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Unconditionally lower generic_arg_infer

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This commit is contained in:
Michael Goulet 2025-01-02 18:49:43 +00:00
parent b85a91fc59
commit 6885ff4a7b
10 changed files with 91 additions and 119 deletions
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9
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -2031,11 +2031,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
fn lower_array_length_to_const_arg(&mut self, c: &AnonConst) -> &'hir hir::ConstArg<'hir> {
match c.value.kind {
ExprKind::Underscore => {
if self.tcx.features().generic_arg_infer() {
let ct_kind = hir::ConstArgKind::Infer(self.lower_span(c.value.span));
self.arena
.alloc(hir::ConstArg { hir_id: self.lower_node_id(c.id), kind: ct_kind })
} else {
if !self.tcx.features().generic_arg_infer() {
feature_err(
&self.tcx.sess,
sym::generic_arg_infer,
@ -2043,8 +2039,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
fluent_generated::ast_lowering_underscore_array_length_unstable,
)
.stash(c.value.span, StashKey::UnderscoreForArrayLengths);
self.lower_anon_const_to_const_arg(c)
}
let ct_kind = hir::ConstArgKind::Infer(self.lower_span(c.value.span));
self.arena.alloc(hir::ConstArg { hir_id: self.lower_node_id(c.id), kind: ct_kind })
}
_ => self.lower_anon_const_to_const_arg(c),
}

17
compiler/rustc_hir_analysis/src/collect/type_of.rs
View file

@ -452,6 +452,12 @@ fn infer_placeholder_type<'tcx>(
if let Some(ty) = tcx.hir_node_by_def_id(def_id).ty() {
visitor.visit_ty(ty);
}
// If we have just one span, let's try to steal a const `_` feature error.
let try_steal_span = if !tcx.features().generic_arg_infer() && visitor.0.len() == 1 {
visitor.0.first().copied()
} else {
None
};
// If we didn't find any infer tys, then just fallback to `span``.
if visitor.0.is_empty() {
visitor.0.push(span);
@ -473,7 +479,16 @@ fn infer_placeholder_type<'tcx>(
));
}
}
diag.emit()
if let Some(try_steal_span) = try_steal_span {
cx.dcx().try_steal_replace_and_emit_err(
try_steal_span,
StashKey::UnderscoreForArrayLengths,
diag,
)
} else {
diag.emit()
}
});
Ty::new_error(tcx, guar)
}

1
compiler/rustc_hir_typeck/src/expr.rs
View file

@ -1774,7 +1774,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let Some((
_,
hir::Node::LetStmt(hir::LetStmt { ty: Some(ty), .. })
| hir::Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, _, _), .. }),
)) = parent_node
else {
return;

25
tests/ui/array-slice-vec/suggest-array-length.fixed
View file

@ -3,24 +3,21 @@
fn main() {
const Foo: [i32; 3] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
const REF_FOO: &[u8; 1] = &[1];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
static Statik: [i32; 3] = [1, 2, 3];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
static REF_STATIK: &[u8; 1] = &[1];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
let foo: [i32; 3] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let bar: [i32; 3] = [0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_foo: &[i32; 3] = &[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_bar: &[i32; 3] = &[0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let multiple_ref_foo: &&[i32; 3] = &&[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
}

25
tests/ui/array-slice-vec/suggest-array-length.rs
View file

@ -3,24 +3,21 @@
fn main() {
const Foo: [i32; _] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
const REF_FOO: &[u8; _] = &[1];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for constants
static Statik: [i32; _] = [1, 2, 3];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
static REF_STATIK: &[u8; _] = &[1];
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for static variables
let foo: [i32; _] = [1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let bar: [i32; _] = [0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_foo: &[i32; _] = &[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let ref_bar: &[i32; _] = &[0; 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
//~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
//~| ERROR using `_` for array lengths is unstable
//~^ ERROR using `_` for array lengths is unstable
}

97
tests/ui/array-slice-vec/suggest-array-length.stderr
View file

@ -1,67 +1,41 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:11:20
|
LL | let foo: [i32; _] = [1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:14:20
|
LL | let bar: [i32; _] = [0; 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:17:25
|
LL | let ref_foo: &[i32; _] = &[1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:20:25
|
LL | let ref_bar: &[i32; _] = &[0; 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:23:35
|
LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/suggest-array-length.rs:5:22
|
LL | const Foo: [i32; _] = [1, 2, 3];
| ^ `_` not allowed here
| ------^-
| | |
| | not allowed in type signatures
| help: replace with the correct type: `[i32; 3]`
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/suggest-array-length.rs:8:26
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/suggest-array-length.rs:7:26
|
LL | const REF_FOO: &[u8; _] = &[1];
| ^ `_` not allowed here
| ------^-
| | |
| | not allowed in type signatures
| help: replace with the correct type: `&[u8; 1]`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/suggest-array-length.rs:9:26
|
LL | static Statik: [i32; _] = [1, 2, 3];
| ------^-
| | |
| | not allowed in type signatures
| help: replace with the correct type: `[i32; 3]`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/suggest-array-length.rs:11:30
|
LL | static REF_STATIK: &[u8; _] = &[1];
| ------^-
| | |
| | not allowed in type signatures
| help: replace with the correct type: `&[u8; 1]`
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:5:22
|
LL | const Foo: [i32; _] = [1, 2, 3];
| ^ help: consider specifying the array length: `3`
|
= note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:8:26
|
LL | const REF_FOO: &[u8; _] = &[1];
| ^ help: consider specifying the array length: `1`
|
= note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:11:20
--> $DIR/suggest-array-length.rs:13:20
|
LL | let foo: [i32; _] = [1, 2, 3];
| ^ help: consider specifying the array length: `3`
@ -71,7 +45,7 @@ LL | let foo: [i32; _] = [1, 2, 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:14:20
--> $DIR/suggest-array-length.rs:15:20
|
LL | let bar: [i32; _] = [0; 3];
| ^ help: consider specifying the array length: `3`
@ -91,7 +65,7 @@ LL | let ref_foo: &[i32; _] = &[1, 2, 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:20:25
--> $DIR/suggest-array-length.rs:19:25
|
LL | let ref_bar: &[i32; _] = &[0; 3];
| ^ help: consider specifying the array length: `3`
@ -101,7 +75,7 @@ LL | let ref_bar: &[i32; _] = &[0; 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0658]: using `_` for array lengths is unstable
--> $DIR/suggest-array-length.rs:23:35
--> $DIR/suggest-array-length.rs:21:35
|
LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
| ^ help: consider specifying the array length: `3`
@ -110,6 +84,7 @@ LL | let multiple_ref_foo: &&[i32; _] = &&[1, 2, 3];
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error: aborting due to 14 previous errors
error: aborting due to 9 previous errors
For more information about this error, try `rustc --explain E0658`.
Some errors have detailed explanations: E0121, E0658.
For more information about an error, try `rustc --explain E0121`.

4
tests/ui/async-await/issues/issue-95307.rs
View file

@ -5,8 +5,8 @@
pub trait C {
async fn new() -> [u8; _];
//~^ ERROR: using `_` for array lengths is unstable
//~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
//~^ ERROR: the placeholder `_` is not allowed within types on item signatures for functions
//~| ERROR using `_` for array lengths is unstable
}
fn main() {}

12
tests/ui/async-await/issues/issue-95307.stderr
View file

@ -1,8 +1,13 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
error[E0121]: the placeholder `_` is not allowed within types on item signatures for functions
--> $DIR/issue-95307.rs:7:28
|
LL | async fn new() -> [u8; _];
| ^ `_` not allowed here
| ^ not allowed in type signatures
|
help: use type parameters instead
|
LL | async fn new<T>() -> [u8; T];
| +++ ~
error[E0658]: using `_` for array lengths is unstable
--> $DIR/issue-95307.rs:7:28
@ -16,4 +21,5 @@ LL | async fn new() -> [u8; _];
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0658`.
Some errors have detailed explanations: E0121, E0658.
For more information about an error, try `rustc --explain E0121`.

18
tests/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr
View file

@ -1,17 +1,5 @@
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/feature-gate-generic_arg_infer.rs:11:27
|
LL | let _x: [u8; 3] = [0; _];
| ^ `_` not allowed here
error: in expressions, `_` can only be used on the left-hand side of an assignment
--> $DIR/feature-gate-generic_arg_infer.rs:14:18
|
LL | let _y: [u8; _] = [0; 3];
| ^ `_` not allowed here
error[E0658]: using `_` for array lengths is unstable
--> $DIR/feature-gate-generic_arg_infer.rs:14:18
--> $DIR/feature-gate-generic_arg_infer.rs:13:18
|
LL | let _y: [u8; _] = [0; 3];
| ^ help: consider specifying the array length: `3`
@ -21,7 +9,7 @@ LL | let _y: [u8; _] = [0; 3];
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error[E0747]: type provided when a constant was expected
--> $DIR/feature-gate-generic_arg_infer.rs:20:20
--> $DIR/feature-gate-generic_arg_infer.rs:18:20
|
LL | let _x = foo::<_>([1,2]);
| ^
@ -42,7 +30,7 @@ LL | let _x: [u8; 3] = [0; _];
= help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
error: aborting due to 5 previous errors
error: aborting due to 3 previous errors
Some errors have detailed explanations: E0658, E0747.
For more information about an error, try `rustc --explain E0658`.

2
tests/ui/feature-gates/feature-gate-generic_arg_infer.rs
View file

@ -10,10 +10,8 @@ fn foo<const N: usize>(_: [u8; N]) -> [u8; N] {
fn bar() {
let _x: [u8; 3] = [0; _];
//[normal]~^ ERROR: using `_` for array lengths is unstable
//[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
let _y: [u8; _] = [0; 3];
//[normal]~^ ERROR: using `_` for array lengths is unstable
//[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
}
fn main() {