Rollup merge of #96868 - nrc:turbo-stable, r=jhpratt,nbdd0121,nagisa

Stabilize explicit_generic_args_with_impl_trait

This is a stabilisation PR for `explicit_generic_args_with_impl_trait`.

* [tracking issue](https://github.com/rust-lang/rust/issues/83701)
  - [Stabilisation report](https://github.com/rust-lang/rust/issues/83701#issuecomment-1109949897)
  - [FCP entered](https://github.com/rust-lang/rust/issues/83701#issuecomment-1120285703)
* [implementation PR](https://github.com/rust-lang/rust/pull/86176)
* [Reference PR](https://github.com/rust-lang/reference/pull/1212)
* There is no mention of using the turbofish operator in the book (other than an entry in the operator list in the appendix), so there is no documentation to change/add there, unless we felt like we should add a section on using turbofish, but that seems orthogonal to `explicit_generic_args_with_impl_trait`
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Dylan DPC 2022-06-11 07:42:12 +02:00 committed by GitHub
commit f1f44b9e4d
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23 changed files with 32 additions and 222 deletions

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@ -1,9 +1,11 @@
#### Note: this error code is no longer emitted by the compiler.
An explicit generic argument was provided when calling a function that
uses `impl Trait` in argument position.
Erroneous code example:
```compile_fail,E0632
```ignore (no longer an error)
fn foo<T: Copy>(a: T, b: impl Clone) {}
foo::<i32>(0i32, "abc".to_string());

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@ -95,12 +95,6 @@ typeck-expected-return-type = expected `{$expected}` because of return type
typeck-unconstrained-opaque-type = unconstrained opaque type
.note = `{$name}` must be used in combination with a concrete type within the same module
typeck-explicit-generic-args-with-impl-trait =
cannot provide explicit generic arguments when `impl Trait` is used in argument position
.label = explicit generic argument not allowed
.note = see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
.help = add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
typeck-missing-type-params =
the type {$parameterCount ->
[one] parameter

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@ -142,6 +142,8 @@ declare_features! (
(accepted, dyn_trait, "1.27.0", Some(44662), None),
/// Allows integer match exhaustiveness checking (RFC 2591).
(accepted, exhaustive_integer_patterns, "1.33.0", Some(50907), None),
/// Allows explicit generic arguments specification with `impl Trait` present.
(accepted, explicit_generic_args_with_impl_trait, "1.63.0", Some(83701), None),
/// Allows arbitrary expressions in key-value attributes at parse time.
(accepted, extended_key_value_attributes, "1.54.0", Some(78835), None),
/// Allows resolving absolute paths as paths from other crates.

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@ -383,8 +383,6 @@ declare_features! (
(active, exclusive_range_pattern, "1.11.0", Some(37854), None),
/// Allows exhaustive pattern matching on types that contain uninhabited types.
(active, exhaustive_patterns, "1.13.0", Some(51085), None),
/// Allows explicit generic arguments specification with `impl Trait` present.
(active, explicit_generic_args_with_impl_trait, "1.56.0", Some(83701), None),
/// Allows defining `extern type`s.
(active, extern_types, "1.23.0", Some(43467), None),
/// Allows the use of `#[ffi_const]` on foreign functions.

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@ -3,7 +3,7 @@ use crate::astconv::{
AstConv, CreateSubstsForGenericArgsCtxt, ExplicitLateBound, GenericArgCountMismatch,
GenericArgCountResult, GenericArgPosition,
};
use crate::errors::{AssocTypeBindingNotAllowed, ExplicitGenericArgsWithImplTrait};
use crate::errors::AssocTypeBindingNotAllowed;
use crate::structured_errors::{GenericArgsInfo, StructuredDiagnostic, WrongNumberOfGenericArgs};
use rustc_ast::ast::ParamKindOrd;
use rustc_errors::{struct_span_err, Applicability, Diagnostic, MultiSpan};
@ -397,8 +397,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
is_method_call: IsMethodCall,
) -> GenericArgCountResult {
let empty_args = hir::GenericArgs::none();
let suppress_mismatch = Self::check_impl_trait(tcx, seg, generics);
let gen_args = seg.args.unwrap_or(&empty_args);
let gen_pos = if is_method_call == IsMethodCall::Yes {
GenericArgPosition::MethodCall
@ -406,10 +404,17 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
GenericArgPosition::Value
};
let has_self = generics.parent.is_none() && generics.has_self;
let infer_args = seg.infer_args || suppress_mismatch;
Self::check_generic_arg_count(
tcx, span, def_id, seg, generics, gen_args, gen_pos, has_self, infer_args,
tcx,
span,
def_id,
seg,
generics,
gen_args,
gen_pos,
has_self,
seg.infer_args,
)
}
@ -431,19 +436,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let param_counts = gen_params.own_counts();
// Subtracting from param count to ensure type params synthesized from `impl Trait`
// cannot be explicitly specified even with `explicit_generic_args_with_impl_trait`
// feature enabled.
let synth_type_param_count = if tcx.features().explicit_generic_args_with_impl_trait {
gen_params
.params
.iter()
.filter(|param| {
matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: true, .. })
})
.count()
} else {
0
};
// cannot be explicitly specified.
let synth_type_param_count = gen_params
.params
.iter()
.filter(|param| {
matches!(param.kind, ty::GenericParamDefKind::Type { synthetic: true, .. })
})
.count();
let named_type_param_count =
param_counts.types - has_self as usize - synth_type_param_count;
let infer_lifetimes =
@ -611,40 +611,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
}
}
/// Report error if there is an explicit type parameter when using `impl Trait`.
pub(crate) fn check_impl_trait(
tcx: TyCtxt<'_>,
seg: &hir::PathSegment<'_>,
generics: &ty::Generics,
) -> bool {
if seg.infer_args || tcx.features().explicit_generic_args_with_impl_trait {
return false;
}
let impl_trait = generics.has_impl_trait();
if impl_trait {
let spans = seg
.args()
.args
.iter()
.filter_map(|arg| match arg {
GenericArg::Infer(_) | GenericArg::Type(_) | GenericArg::Const(_) => {
Some(arg.span())
}
_ => None,
})
.collect::<Vec<_>>();
tcx.sess.emit_err(ExplicitGenericArgsWithImplTrait {
spans,
is_nightly_build: tcx.sess.is_nightly_build().then_some(()),
});
}
impl_trait
}
/// Emits an error regarding forbidden type binding associations
pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_>, span: Span) {
tcx.sess.emit_err(AssocTypeBindingNotAllowed { span });

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@ -241,17 +241,6 @@ pub struct UnconstrainedOpaqueType {
pub name: Symbol,
}
#[derive(SessionDiagnostic)]
#[error(code = "E0632", slug = "typeck-explicit-generic-args-with-impl-trait")]
#[note]
pub struct ExplicitGenericArgsWithImplTrait {
#[primary_span]
#[label]
pub spans: Vec<Span>,
#[help]
pub is_nightly_build: Option<()>,
}
pub struct MissingTypeParams {
pub span: Span,
pub def_span: Span,

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@ -1,53 +0,0 @@
# `explicit_generic_args_with_impl_trait`
The tracking issue for this feature is: [#83701]
[#83701]: https://github.com/rust-lang/rust/issues/83701
------------------------
The `explicit_generic_args_with_impl_trait` feature gate lets you specify generic arguments even
when `impl Trait` is used in argument position.
A simple example is:
```rust
#![feature(explicit_generic_args_with_impl_trait)]
fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
fn main() {
foo::<str>("".to_string());
}
```
This is currently rejected:
```text
error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
--> src/main.rs:6:11
|
6 | foo::<str>("".to_string());
| ^^^ explicit generic argument not allowed
```
However it would compile if `explicit_generic_args_with_impl_trait` is enabled.
Note that the synthetic type parameters from `impl Trait` are still implicit and you
cannot explicitly specify these:
```rust,compile_fail
#![feature(explicit_generic_args_with_impl_trait)]
fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
fn bar<T: ?Sized, F: AsRef<T>>(_f: F) {}
fn main() {
bar::<str, _>("".to_string()); // Okay
bar::<str, String>("".to_string()); // Okay
foo::<str>("".to_string()); // Okay
foo::<str, String>("".to_string()); // Error, you cannot specify `impl Trait` explicitly
}
```

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@ -1,12 +0,0 @@
error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
--> $DIR/impl-trait-with-const-arguments.rs:18:20
|
LL | assert_eq!(f::<4usize>(Usizable), 20usize);
| ^^^^^^ explicit generic argument not allowed
|
= note: see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
= help: add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0632`.

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@ -1,3 +1,5 @@
// check-pass
trait Usizer {
fn m(self) -> usize;
}
@ -16,5 +18,4 @@ impl Usizer for Usizable {
fn main() {
assert_eq!(f::<4usize>(Usizable), 20usize);
//~^ ERROR cannot provide explicit generic arguments when `impl Trait` is used in argument position
}

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@ -1,5 +1,3 @@
#![feature(explicit_generic_args_with_impl_trait)]
fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
fn main() {

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@ -1,5 +1,5 @@
error[E0107]: this function takes 1 generic argument but 2 generic arguments were supplied
--> $DIR/explicit-generic-args-for-impl.rs:6:5
--> $DIR/explicit-generic-args-for-impl.rs:4:5
|
LL | foo::<str, String>("".to_string());
| ^^^ ------ help: remove this generic argument
@ -7,7 +7,7 @@ LL | foo::<str, String>("".to_string());
| expected 1 generic argument
|
note: function defined here, with 1 generic parameter: `T`
--> $DIR/explicit-generic-args-for-impl.rs:3:4
--> $DIR/explicit-generic-args-for-impl.rs:1:4
|
LL | fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
| ^^^ -

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@ -1,7 +1,5 @@
// check-pass
#![feature(explicit_generic_args_with_impl_trait)]
fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
fn main() {

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@ -1,7 +0,0 @@
// gate-test-explicit_generic_args_with_impl_trait
fn foo<T: ?Sized>(_f: impl AsRef<T>) {}
fn main() {
foo::<str>("".to_string()); //~ ERROR E0632
}

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@ -1,12 +0,0 @@
error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
--> $DIR/feature-gate.rs:6:11
|
LL | foo::<str>("".to_string());
| ^^^ explicit generic argument not allowed
|
= note: see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
= help: add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0632`.

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@ -1,7 +1,5 @@
// check-pass
#![feature(explicit_generic_args_with_impl_trait)]
fn f<T: ?Sized>(_: impl AsRef<T>, _: impl AsRef<T>) {}
fn main() {

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@ -1,5 +1,3 @@
#![feature(explicit_generic_args_with_impl_trait)]
fn f<T: ?Sized, U: ?Sized>(_: impl AsRef<T>, _: impl AsRef<U>) {}
fn main() {

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@ -1,5 +1,5 @@
error[E0107]: this function takes 2 generic arguments but 1 generic argument was supplied
--> $DIR/not-enough-args.rs:6:5
--> $DIR/not-enough-args.rs:4:5
|
LL | f::<[u8]>("a", b"a");
| ^ ---- supplied 1 generic argument
@ -7,7 +7,7 @@ LL | f::<[u8]>("a", b"a");
| expected 2 generic arguments
|
note: function defined here, with 2 generic parameters: `T`, `U`
--> $DIR/not-enough-args.rs:3:4
--> $DIR/not-enough-args.rs:1:4
|
LL | fn f<T: ?Sized, U: ?Sized>(_: impl AsRef<T>, _: impl AsRef<U>) {}
| ^ - -

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@ -1,7 +0,0 @@
use std::fmt::Debug;
fn foo<T>(x: impl Debug) { }
fn main() {
foo::<String>('a'); //~ ERROR cannot provide explicit generic arguments
}

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@ -1,12 +0,0 @@
error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
--> $DIR/universal-issue-48703.rs:6:11
|
LL | foo::<String>('a');
| ^^^^^^ explicit generic argument not allowed
|
= note: see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
= help: add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0632`.

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@ -1,17 +0,0 @@
use std::any::Any;
pub struct EventHandler {
}
impl EventHandler
{
pub fn handle_event<T: Any>(&mut self, _efunc: impl FnMut(T)) {}
}
struct TestEvent(i32);
fn main() {
let mut evt = EventHandler {};
evt.handle_event::<TestEvent, fn(TestEvent)>(|_evt| {
//~^ ERROR cannot provide explicit generic arguments
});
}

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@ -1,14 +0,0 @@
error[E0632]: cannot provide explicit generic arguments when `impl Trait` is used in argument position
--> $DIR/universal-turbofish-in-method-issue-50950.rs:14:24
|
LL | evt.handle_event::<TestEvent, fn(TestEvent)>(|_evt| {
| ^^^^^^^^^ ^^^^^^^^^^^^^ explicit generic argument not allowed
| |
| explicit generic argument not allowed
|
= note: see issue #83701 <https://github.com/rust-lang/rust/issues/83701> for more information
= help: add `#![feature(explicit_generic_args_with_impl_trait)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0632`.

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@ -5,6 +5,6 @@ fn foo<const N: usize>(_: impl std::fmt::Display) -> [usize; N] {
}
fn main() {
let _ = foo("foo"); //<- Do not suggest `foo::<N>("foo");`!
let _ = foo("foo");
//~^ ERROR: type annotations needed for `[usize; _]`
}

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@ -1,12 +1,12 @@
error[E0282]: type annotations needed for `[usize; _]`
--> $DIR/issue-83606.rs:8:9
|
LL | let _ = foo("foo"); //<- Do not suggest `foo::<N>("foo");`!
LL | let _ = foo("foo");
| ^
|
help: consider giving this pattern a type, where the the value of const parameter `N` is specified
|
LL | let _: [usize; _] = foo("foo"); //<- Do not suggest `foo::<N>("foo");`!
LL | let _: [usize; _] = foo("foo");
| ++++++++++++
error: aborting due to previous error