx> ThirBuildCx<'tcx> {
                             }
                         }
                         hir::InlineAsmOperand::Const { ref anon_const } => {
-                            let value =
-                                mir::Const::from_unevaluated(tcx, anon_const.def_id.to_def_id())
-                                    .instantiate_identity();
-                            let span = tcx.def_span(anon_const.def_id);
-
-                            InlineAsmOperand::Const { value, span }
+                            let ty = self.typeck_results.node_type(anon_const.hir_id);
+                            let did = anon_const.def_id.to_def_id();
+                            let typeck_root_def_id = tcx.typeck_root_def_id(did);
+                            let parent_args = tcx.erase_regions(GenericArgs::identity_for_item(
+                                tcx,
+                                typeck_root_def_id,
+                            ));
+                            let args =
+                                InlineConstArgs::new(tcx, InlineConstArgsParts { parent_args, ty })
+                                    .args;
+
+                            let uneval = mir::UnevaluatedConst::new(did, args);
+                            let value = mir::Const::Unevaluated(uneval, ty);
+                            InlineAsmOperand::Const { value, span: tcx.def_span(did) }
                         }
                         hir::InlineAsmOperand::SymFn { expr } => {
                             InlineAsmOperand::SymFn { value: self.mirror_expr(expr) }

Diff for: compiler/rustc_resolve/src/def_collector.rs

@@ -459,4 +459,43 @@ impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
         visit::walk_attribute(self, attr);
         self.in_attr = orig_in_attr;
     }
+
+    fn visit_inline_asm(&mut self, asm: &'a InlineAsm) {
+        let InlineAsm {
+            asm_macro: _,
+            template: _,
+            template_strs: _,
+            operands,
+            clobber_abis: _,
+            options: _,
+            line_spans: _,
+        } = asm;
+        for (op, _span) in operands {
+            match op {
+                InlineAsmOperand::In { expr, reg: _ }
+                | InlineAsmOperand::Out { expr: Some(expr), reg: _, late: _ }
+                | InlineAsmOperand::InOut { expr, reg: _, late: _ } => {
+                    self.visit_expr(expr);
+                }
+                InlineAsmOperand::Out { expr: None, reg: _, late: _ } => {}
+                InlineAsmOperand::SplitInOut { in_expr, out_expr, reg: _, late: _ } => {
+                    self.visit_expr(in_expr);
+                    if let Some(expr) = out_expr {
+                        self.visit_expr(expr);
+                    }
+                }
+                InlineAsmOperand::Const { anon_const } => {
+                    let def = self.create_def(
+                        anon_const.id,
+                        kw::Empty,
+                        DefKind::InlineConst,
+                        anon_const.value.span,
+                    );
+                    self.with_parent(def, |this| visit::walk_anon_const(this, anon_const));
+                }
+                InlineAsmOperand::Sym { sym } => self.visit_inline_asm_sym(sym),
+                InlineAsmOperand::Label { block } => self.visit_block(block),
+            }
+        }
+    }
 }

Diff for: tests/crashes/117877.rs

@@ -0,0 +1,10 @@
+//@ edition:2021
+//@ needs-asm-support
+
+use std::arch::asm;
+
+async unsafe fn foo<'a>() {
+    asm!("/* {0} */", const N); //~ ERROR E0425
+}
+
+fn main() {}

Diff for: tests/ui/asm/const-resolve-error.rs

@@ -0,0 +1,14 @@
+error[E0425]: cannot find value `N` in this scope
+  --> $DIR/const-resolve-error.rs:7:29
+   |
+LL |     asm!("/* {0} */", const N);
+   |                             ^ not found in this scope
+   |
+help: you might be missing a const parameter
+   |
+LL | async unsafe fn foo<'a, const N: /* Type */>() {
+   |                       +++++++++++++++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0425`.

Diff for: tests/ui/asm/const-resolve-error.stderr

@@ -5,6 +5,6 @@ use std::arch::global_asm;
 
 fn main() {}
 
-global_asm!("/* {} */", const 1 << 500); //~ ERROR evaluation of constant value failed [E0080]
+global_asm!("/* {} */", const 1 << 500); //~ ERROR E0080
 
-global_asm!("/* {} */", const 1 / 0); //~ ERROR evaluation of constant value failed [E0080]
+global_asm!("/* {} */", const 1 / 0); //~ ERROR E0080

Diff for: tests/ui/asm/fail-const-eval-issue-121099.rs

@@ -1,10 +1,10 @@
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `{global_asm#0}::{constant#0}` failed
   --> $DIR/fail-const-eval-issue-121099.rs:8:31
    |
 LL | global_asm!("/* {} */", const 1 << 500);
    |                               ^^^^^^^^ attempt to shift left by `500_i32`, which would overflow
 
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `{global_asm#1}::{constant#0}` failed
   --> $DIR/fail-const-eval-issue-121099.rs:10:31
    |
 LL | global_asm!("/* {} */", const 1 / 0);