Auto merge of rust-lang#83964 - Dylan-DPC:rollup-9kinaiv, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - rust-lang#83476 (Add strong_count mutation methods to Rc)
 - rust-lang#83634 (Do not emit the advanced diagnostics on macros)
 - rust-lang#83816 (Trigger `unused_doc_comments` on macros at once)
 - rust-lang#83916 (Use AnonConst for asm! constants)
 - rust-lang#83935 (forbid `impl Trait` in generic param defaults)
 - rust-lang#83936 (Disable using non-ascii identifiers in extern blocks.)
 - rust-lang#83945 (Add suggestion to reborrow mutable references when they're moved in a for loop)
 - rust-lang#83954 (Do not ICE when closure is involved in Trait Alias Impl Trait)

Failed merges:

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

compiler/rustc_ast/src/ast.rs

@@ -1998,7 +1998,7 @@ pub enum InlineAsmOperand {
         out_expr: Option<P<Expr>>,
     },
     Const {
-        expr: P<Expr>,
+        anon_const: AnonConst,
     },
     Sym {
         expr: P<Expr>,

compiler/rustc_ast/src/mut_visit.rs

@@ -1252,7 +1252,6 @@ pub fn noop_visit_expr<T: MutVisitor>(
                 match op {
                     InlineAsmOperand::In { expr, .. }
                     | InlineAsmOperand::InOut { expr, .. }
-                    | InlineAsmOperand::Const { expr, .. }
                     | InlineAsmOperand::Sym { expr, .. } => vis.visit_expr(expr),
                     InlineAsmOperand::Out { expr, .. } => {
                         if let Some(expr) = expr {
@@ -1265,6 +1264,7 @@ pub fn noop_visit_expr<T: MutVisitor>(
                             vis.visit_expr(out_expr);
                         }
                     }
+                    InlineAsmOperand::Const { anon_const, .. } => vis.visit_anon_const(anon_const),
                 }
             }
         }

compiler/rustc_ast/src/visit.rs

@@ -835,7 +835,6 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
                 match op {
                     InlineAsmOperand::In { expr, .. }
                     | InlineAsmOperand::InOut { expr, .. }
-                    | InlineAsmOperand::Const { expr, .. }
                     | InlineAsmOperand::Sym { expr, .. } => visitor.visit_expr(expr),
                     InlineAsmOperand::Out { expr, .. } => {
                         if let Some(expr) = expr {
@@ -848,6 +847,9 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) {
                             visitor.visit_expr(out_expr);
                         }
                     }
+                    InlineAsmOperand::Const { anon_const, .. } => {
+                        visitor.visit_anon_const(anon_const)
+                    }
                 }
             }
         }

compiler/rustc_ast_lowering/src/expr.rs

@@ -1411,9 +1411,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             out_expr: out_expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
                         }
                     }
-                    InlineAsmOperand::Const { ref expr } => {
-                        hir::InlineAsmOperand::Const { expr: self.lower_expr_mut(expr) }
-                    }
+                    InlineAsmOperand::Const { ref anon_const } => hir::InlineAsmOperand::Const {
+                        anon_const: self.lower_anon_const(anon_const),
+                    },
                     InlineAsmOperand::Sym { ref expr } => {
                         hir::InlineAsmOperand::Sym { expr: self.lower_expr_mut(expr) }
                     }

compiler/rustc_ast_lowering/src/lib.rs

@@ -2259,13 +2259,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 let kind = hir::GenericParamKind::Type {
                     default: default.as_ref().map(|x| {
-                        self.lower_ty(
-                            x,
-                            ImplTraitContext::OtherOpaqueTy {
-                                capturable_lifetimes: &mut FxHashSet::default(),
-                                origin: hir::OpaqueTyOrigin::Misc,
-                            },
-                        )
+                        self.lower_ty(x, ImplTraitContext::Disallowed(ImplTraitPosition::Other))
                     }),
                     synthetic: param
                         .attrs

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -532,6 +532,25 @@ impl<'a> AstValidator<'a> {
         }
     }
 
+    /// An item in `extern { ... }` cannot use non-ascii identifier.
+    fn check_foreign_item_ascii_only(&self, ident: Ident) {
+        let symbol_str = ident.as_str();
+        if !symbol_str.is_ascii() {
+            let n = 83942;
+            self.err_handler()
+                .struct_span_err(
+                    ident.span,
+                    "items in `extern` blocks cannot use non-ascii identifiers",
+                )
+                .span_label(self.current_extern_span(), "in this `extern` block")
+                .note(&format!(
+                    "This limitation may be lifted in the future; see issue #{} <https://github.com/rust-lang/rust/issues/{}> for more information",
+                    n, n,
+                ))
+                .emit();
+        }
+    }
+
     /// Reject C-varadic type unless the function is foreign,
     /// or free and `unsafe extern "C"` semantically.
     fn check_c_varadic_type(&self, fk: FnKind<'a>) {
@@ -592,7 +611,7 @@ impl<'a> AstValidator<'a> {
             self.session,
             ident.span,
             E0754,
-            "trying to load file for module `{}` with non ascii identifer name",
+            "trying to load file for module `{}` with non-ascii identifier name",
             ident.name
         )
         .help("consider using `#[path]` attribute to specify filesystem path")
@@ -1103,15 +1122,18 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 self.check_defaultness(fi.span, *def);
                 self.check_foreign_fn_bodyless(fi.ident, body.as_deref());
                 self.check_foreign_fn_headerless(fi.ident, fi.span, sig.header);
+                self.check_foreign_item_ascii_only(fi.ident);
             }
             ForeignItemKind::TyAlias(box TyAliasKind(def, generics, bounds, body)) => {
                 self.check_defaultness(fi.span, *def);
                 self.check_foreign_kind_bodyless(fi.ident, "type", body.as_ref().map(|b| b.span));
                 self.check_type_no_bounds(bounds, "`extern` blocks");
                 self.check_foreign_ty_genericless(generics);
+                self.check_foreign_item_ascii_only(fi.ident);
             }
             ForeignItemKind::Static(_, _, body) => {
                 self.check_foreign_kind_bodyless(fi.ident, "static", body.as_ref().map(|b| b.span));
+                self.check_foreign_item_ascii_only(fi.ident);
             }
             ForeignItemKind::MacCall(..) => {}
         }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -2149,10 +2149,10 @@ impl<'a> State<'a> {
                                     None => s.word("_"),
                                 }
                             }
-                            InlineAsmOperand::Const { expr } => {
+                            InlineAsmOperand::Const { anon_const } => {
                                 s.word("const");
                                 s.space();
-                                s.print_expr(expr);
+                                s.print_expr(&anon_const.value);
                             }
                             InlineAsmOperand::Sym { expr } => {
                                 s.word("sym");

compiler/rustc_builtin_macros/src/asm.rs

@@ -136,8 +136,8 @@ fn parse_args<'a>(
                 ast::InlineAsmOperand::InOut { reg, expr, late: true }
             }
         } else if p.eat_keyword(kw::Const) {
-            let expr = p.parse_expr()?;
-            ast::InlineAsmOperand::Const { expr }
+            let anon_const = p.parse_anon_const_expr()?;
+            ast::InlineAsmOperand::Const { anon_const }
         } else if p.eat_keyword(sym::sym) {
             let expr = p.parse_expr()?;
             match expr.kind {

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -822,41 +822,37 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     InlineAsmOperandRef::InOut { reg, late, in_value, out_place }
                 }
                 mir::InlineAsmOperand::Const { ref value } => {
-                    if let mir::Operand::Constant(constant) = value {
-                        let const_value = self
-                            .eval_mir_constant(constant)
-                            .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved"));
-                        let ty = constant.ty();
-                        let size = bx.layout_of(ty).size;
-                        let scalar = match const_value {
-                            ConstValue::Scalar(s) => s,
-                            _ => span_bug!(
-                                span,
-                                "expected Scalar for promoted asm const, but got {:#?}",
-                                const_value
-                            ),
-                        };
-                        let value = scalar.assert_bits(size);
-                        let string = match ty.kind() {
-                            ty::Uint(_) => value.to_string(),
-                            ty::Int(int_ty) => {
-                                match int_ty.normalize(bx.tcx().sess.target.pointer_width) {
-                                    ty::IntTy::I8 => (value as i8).to_string(),
-                                    ty::IntTy::I16 => (value as i16).to_string(),
-                                    ty::IntTy::I32 => (value as i32).to_string(),
-                                    ty::IntTy::I64 => (value as i64).to_string(),
-                                    ty::IntTy::I128 => (value as i128).to_string(),
-                                    ty::IntTy::Isize => unreachable!(),
-                                }
+                    let const_value = self
+                        .eval_mir_constant(value)
+                        .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved"));
+                    let ty = value.ty();
+                    let size = bx.layout_of(ty).size;
+                    let scalar = match const_value {
+                        ConstValue::Scalar(s) => s,
+                        _ => span_bug!(
+                            span,
+                            "expected Scalar for promoted asm const, but got {:#?}",
+                            const_value
+                        ),
+                    };
+                    let value = scalar.assert_bits(size);
+                    let string = match ty.kind() {
+                        ty::Uint(_) => value.to_string(),
+                        ty::Int(int_ty) => {
+                            match int_ty.normalize(bx.tcx().sess.target.pointer_width) {
+                                ty::IntTy::I8 => (value as i8).to_string(),
+                                ty::IntTy::I16 => (value as i16).to_string(),
+                                ty::IntTy::I32 => (value as i32).to_string(),
+                                ty::IntTy::I64 => (value as i64).to_string(),
+                                ty::IntTy::I128 => (value as i128).to_string(),
+                                ty::IntTy::Isize => unreachable!(),
                             }
-                            ty::Float(ty::FloatTy::F32) => f32::from_bits(value as u32).to_string(),
-                            ty::Float(ty::FloatTy::F64) => f64::from_bits(value as u64).to_string(),
-                            _ => span_bug!(span, "asm const has bad type {}", ty),
-                        };
-                        InlineAsmOperandRef::Const { string }
-                    } else {
-                        span_bug!(span, "asm const is not a constant");
-                    }
+                        }
+                        ty::Float(ty::FloatTy::F32) => f32::from_bits(value as u32).to_string(),
+                        ty::Float(ty::FloatTy::F64) => f64::from_bits(value as u64).to_string(),
+                        _ => span_bug!(span, "asm const has bad type {}", ty),
+                    };
+                    InlineAsmOperandRef::Const { string }
                 }
                 mir::InlineAsmOperand::SymFn { ref value } => {
                     let literal = self.monomorphize(value.literal);

compiler/rustc_expand/src/expand.rs

@@ -1067,13 +1067,23 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
     // since they will not be detected after macro expansion.
     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
         let features = self.cx.ecfg.features.unwrap();
-        for attr in attrs.iter() {
+        let mut attrs = attrs.iter().peekable();
+        let mut span: Option<Span> = None;
+        while let Some(attr) = attrs.next() {
             rustc_ast_passes::feature_gate::check_attribute(attr, self.cx.sess, features);
             validate_attr::check_meta(&self.cx.sess.parse_sess, attr);
+
+            let current_span = if let Some(sp) = span { sp.to(attr.span) } else { attr.span };
+            span = Some(current_span);
+
+            if attrs.peek().map_or(false, |next_attr| next_attr.doc_str().is_some()) {
+                continue;
+            }
+
             if attr.doc_str().is_some() {
                 self.cx.sess.parse_sess.buffer_lint_with_diagnostic(
                     &UNUSED_DOC_COMMENTS,
-                    attr.span,
+                    current_span,
                     ast::CRATE_NODE_ID,
                     "unused doc comment",
                     BuiltinLintDiagnostics::UnusedDocComment(attr.span),

compiler/rustc_hir/src/hir.rs

@@ -2347,7 +2347,7 @@ pub enum InlineAsmOperand<'hir> {
         out_expr: Option<Expr<'hir>>,
     },
     Const {
-        expr: Expr<'hir>,
+        anon_const: AnonConst,
     },
     Sym {
         expr: Expr<'hir>,

compiler/rustc_hir/src/intravisit.rs

@@ -1189,7 +1189,6 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
                 match op {
                     InlineAsmOperand::In { expr, .. }
                     | InlineAsmOperand::InOut { expr, .. }
-                    | InlineAsmOperand::Const { expr, .. }
                     | InlineAsmOperand::Sym { expr, .. } => visitor.visit_expr(expr),
                     InlineAsmOperand::Out { expr, .. } => {
                         if let Some(expr) = expr {
@@ -1202,6 +1201,9 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
                             visitor.visit_expr(out_expr);
                         }
                     }
+                    InlineAsmOperand::Const { anon_const, .. } => {
+                        visitor.visit_anon_const(anon_const)
+                    }
                 }
             }
         }

compiler/rustc_hir_pretty/src/lib.rs

@@ -1570,10 +1570,10 @@ impl<'a> State<'a> {
                                 None => s.word("_"),
                             }
                         }
-                        hir::InlineAsmOperand::Const { expr } => {
+                        hir::InlineAsmOperand::Const { anon_const } => {
                             s.word("const");
                             s.space();
-                            s.print_expr(expr);
+                            s.print_anon_const(anon_const);
                         }
                         hir::InlineAsmOperand::Sym { expr } => {
                             s.word("sym");

compiler/rustc_lint/src/builtin.rs

@@ -989,7 +989,7 @@ fn warn_if_doc(cx: &EarlyContext<'_>, node_span: Span, node_kind: &str, attrs: &
                 Some(sugared_span.map_or(attr.span, |span| span.with_hi(attr.span.hi())));
         }
 
-        if attrs.peek().map(|next_attr| next_attr.is_doc_comment()).unwrap_or_default() {
+        if attrs.peek().map_or(false, |next_attr| next_attr.is_doc_comment()) {
             continue;
         }
 

compiler/rustc_middle/src/mir/mod.rs

@@ -1213,7 +1213,7 @@ pub enum InlineAsmOperand<'tcx> {
         out_place: Option<Place<'tcx>>,
     },
     Const {
-        value: Operand<'tcx>,
+        value: Box<Constant<'tcx>>,
     },
     SymFn {
         value: Box<Constant<'tcx>>,

compiler/rustc_middle/src/mir/visit.rs

@@ -584,8 +584,7 @@ macro_rules! make_mir_visitor {
                     } => {
                         for op in operands {
                             match op {
-                                InlineAsmOperand::In { value, .. }
-                                | InlineAsmOperand::Const { value } => {
+                                InlineAsmOperand::In { value, .. } => {
                                     self.visit_operand(value, location);
                                 }
                                 InlineAsmOperand::Out { place, .. } => {
@@ -607,7 +606,8 @@ macro_rules! make_mir_visitor {
                                         );
                                     }
                                 }
-                                InlineAsmOperand::SymFn { value } => {
+                                InlineAsmOperand::Const { value }
+                                | InlineAsmOperand::SymFn { value } => {
                                     self.visit_constant(value, location);
                                 }
                                 InlineAsmOperand::SymStatic { def_id: _ } => {}

compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs

@@ -264,7 +264,24 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
                 if let Some(DesugaringKind::ForLoop(_)) = move_span.desugaring_kind() {
                     let sess = self.infcx.tcx.sess;
-                    if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) {
+                    let ty = used_place.ty(self.body, self.infcx.tcx).ty;
+                    // If we have a `&mut` ref, we need to reborrow.
+                    if let ty::Ref(_, _, hir::Mutability::Mut) = ty.kind() {
+                        // If we are in a loop this will be suggested later.
+                        if !is_loop_move {
+                            err.span_suggestion_verbose(
+                                move_span.shrink_to_lo(),
+                                &format!(
+                                    "consider creating a fresh reborrow of {} here",
+                                    self.describe_place(moved_place.as_ref())
+                                        .map(|n| format!("`{}`", n))
+                                        .unwrap_or_else(|| "the mutable reference".to_string()),
+                                ),
+                                format!("&mut *"),
+                                Applicability::MachineApplicable,
+                            );
+                        }
+                    } else if let Ok(snippet) = sess.source_map().span_to_snippet(move_span) {
                         err.span_suggestion(
                             move_span,
                             "consider borrowing to avoid moving into the for loop",

compiler/rustc_mir/src/borrow_check/invalidation.rs

@@ -204,8 +204,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
             } => {
                 for op in operands {
                     match *op {
-                        InlineAsmOperand::In { reg: _, ref value }
-                        | InlineAsmOperand::Const { ref value } => {
+                        InlineAsmOperand::In { reg: _, ref value } => {
                             self.consume_operand(location, value);
                         }
                         InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
@@ -219,7 +218,8 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
                                 self.mutate_place(location, out_place, Shallow(None), JustWrite);
                             }
                         }
-                        InlineAsmOperand::SymFn { value: _ }
+                        InlineAsmOperand::Const { value: _ }
+                        | InlineAsmOperand::SymFn { value: _ }
                         | InlineAsmOperand::SymStatic { def_id: _ } => {}
                     }
                 }

compiler/rustc_mir/src/borrow_check/mod.rs

@@ -734,8 +734,7 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
             } => {
                 for op in operands {
                     match *op {
-                        InlineAsmOperand::In { reg: _, ref value }
-                        | InlineAsmOperand::Const { ref value } => {
+                        InlineAsmOperand::In { reg: _, ref value } => {
                             self.consume_operand(loc, (value, span), flow_state);
                         }
                         InlineAsmOperand::Out { reg: _, late: _, place, .. } => {
@@ -761,7 +760,8 @@ impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tc
                                 );
                             }
                         }
-                        InlineAsmOperand::SymFn { value: _ }
+                        InlineAsmOperand::Const { value: _ }
+                        | InlineAsmOperand::SymFn { value: _ }
                         | InlineAsmOperand::SymStatic { def_id: _ } => {}
                     }
                 }