Rollup of 5 pull requests

compiler/rustc_ast_lowering/src/lib.rs

@@ -1269,9 +1269,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 }
                 GenericArg::Type(self.lower_ty_alloc(ty, itctx).try_as_ambig_ty().unwrap())
             }
-            ast::GenericArg::Const(ct) => GenericArg::Const(
-                self.lower_anon_const_to_const_arg_and_alloc(ct).try_as_ambig_ct().unwrap(),
-            ),
+            ast::GenericArg::Const(ct) => {
+                let ct = self.lower_anon_const_to_const_arg_and_alloc(ct);
+                match ct.try_as_ambig_ct() {
+                    Some(ct) => GenericArg::Const(ct),
+                    None => GenericArg::Infer(hir::InferArg { hir_id: ct.hir_id, span: ct.span }),
+                }
+            }
         }
     }
 

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -737,6 +737,23 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
             TokenTree::Token(token, spacing) => {
                 let token_str = self.token_to_string_ext(token, convert_dollar_crate);
                 self.word(token_str);
+                // Emit hygiene annotations for identity-bearing tokens,
+                // matching how print_ident() and print_lifetime() call ann_post().
+                match token.kind {
+                    token::Ident(name, _) => {
+                        self.ann_post(Ident::new(name, token.span));
+                    }
+                    token::NtIdent(ident, _) => {
+                        self.ann_post(ident);
+                    }
+                    token::Lifetime(name, _) => {
+                        self.ann_post(Ident::new(name, token.span));
+                    }
+                    token::NtLifetime(ident, _) => {
+                        self.ann_post(ident);
+                    }
+                    _ => {}
+                }
                 if let token::DocComment(..) = token.kind {
                     self.hardbreak()
                 }

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2874,6 +2874,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         span: Span,
     ) -> Const<'tcx> {
         let tcx = self.tcx();
+
+        let ty = if !ty.has_infer() { Some(ty) } else { None };
+
         if let LitKind::Err(guar) = *kind {
             return ty::Const::new_error(tcx, guar);
         }
@@ -2905,16 +2908,20 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         };
 
         let lit_input = match expr.kind {
-            hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: lit.node, ty, neg: false }),
+            hir::ExprKind::Lit(lit) => {
+                Some(LitToConstInput { lit: lit.node, ty: Some(ty), neg: false })
+            }
             hir::ExprKind::Unary(hir::UnOp::Neg, expr) => match expr.kind {
-                hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: lit.node, ty, neg: true }),
+                hir::ExprKind::Lit(lit) => {
+                    Some(LitToConstInput { lit: lit.node, ty: Some(ty), neg: true })
+                }
                 _ => None,
             },
             _ => None,
         };
 
         lit_input.and_then(|l| {
-            if const_lit_matches_ty(tcx, &l.lit, l.ty, l.neg) {
+            if const_lit_matches_ty(tcx, &l.lit, ty, l.neg) {
                 tcx.at(expr.span)
                     .lit_to_const(l)
                     .map(|value| ty::Const::new_value(tcx, value.valtree, value.ty))

compiler/rustc_lint/src/for_loops_over_fallibles.rs

@@ -49,6 +49,11 @@ impl<'tcx> LateLintPass<'tcx> for ForLoopsOverFallibles {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         let Some((pat, arg)) = extract_for_loop(expr) else { return };
 
+        // Do not put suggestions for external macros.
+        if pat.span.from_expansion() {
+            return;
+        }
+
         let arg_span = arg.span.source_callsite();
 
         let ty = cx.typeck_results().expr_ty(arg);
@@ -77,6 +82,8 @@ impl<'tcx> LateLintPass<'tcx> for ForLoopsOverFallibles {
         };
 
         let sub = if let Some(recv) = extract_iterator_next_call(cx, arg)
+            && recv.span.can_be_used_for_suggestions()
+            && recv.span.between(arg_span.shrink_to_hi()).can_be_used_for_suggestions()
             && let Ok(recv_snip) = cx.sess().source_map().span_to_snippet(recv.span)
         {
             ForLoopsOverFalliblesLoopSub::RemoveNext {

compiler/rustc_middle/src/ty/consts/lit.rs

@@ -10,7 +10,10 @@ pub struct LitToConstInput<'tcx> {
     /// The absolute value of the resultant constant.
     pub lit: LitKind,
     /// The type of the constant.
-    pub ty: Ty<'tcx>,
+    ///
+    /// `None` is used by const generics when the type of the constant is unknown, e.g.
+    /// if there are inference variables
+    pub ty: Option<Ty<'tcx>>,
     /// If the constant is negative.
     pub neg: bool,
 }

compiler/rustc_mir_build/src/builder/expr/as_constant.rs

@@ -50,7 +50,8 @@ pub(crate) fn as_constant_inner<'tcx>(
 
     match *kind {
         ExprKind::Literal { lit, neg } => {
-            let const_ = lit_to_mir_constant(tcx, LitToConstInput { lit: lit.node, ty, neg });
+            let const_ =
+                lit_to_mir_constant(tcx, LitToConstInput { lit: lit.node, ty: Some(ty), neg });
 
             ConstOperand { span, user_ty: None, const_ }
         }
@@ -109,6 +110,8 @@ pub(crate) fn as_constant_inner<'tcx>(
 fn lit_to_mir_constant<'tcx>(tcx: TyCtxt<'tcx>, lit_input: LitToConstInput<'tcx>) -> Const<'tcx> {
     let LitToConstInput { lit, ty, neg } = lit_input;
 
+    let ty = ty.expect("type of literal must be known at this point");
+
     if let Err(guar) = ty.error_reported() {
         return Const::Ty(Ty::new_error(tcx, guar), ty::Const::new_error(tcx, guar));
     }

compiler/rustc_mir_build/src/thir/constant.rs

@@ -31,25 +31,27 @@ pub(crate) fn lit_to_const<'tcx>(
             .unwrap_or_else(|| bug!("expected to create ScalarInt from uint {:?}", result))
     };
 
-    let (valtree, valtree_ty) = match (lit, expected_ty.kind()) {
+    let (valtree, valtree_ty) = match (lit, expected_ty.map(|ty| ty.kind())) {
         (ast::LitKind::Str(s, _), _) => {
             let str_bytes = s.as_str().as_bytes();
             let valtree_ty = Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, tcx.types.str_);
             (ty::ValTree::from_raw_bytes(tcx, str_bytes), valtree_ty)
         }
-        (ast::LitKind::ByteStr(byte_sym, _), ty::Ref(_, inner_ty, _))
+        (ast::LitKind::ByteStr(byte_sym, _), Some(ty::Ref(_, inner_ty, _)))
             if let ty::Slice(ty) | ty::Array(ty, _) = inner_ty.kind()
                 && let ty::Uint(UintTy::U8) = ty.kind() =>
         {
-            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty)
+            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty.unwrap())
         }
-        (ast::LitKind::ByteStr(byte_sym, _), ty::Slice(inner_ty) | ty::Array(inner_ty, _))
-            if tcx.features().deref_patterns()
-                && let ty::Uint(UintTy::U8) = inner_ty.kind() =>
+        (
+            ast::LitKind::ByteStr(byte_sym, _),
+            Some(ty::Slice(inner_ty) | ty::Array(inner_ty, _)),
+        ) if tcx.features().deref_patterns()
+            && let ty::Uint(UintTy::U8) = inner_ty.kind() =>
         {
             // Byte string literal patterns may have type `[u8]` or `[u8; N]` if `deref_patterns` is
             // enabled, in order to allow, e.g., `deref!(b"..."): Vec<u8>`.
-            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty)
+            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty.unwrap())
         }
         (ast::LitKind::ByteStr(byte_sym, _), _) => {
             let valtree = ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str());
@@ -79,11 +81,11 @@ pub(crate) fn lit_to_const<'tcx>(
                 trunc(if neg { u128::wrapping_neg(n.get()) } else { n.get() }, i.to_unsigned());
             (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_int(tcx, i))
         }
-        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), ty::Uint(ui)) if !neg => {
+        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), Some(ty::Uint(ui))) if !neg => {
             let scalar_int = trunc(n.get(), *ui);
             (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_uint(tcx, *ui))
         }
-        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), ty::Int(i)) => {
+        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), Some(ty::Int(i))) => {
             // Unsigned "negation" has the same bitwise effect as signed negation,
             // which gets the result we want without additional casts.
             let scalar_int =
@@ -101,7 +103,7 @@ pub(crate) fn lit_to_const<'tcx>(
             let bits = parse_float_into_scalar(n, fty, neg)?;
             (ty::ValTree::from_scalar_int(tcx, bits), Ty::new_float(tcx, fty))
         }
-        (ast::LitKind::Float(n, ast::LitFloatType::Unsuffixed), ty::Float(fty)) => {
+        (ast::LitKind::Float(n, ast::LitFloatType::Unsuffixed), Some(ty::Float(fty))) => {
             let bits = parse_float_into_scalar(n, *fty, neg)?;
             (ty::ValTree::from_scalar_int(tcx, bits), Ty::new_float(tcx, *fty))
         }

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -696,7 +696,7 @@ impl<'tcx> PatCtxt<'tcx> {
                 // patterns to `str`, and byte-string literal patterns to `[u8; N]` or `[u8]`.
 
                 let pat_ty = self.typeck_results.node_type(pat.hir_id);
-                let lit_input = LitToConstInput { lit: lit.node, ty: pat_ty, neg: *negated };
+                let lit_input = LitToConstInput { lit: lit.node, ty: Some(pat_ty), neg: *negated };
                 let constant = const_lit_matches_ty(self.tcx, &lit.node, pat_ty, *negated)
                     .then(|| self.tcx.at(expr.span).lit_to_const(lit_input))
                     .flatten()

compiler/rustc_ty_utils/src/consts.rs

@@ -58,7 +58,8 @@ fn recurse_build<'tcx>(
         }
         &ExprKind::Literal { lit, neg } => {
             let sp = node.span;
-            match tcx.at(sp).lit_to_const(LitToConstInput { lit: lit.node, ty: node.ty, neg }) {
+            match tcx.at(sp).lit_to_const(LitToConstInput { lit: lit.node, ty: Some(node.ty), neg })
+            {
                 Some(value) => ty::Const::new_value(tcx, value.valtree, value.ty),
                 None => ty::Const::new_misc_error(tcx),
             }

src/bootstrap/src/utils/exec.rs

@@ -7,6 +7,7 @@
 //! relevant to command execution in the bootstrap process. This includes settings such as
 //! dry-run mode, verbosity level, and failure behavior.
 
+use std::backtrace::{Backtrace, BacktraceStatus};
 use std::collections::HashMap;
 use std::ffi::{OsStr, OsString};
 use std::fmt::{Debug, Formatter};
@@ -930,6 +931,16 @@ Executed at: {executed_at}"#,
             if stderr.captures() {
                 writeln!(error_message, "\n--- STDERR vvv\n{}", output.stderr().trim()).unwrap();
             }
+            let backtrace = if exec_ctx.verbosity > 1 {
+                Backtrace::force_capture()
+            } else if matches!(command.failure_behavior, BehaviorOnFailure::Ignore) {
+                Backtrace::disabled()
+            } else {
+                Backtrace::capture()
+            };
+            if matches!(backtrace.status(), BacktraceStatus::Captured) {
+                writeln!(error_message, "\n--- BACKTRACE vvv\n{backtrace}").unwrap();
+            }
 
             match command.failure_behavior {
                 BehaviorOnFailure::DelayFail => {

tests/ui/const-generics/mgca/braced-const-infer.rs

@@ -0,0 +1,9 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/153198
+#![feature(min_generic_const_args)]
+#![allow(incomplete_features, rust_2021_compatibility)]
+
+trait Trait<T> {}
+
+impl dyn Trait<{_}> {} //~ ERROR: the placeholder `_` is not allowed within types on item signatures
+
+fn main() {}

tests/ui/const-generics/mgca/braced-const-infer.stderr

@@ -0,0 +1,9 @@
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for implementations
+  --> $DIR/braced-const-infer.rs:7:17
+   |
+LL | impl dyn Trait<{_}> {}
+   |                 ^ not allowed in type signatures
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0121`.

tests/ui/const-generics/mgca/infer-vars-in-const-args-conflicting.rs

@@ -0,0 +1,21 @@
+//! This test ensures compilation failure when trying to pass literals
+//! without explicitly stated type as inference variables in generic arguments.
+//!
+//! See https://github.com/rust-lang/rust/pull/153557
+
+#![allow(incomplete_features)]
+#![feature(adt_const_params, min_generic_const_args, generic_const_parameter_types)]
+
+fn main() {
+    foo::<_, { 2 }>();
+    //~^ ERROR: type annotations needed for the literal
+    let _: PC<_, { 42 }> = PC { a: 1, b: 1 };
+    //~^ ERROR: type annotations needed for the literal
+}
+
+struct PC<T, const N: T> {
+//~^ ERROR: `T` can't be used as a const parameter type [E0741]
+    a: T,
+}
+
+fn foo<const N: usize, const A: [u8; N]>() {}

tests/ui/const-generics/mgca/infer-vars-in-const-args-conflicting.stderr

@@ -0,0 +1,21 @@
+error[E0741]: `T` can't be used as a const parameter type
+  --> $DIR/infer-vars-in-const-args-conflicting.rs:16:23
+   |
+LL | struct PC<T, const N: T> {
+   |                       ^
+
+error: type annotations needed for the literal
+  --> $DIR/infer-vars-in-const-args-conflicting.rs:10:16
+   |
+LL |     foo::<_, { 2 }>();
+   |                ^
+
+error: type annotations needed for the literal
+  --> $DIR/infer-vars-in-const-args-conflicting.rs:12:20
+   |
+LL |     let _: PC<_, { 42 }> = PC { a: 1, b: 1 };
+   |                    ^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0741`.

tests/ui/const-generics/mgca/infer-vars-in-const-args-correct.rs

@@ -0,0 +1,22 @@
+//! This test ensures no errors are emitted when lowering literals with
+//! explicitly stated types and inference variables in the type of the const
+//! generic parameter.
+//!
+//! See https://github.com/rust-lang/rust/pull/153557
+
+//@check-pass
+
+#![allow(incomplete_features)]
+#![feature(adt_const_params,
+    min_generic_const_args,
+    generic_const_parameter_types,
+    unsized_const_params
+)]
+
+use std::marker::ConstParamTy_;
+
+fn main() {
+    foo::<_, 2_i32>();
+}
+
+fn foo<T: ConstParamTy_, const N: T>() {}

tests/ui/const-generics/mgca/macro-const-arg-infer.rs

@@ -0,0 +1,20 @@
+//! Regression test for https://github.com/rust-lang/rust/issues/153198
+#![feature(min_generic_const_args)]
+#![allow(incomplete_features)]
+macro_rules! y {
+    ( $($matcher:tt)*) => {
+        _ //~ ERROR: the placeholder `_` is not allowed within types on item signatures
+    };
+}
+
+struct A<T>; //~ ERROR: type parameter `T` is never used
+
+const y: A<
+    {
+        y! {
+            x
+        }
+    },
+> = 1; //~ ERROR: mismatched types
+
+fn main() {}

tests/ui/const-generics/mgca/macro-const-arg-infer.stderr

@@ -0,0 +1,44 @@
+error[E0392]: type parameter `T` is never used
+  --> $DIR/macro-const-arg-infer.rs:10:10
+   |
+LL | struct A<T>;
+   |          ^ unused type parameter
+   |
+   = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
+   = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead
+
+error[E0308]: mismatched types
+  --> $DIR/macro-const-arg-infer.rs:18:5
+   |
+LL |   const y: A<
+   |  __________-
+LL | |     {
+LL | |         y! {
+LL | |             x
+LL | |         }
+LL | |     },
+LL | | > = 1;
+   | | -   ^ expected `A<_>`, found integer
+   | |_|
+   |   expected because of the type of the constant
+   |
+   = note: expected struct `A<_>`
+                found type `{integer}`
+
+error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
+  --> $DIR/macro-const-arg-infer.rs:6:9
+   |
+LL |           _
+   |           ^ not allowed in type signatures
+...
+LL | /         y! {
+LL | |             x
+LL | |         }
+   | |_________- in this macro invocation
+   |
+   = note: this error originates in the macro `y` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0121, E0308, E0392.
+For more information about an error, try `rustc --explain E0121`.