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Rollup merge of #135340 - obeis:explicit-extern-abis, r=traviscross,nadrieril
Add `explicit_extern_abis` Feature and Enforce Explicit ABIs The unstable `explicit_extern_abis` feature is introduced, requiring explicit ABIs in `extern` blocks. Hard errors will be enforced with this feature enabled in a future edition. RFC rust-lang/rfcs#3722 Update #134986
2 parents 78f2104 + d17c04e commit bb3e156

27 files changed

+334
-21
lines changed

‎compiler/rustc_ast_passes/messages.ftl

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@@ -79,6 +79,10 @@ ast_passes_extern_types_cannot = `type`s inside `extern` blocks cannot have {$de
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.suggestion = remove the {$remove_descr}
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.label = `extern` block begins here
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ast_passes_extern_without_abi = `extern` declarations without an explicit ABI are disallowed
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.suggestion = specify an ABI
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.help = prior to Rust 2024, a default ABI was inferred
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ast_passes_feature_on_non_nightly = `#![feature]` may not be used on the {$channel} release channel
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.suggestion = remove the attribute
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.stable_since = the feature `{$name}` has been stable since `{$since}` and no longer requires an attribute to enable

‎compiler/rustc_ast_passes/src/ast_validation.rs

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@@ -684,7 +684,7 @@ impl<'a> AstValidator<'a> {
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self.dcx().emit_err(errors::PatternFnPointer { span });
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});
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if let Extern::Implicit(extern_span) = bfty.ext {
687-
self.maybe_lint_missing_abi(extern_span, ty.id);
687+
self.handle_missing_abi(extern_span, ty.id);
688688
}
689689
}
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TyKind::TraitObject(bounds, ..) => {
@@ -717,10 +717,12 @@ impl<'a> AstValidator<'a> {
717717
}
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}
719719

720-
fn maybe_lint_missing_abi(&mut self, span: Span, id: NodeId) {
720+
fn handle_missing_abi(&mut self, span: Span, id: NodeId) {
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// FIXME(davidtwco): This is a hack to detect macros which produce spans of the
722722
// call site which do not have a macro backtrace. See #61963.
723-
if self
723+
if span.edition().at_least_edition_future() && self.features.explicit_extern_abis() {
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self.dcx().emit_err(errors::MissingAbi { span });
725+
} else if self
724726
.sess
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.source_map()
726728
.span_to_snippet(span)
@@ -996,7 +998,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
996998
}
997999

9981000
if abi.is_none() {
999-
self.maybe_lint_missing_abi(*extern_span, item.id);
1001+
self.handle_missing_abi(*extern_span, item.id);
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}
10011003
self.with_in_extern_mod(*safety, |this| {
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visit::walk_item(this, item);
@@ -1370,7 +1372,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
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},
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) = fk
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{
1373-
self.maybe_lint_missing_abi(*extern_span, id);
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self.handle_missing_abi(*extern_span, id);
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}
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// Functions without bodies cannot have patterns.

‎compiler/rustc_ast_passes/src/errors.rs

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@@ -823,3 +823,12 @@ pub(crate) struct DuplicatePreciseCapturing {
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#[label]
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pub bound2: Span,
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}
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#[derive(Diagnostic)]
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#[diag(ast_passes_extern_without_abi)]
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#[help]
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pub(crate) struct MissingAbi {
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#[primary_span]
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#[suggestion(code = "extern \"<abi>\"", applicability = "has-placeholders")]
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pub span: Span,
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}

‎compiler/rustc_feature/src/unstable.rs

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@@ -477,6 +477,8 @@ declare_features! (
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(incomplete, ergonomic_clones, "1.87.0", Some(132290)),
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/// Allows exhaustive pattern matching on types that contain uninhabited types.
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(unstable, exhaustive_patterns, "1.13.0", Some(51085)),
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/// Disallows `extern` without an explicit ABI.
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(unstable, explicit_extern_abis, "CURRENT_RUSTC_VERSION", Some(134986)),
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/// Allows explicit tail calls via `become` expression.
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(incomplete, explicit_tail_calls, "1.72.0", Some(112788)),
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/// Allows using `aapcs`, `efiapi`, `sysv64` and `win64` as calling conventions

‎compiler/rustc_lint/messages.ftl

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@@ -271,7 +271,7 @@ lint_expectation = this lint expectation is unfulfilled
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lint_extern_crate_not_idiomatic = `extern crate` is not idiomatic in the new edition
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.suggestion = convert it to a `use`
273273
274-
lint_extern_without_abi = extern declarations without an explicit ABI are deprecated
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lint_extern_without_abi = `extern` declarations without an explicit ABI are deprecated
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.label = ABI should be specified here
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.suggestion = explicitly specify the {$default_abi} ABI
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‎compiler/rustc_span/src/symbol.rs

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@@ -916,6 +916,7 @@ symbols! {
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expf16,
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expf32,
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expf64,
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explicit_extern_abis,
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explicit_generic_args_with_impl_trait,
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explicit_tail_calls,
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export_name,

‎src/doc/unstable-book/src/language-features/explicit-extern-abis.md

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# `explicit_extern_abis`
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The tracking issue for this feature is: #134986
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------
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Disallow `extern` without an explicit ABI. We should write `extern "C"`
8+
(or another ABI) instead of just `extern`.
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By making the ABI explicit, it becomes much clearer that "C" is just one of the
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possible choices, rather than the "standard" way for external functions.
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Removing the default makes it easier to add a new ABI on equal footing as "C".
13+
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```rust,editionfuture,compile_fail
15+
#![feature(explicit_extern_abis)]
16+
17+
extern fn function1() {} // ERROR `extern` declarations without an explicit ABI
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// are disallowed
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20+
extern "C" fn function2() {} // compiles
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extern "aapcs" fn function3() {} // compiles
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```

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.current.fixed

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// The purpose of this feature gate is to make something into a hard error in a
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// future edition. Consequently, this test differs from most other feature gate
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// tests. Instead of verifying that an error occurs when the feature gate is
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// missing, it ensures that the hard error is only produced with the feature
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// gate is present in the `future` edition -- and otherwise that only a warning
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// is emitted.
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//@ revisions: current current_feature future future_feature
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//@ [current] run-rustfix
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//@ [current] check-pass
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//@ [current_feature] run-rustfix
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//@ [current_feature] check-pass
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//@ [future] edition: future
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//@ [future] compile-flags: -Z unstable-options
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//@ [future] run-rustfix
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//@ [future] check-pass
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//@ [future_feature] edition: future
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//@ [future_feature] compile-flags: -Z unstable-options
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#![cfg_attr(future_feature, feature(explicit_extern_abis))]
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#![cfg_attr(current_feature, feature(explicit_extern_abis))]
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extern "C" fn _foo() {}
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//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
29+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
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//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
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//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
32+
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unsafe extern "C" fn _bar() {}
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//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
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//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
36+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
37+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
38+
39+
unsafe extern "C" {}
40+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
41+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
42+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
43+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
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fn main() {}

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.current.stderr

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warning: `extern` declarations without an explicit ABI are deprecated
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--> $DIR/feature-gate-explicit-extern-abis.rs:27:1
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|
4+
LL | extern fn _foo() {}
5+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
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|
7+
= note: `#[warn(missing_abi)]` on by default
8+
9+
warning: `extern` declarations without an explicit ABI are deprecated
10+
--> $DIR/feature-gate-explicit-extern-abis.rs:33:8
11+
|
12+
LL | unsafe extern fn _bar() {}
13+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
14+
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warning: `extern` declarations without an explicit ABI are deprecated
16+
--> $DIR/feature-gate-explicit-extern-abis.rs:39:8
17+
|
18+
LL | unsafe extern {}
19+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
20+
21+
warning: 3 warnings emitted
22+

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.current_feature.fixed

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// The purpose of this feature gate is to make something into a hard error in a
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// future edition. Consequently, this test differs from most other feature gate
3+
// tests. Instead of verifying that an error occurs when the feature gate is
4+
// missing, it ensures that the hard error is only produced with the feature
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// gate is present in the `future` edition -- and otherwise that only a warning
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// is emitted.
7+
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//@ revisions: current current_feature future future_feature
9+
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//@ [current] run-rustfix
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//@ [current] check-pass
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//@ [current_feature] run-rustfix
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//@ [current_feature] check-pass
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//@ [future] edition: future
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//@ [future] compile-flags: -Z unstable-options
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//@ [future] run-rustfix
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//@ [future] check-pass
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//@ [future_feature] edition: future
22+
//@ [future_feature] compile-flags: -Z unstable-options
23+
24+
#![cfg_attr(future_feature, feature(explicit_extern_abis))]
25+
#![cfg_attr(current_feature, feature(explicit_extern_abis))]
26+
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extern "C" fn _foo() {}
28+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
29+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
30+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
31+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
32+
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unsafe extern "C" fn _bar() {}
34+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
35+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
36+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
37+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
38+
39+
unsafe extern "C" {}
40+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
41+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
42+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
43+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
44+
45+
fn main() {}

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.current_feature.stderr

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warning: `extern` declarations without an explicit ABI are deprecated
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--> $DIR/feature-gate-explicit-extern-abis.rs:27:1
3+
|
4+
LL | extern fn _foo() {}
5+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
6+
|
7+
= note: `#[warn(missing_abi)]` on by default
8+
9+
warning: `extern` declarations without an explicit ABI are deprecated
10+
--> $DIR/feature-gate-explicit-extern-abis.rs:33:8
11+
|
12+
LL | unsafe extern fn _bar() {}
13+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
14+
15+
warning: `extern` declarations without an explicit ABI are deprecated
16+
--> $DIR/feature-gate-explicit-extern-abis.rs:39:8
17+
|
18+
LL | unsafe extern {}
19+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
20+
21+
warning: 3 warnings emitted
22+

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.future.fixed

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// The purpose of this feature gate is to make something into a hard error in a
2+
// future edition. Consequently, this test differs from most other feature gate
3+
// tests. Instead of verifying that an error occurs when the feature gate is
4+
// missing, it ensures that the hard error is only produced with the feature
5+
// gate is present in the `future` edition -- and otherwise that only a warning
6+
// is emitted.
7+
8+
//@ revisions: current current_feature future future_feature
9+
10+
//@ [current] run-rustfix
11+
//@ [current] check-pass
12+
13+
//@ [current_feature] run-rustfix
14+
//@ [current_feature] check-pass
15+
16+
//@ [future] edition: future
17+
//@ [future] compile-flags: -Z unstable-options
18+
//@ [future] run-rustfix
19+
//@ [future] check-pass
20+
21+
//@ [future_feature] edition: future
22+
//@ [future_feature] compile-flags: -Z unstable-options
23+
24+
#![cfg_attr(future_feature, feature(explicit_extern_abis))]
25+
#![cfg_attr(current_feature, feature(explicit_extern_abis))]
26+
27+
extern "C" fn _foo() {}
28+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
29+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
30+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
31+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
32+
33+
unsafe extern "C" fn _bar() {}
34+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
35+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
36+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
37+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
38+
39+
unsafe extern "C" {}
40+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
41+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
42+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
43+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
44+
45+
fn main() {}

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.future.stderr

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warning: `extern` declarations without an explicit ABI are deprecated
2+
--> $DIR/feature-gate-explicit-extern-abis.rs:27:1
3+
|
4+
LL | extern fn _foo() {}
5+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
6+
|
7+
= note: `#[warn(missing_abi)]` on by default
8+
9+
warning: `extern` declarations without an explicit ABI are deprecated
10+
--> $DIR/feature-gate-explicit-extern-abis.rs:33:8
11+
|
12+
LL | unsafe extern fn _bar() {}
13+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
14+
15+
warning: `extern` declarations without an explicit ABI are deprecated
16+
--> $DIR/feature-gate-explicit-extern-abis.rs:39:8
17+
|
18+
LL | unsafe extern {}
19+
| ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
20+
21+
warning: 3 warnings emitted
22+

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.future_feature.stderr

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error: `extern` declarations without an explicit ABI are disallowed
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--> $DIR/feature-gate-explicit-extern-abis.rs:27:1
3+
|
4+
LL | extern fn _foo() {}
5+
| ^^^^^^ help: specify an ABI: `extern "<abi>"`
6+
|
7+
= help: prior to Rust 2024, a default ABI was inferred
8+
9+
error: `extern` declarations without an explicit ABI are disallowed
10+
--> $DIR/feature-gate-explicit-extern-abis.rs:33:8
11+
|
12+
LL | unsafe extern fn _bar() {}
13+
| ^^^^^^ help: specify an ABI: `extern "<abi>"`
14+
|
15+
= help: prior to Rust 2024, a default ABI was inferred
16+
17+
error: `extern` declarations without an explicit ABI are disallowed
18+
--> $DIR/feature-gate-explicit-extern-abis.rs:39:8
19+
|
20+
LL | unsafe extern {}
21+
| ^^^^^^ help: specify an ABI: `extern "<abi>"`
22+
|
23+
= help: prior to Rust 2024, a default ABI was inferred
24+
25+
error: aborting due to 3 previous errors
26+

‎tests/ui/feature-gates/feature-gate-explicit-extern-abis.rs

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// The purpose of this feature gate is to make something into a hard error in a
2+
// future edition. Consequently, this test differs from most other feature gate
3+
// tests. Instead of verifying that an error occurs when the feature gate is
4+
// missing, it ensures that the hard error is only produced with the feature
5+
// gate is present in the `future` edition -- and otherwise that only a warning
6+
// is emitted.
7+
8+
//@ revisions: current current_feature future future_feature
9+
10+
//@ [current] run-rustfix
11+
//@ [current] check-pass
12+
13+
//@ [current_feature] run-rustfix
14+
//@ [current_feature] check-pass
15+
16+
//@ [future] edition: future
17+
//@ [future] compile-flags: -Z unstable-options
18+
//@ [future] run-rustfix
19+
//@ [future] check-pass
20+
21+
//@ [future_feature] edition: future
22+
//@ [future_feature] compile-flags: -Z unstable-options
23+
24+
#![cfg_attr(future_feature, feature(explicit_extern_abis))]
25+
#![cfg_attr(current_feature, feature(explicit_extern_abis))]
26+
27+
extern fn _foo() {}
28+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
29+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
30+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
31+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
32+
33+
unsafe extern fn _bar() {}
34+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
35+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
36+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
37+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
38+
39+
unsafe extern {}
40+
//[current]~^ WARN `extern` declarations without an explicit ABI are deprecated
41+
//[current_feature]~^^ WARN `extern` declarations without an explicit ABI are deprecated
42+
//[future]~^^^ WARN `extern` declarations without an explicit ABI are deprecated
43+
//[future_feature]~^^^^ ERROR `extern` declarations without an explicit ABI are disallowed
44+
45+
fn main() {}

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