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Make #[link="dl"] an FCW rather than an error #147262

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Merged
bors merged 2 commits into from
Oct 5, 2025
Merged

Make #[link="dl"] an FCW rather than an error #147262

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5c95f8b
Add failing regression test for #[link="dl"]
JonathanBrouwer Oct 2, 2025
1c85a1d
Make `#[link="dl"]` a warning rather than an error
JonathanBrouwer Oct 2, 2025
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29 changes: 20 additions & 9 deletions compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -65,10 +65,22 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
cx: &'c mut AcceptContext<'_, '_, S>,
args: &'c ArgParser<'_>,
) -> impl IntoIterator<Item = Self::Item> + 'c {
let mut result = None;
let Some(items) = args.list() else {
cx.expected_list(cx.attr_span);
return result;
let items = match args {
ArgParser::List(list) => list,
// This is an edgecase added because making this a hard error would break too many crates
// Specifically `#[link = "dl"]` is accepted with a FCW
// For more information, see https://github.com/rust-lang/rust/pull/143193
ArgParser::NameValue(nv) if nv.value_as_str().is_some_and(|v| v == sym::dl) => {
let suggestions = <Self as CombineAttributeParser<S>>::TEMPLATE
.suggestions(cx.attr_style, "link");
let span = cx.attr_span;
cx.emit_lint(AttributeLintKind::IllFormedAttributeInput { suggestions }, span);
return None;
}
_ => {
cx.expected_list(cx.attr_span);
return None;
}
};

let sess = cx.sess();
Expand Down Expand Up @@ -113,7 +125,7 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
}
};
if !cont {
return result;
return None;
}
}

Expand Down Expand Up @@ -202,7 +214,7 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
}
let Some((name, name_span)) = name else {
cx.emit_err(LinkRequiresName { span: cx.attr_span });
return result;
return None;
};

// Do this outside of the loop so that `import_name_type` can be specified before `kind`.
Expand All @@ -218,15 +230,14 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
cx.emit_err(RawDylibNoNul { span: name_span });
}

result = Some(LinkEntry {
Some(LinkEntry {
span: cx.attr_span,
kind: kind.unwrap_or(NativeLibKind::Unspecified),
name,
cfg,
verbatim,
import_name_type,
});
result
})
}
}

Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_span/src/symbol.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -873,6 +873,7 @@ symbols! {
div,
div_assign,
diverging_block_default,
dl,
do_not_recommend,
doc,
doc_alias,
Expand Down
10 changes: 10 additions & 0 deletions tests/ui/attributes/link-dl.allowed.stderr
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@@ -0,0 +1,10 @@
Future incompatibility report: Future breakage diagnostic:
warning: valid forms for the attribute are `#[link(name = "...")]`, `#[link(name = "...", import_name_type = "decorated|noprefix|undecorated")]`, `#[link(name = "...", kind = "dylib|static|...")]`, `#[link(name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated")]`, and `#[link(name = "...", wasm_import_module = "...")]`
--> $DIR/link-dl.rs:14:1
|
LL | #[link="dl"]
| ^^^^^^^^^^^^
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>

23 changes: 23 additions & 0 deletions tests/ui/attributes/link-dl.default_fcw.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
error: valid forms for the attribute are `#[link(name = "...")]`, `#[link(name = "...", import_name_type = "decorated|noprefix|undecorated")]`, `#[link(name = "...", kind = "dylib|static|...")]`, `#[link(name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated")]`, and `#[link(name = "...", wasm_import_module = "...")]`
--> $DIR/link-dl.rs:14:1
|
LL | #[link="dl"]
| ^^^^^^^^^^^^
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
= note: `#[deny(ill_formed_attribute_input)]` (part of `#[deny(future_incompatible)]`) on by default

error: aborting due to 1 previous error

Future incompatibility report: Future breakage diagnostic:
error: valid forms for the attribute are `#[link(name = "...")]`, `#[link(name = "...", import_name_type = "decorated|noprefix|undecorated")]`, `#[link(name = "...", kind = "dylib|static|...")]`, `#[link(name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated")]`, and `#[link(name = "...", wasm_import_module = "...")]`
--> $DIR/link-dl.rs:14:1
|
LL | #[link="dl"]
| ^^^^^^^^^^^^
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
= note: `#[deny(ill_formed_attribute_input)]` (part of `#[deny(future_incompatible)]`) on by default

19 changes: 19 additions & 0 deletions tests/ui/attributes/link-dl.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
// Regression test for an issue discovered in https://github.com/rust-lang/rust/pull/143193/files and rediscovered in https://github.com/rust-lang/rust/issues/147254#event-20049906781
// Malformed #[link] attribute was supposed to be deny-by-default report-in-deps FCW,
// but accidentally was landed as a hard error.
//
// revision `default_fcw` tests that with `ill_formed_attribute_input` (the default) denied,
// the attribute produces an FCW
// revision `allowed` tests that with `ill_formed_attribute_input` allowed the test passes

//@ revisions: default_fcw allowed
//@[allowed] check-pass

#[cfg_attr(allowed, allow(ill_formed_attribute_input))]

#[link="dl"]
//[default_fcw]~^ ERROR valid forms for the attribute are
//[default_fcw]~| WARN previously accepted
extern "C" { }

fn main() {}
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