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Fix the span of trait bound modifier [const] #143171

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Merged
merged 1 commit into from
Jun 29, 2025
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Fix the span of trait bound modifier [const] #143171

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2 changes: 1 addition & 1 deletion compiler/rustc_parse/src/parser/ty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1071,7 +1071,7 @@ impl<'a> Parser<'a> {
&& self.look_ahead(1, |t| t.is_keyword(kw::Const))
&& self.look_ahead(2, |t| *t == token::CloseBracket)
Comment on lines 1071 to 1072
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@fmease fmease Jun 29, 2025 •
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(I'm pretty sure we don't need the careful lookahead logic and could just if eat("[") then expect("const") expect("]"), there shouldn't be ambiguity issues (I'll post another, tangentially related PR later that goes into more detail) but that will likely regress diagnostics (because if we fail to parse a bound, we try to reparse it as a type to give "expected trait, found type") and I didn't want to deal with that rn and maybe that's why oli chose this approach)

{
let start = self.prev_token.span;
let start = self.token.span;
self.bump();
self.expect_keyword(exp!(Const)).unwrap();
self.bump();
Expand Down
60 changes: 30 additions & 30 deletions tests/ui/consts/fn_trait_refs.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -5,145 +5,145 @@ LL | #![feature(const_fn_trait_ref_impls)]
| ^^^^^^^^^^^^^^^^^^^^^^^^

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:14:6
--> $DIR/fn_trait_refs.rs:14:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:14:6
--> $DIR/fn_trait_refs.rs:14:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:14:6
--> $DIR/fn_trait_refs.rs:14:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:21:6
--> $DIR/fn_trait_refs.rs:21:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:21:6
--> $DIR/fn_trait_refs.rs:21:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:21:6
--> $DIR/fn_trait_refs.rs:21:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:28:6
--> $DIR/fn_trait_refs.rs:28:8
|
LL | T: [const] FnOnce<()>,
| ^^^^^^^^^ can't be applied to `FnOnce`
| ^^^^^^^ can't be applied to `FnOnce`
|
note: `FnOnce` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:28:6
--> $DIR/fn_trait_refs.rs:28:8
|
LL | T: [const] FnOnce<()>,
| ^^^^^^^^^ can't be applied to `FnOnce`
| ^^^^^^^ can't be applied to `FnOnce`
|
note: `FnOnce` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:28:6
--> $DIR/fn_trait_refs.rs:28:8
|
LL | T: [const] FnOnce<()>,
| ^^^^^^^^^ can't be applied to `FnOnce`
| ^^^^^^^ can't be applied to `FnOnce`
|
note: `FnOnce` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:35:6
--> $DIR/fn_trait_refs.rs:35:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:35:6
--> $DIR/fn_trait_refs.rs:35:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:35:6
--> $DIR/fn_trait_refs.rs:35:8
|
LL | T: [const] Fn<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:49:6
--> $DIR/fn_trait_refs.rs:49:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:49:6
--> $DIR/fn_trait_refs.rs:49:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/fn_trait_refs.rs:49:6
--> $DIR/fn_trait_refs.rs:49:8
|
LL | T: [const] FnMut<()> + [const] Destruct,
| ^^^^^^^^^ can't be applied to `FnMut`
| ^^^^^^^ can't be applied to `FnMut`
|
note: `FnMut` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
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8 changes: 4 additions & 4 deletions tests/ui/consts/unstable-const-fn-in-libcore.stderr
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@@ -1,17 +1,17 @@
error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/unstable-const-fn-in-libcore.rs:19:30
--> $DIR/unstable-const-fn-in-libcore.rs:19:32
|
LL | const fn unwrap_or_else<F: [const] FnOnce() -> T>(self, f: F) -> T {
| ^^^^^^^^^ can't be applied to `FnOnce`
| ^^^^^^^ can't be applied to `FnOnce`
|
note: `FnOnce` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/unstable-const-fn-in-libcore.rs:19:30
--> $DIR/unstable-const-fn-in-libcore.rs:19:32
|
LL | const fn unwrap_or_else<F: [const] FnOnce() -> T>(self, f: F) -> T {
| ^^^^^^^^^ can't be applied to `FnOnce`
| ^^^^^^^ can't be applied to `FnOnce`
|
note: `FnOnce` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
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8 changes: 4 additions & 4 deletions tests/ui/impl-trait/normalize-tait-in-const.stderr
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@@ -1,17 +1,17 @@
error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/normalize-tait-in-const.rs:27:33
--> $DIR/normalize-tait-in-const.rs:27:35
|
LL | const fn with_positive<F: for<'a> [const] Fn(&'a Alias<'a>) + [const] Destruct>(fun: F) {
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/normalize-tait-in-const.rs:27:33
--> $DIR/normalize-tait-in-const.rs:27:35
|
LL | const fn with_positive<F: for<'a> [const] Fn(&'a Alias<'a>) + [const] Destruct>(fun: F) {
| ^^^^^^^^^ can't be applied to `Fn`
| ^^^^^^^ can't be applied to `Fn`
|
note: `Fn` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
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4 changes: 2 additions & 2 deletions tests/ui/parser/bounds-type.stderr
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Expand Up @@ -21,10 +21,10 @@ LL | T: [const] ?Tr,
| there is not a well-defined meaning for a `[const] ?` trait

error: `[const]` may only modify trait bounds, not lifetime bounds
--> $DIR/bounds-type.rs:16:6
--> $DIR/bounds-type.rs:16:8
|
LL | T: [const] 'a,
| ^^^^^^^^^
| ^^^^^^^

error: `const` may only modify trait bounds, not lifetime bounds
--> $DIR/bounds-type.rs:17:8
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24 changes: 12 additions & 12 deletions tests/ui/specialization/const_trait_impl.stderr
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Original file line number Diff line number Diff line change
@@ -1,55 +1,55 @@
error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:34:7
--> $DIR/const_trait_impl.rs:34:9
|
LL | impl<T: [const] Default> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:40:7
--> $DIR/const_trait_impl.rs:40:9
|
LL | impl<T: [const] Default + [const] Sup> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:46:7
--> $DIR/const_trait_impl.rs:46:9
|
LL | impl<T: [const] Default + [const] Sub> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:40:7
--> $DIR/const_trait_impl.rs:40:9
|
LL | impl<T: [const] Default + [const] Sup> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:34:7
--> $DIR/const_trait_impl.rs:34:9
|
LL | impl<T: [const] Default> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: `[const]` can only be applied to `#[const_trait]` traits
--> $DIR/const_trait_impl.rs:46:7
--> $DIR/const_trait_impl.rs:46:9
|
LL | impl<T: [const] Default + [const] Sub> const A for T {
| ^^^^^^^^^ can't be applied to `Default`
| ^^^^^^^ can't be applied to `Default`
|
note: `Default` can't be used with `[const]` because it isn't annotated with `#[const_trait]`
--> $SRC_DIR/core/src/default.rs:LL:COL
Expand Down
8 changes: 4 additions & 4 deletions tests/ui/traits/const-traits/conditionally-const-and-const-params.stderr
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@@ -1,8 +1,8 @@
error: `[const]` is not allowed here
--> $DIR/conditionally-const-and-const-params.rs:8:13
--> $DIR/conditionally-const-and-const-params.rs:8:15
|
LL | fn add<A: [const] Add42>(self) -> Foo<{ A::add(N) }> {
| ^^^^^^^^^
| ^^^^^^^
|
note: this function is not `const`, so it cannot have `[const]` trait bounds
--> $DIR/conditionally-const-and-const-params.rs:8:8
Expand All @@ -11,10 +11,10 @@ LL | fn add<A: [const] Add42>(self) -> Foo<{ A::add(N) }> {
| ^^^

error: `[const]` is not allowed here
--> $DIR/conditionally-const-and-const-params.rs:26:9
--> $DIR/conditionally-const-and-const-params.rs:26:11
|
LL | fn bar<A: [const] Add42, const N: usize>(_: Foo<N>) -> Foo<{ A::add(N) }> {
| ^^^^^^^^^
| ^^^^^^^
|
note: this function is not `const`, so it cannot have `[const]` trait bounds
--> $DIR/conditionally-const-and-const-params.rs:26:4
Expand Down
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