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Use cfg_attr_trace in AST with a placeholder attribute for accurate suggestion #133823

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Merged
merged 1 commit into from
May 30, 2025
Merged

Use cfg_attr_trace in AST with a placeholder attribute for accurate suggestion #133823

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3 changes: 2 additions & 1 deletion compiler/rustc_lint/messages.ftl
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Expand Up @@ -953,7 +953,8 @@ lint_unused_doc_comment = unused doc comment
.help = to document an item produced by a macro, the macro must produce the documentation as part of its expansion

lint_unused_extern_crate = unused extern crate
.suggestion = remove it
.label = unused
.suggestion = remove the unused `extern crate`

lint_unused_import_braces = braces around {$node} is unnecessary

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4 changes: 2 additions & 2 deletions compiler/rustc_lint/src/early/diagnostics.rs
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Expand Up @@ -292,8 +292,8 @@ pub(super) fn decorate_lint(
BuiltinLintDiag::ByteSliceInPackedStructWithDerive { ty } => {
lints::ByteSliceInPackedStructWithDerive { ty }.decorate_lint(diag);
}
BuiltinLintDiag::UnusedExternCrate { removal_span } => {
lints::UnusedExternCrate { removal_span }.decorate_lint(diag);
BuiltinLintDiag::UnusedExternCrate { span, removal_span } => {
lints::UnusedExternCrate { span, removal_span }.decorate_lint(diag);
}
BuiltinLintDiag::ExternCrateNotIdiomatic { vis_span, ident_span } => {
let suggestion_span = vis_span.between(ident_span);
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4 changes: 3 additions & 1 deletion compiler/rustc_lint/src/lints.rs
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Expand Up @@ -3051,7 +3051,9 @@ pub(crate) struct ByteSliceInPackedStructWithDerive {
#[derive(LintDiagnostic)]
#[diag(lint_unused_extern_crate)]
pub(crate) struct UnusedExternCrate {
#[suggestion(code = "", applicability = "machine-applicable")]
#[label]
pub span: Span,
#[suggestion(code = "", applicability = "machine-applicable", style = "verbose")]
pub removal_span: Span,
}

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1 change: 1 addition & 0 deletions compiler/rustc_lint_defs/src/lib.rs
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Expand Up @@ -736,6 +736,7 @@ pub enum BuiltinLintDiag {
ty: String,
},
UnusedExternCrate {
span: Span,
removal_span: Span,
},
ExternCrateNotIdiomatic {
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1 change: 1 addition & 0 deletions compiler/rustc_resolve/src/check_unused.rs
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Expand Up @@ -154,6 +154,7 @@ impl<'a, 'ra, 'tcx> UnusedImportCheckVisitor<'a, 'ra, 'tcx> {
extern_crate.id,
span,
BuiltinLintDiag::UnusedExternCrate {
span: extern_crate.span,
removal_span: extern_crate.span_with_attributes,
},
);
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6 changes: 5 additions & 1 deletion tests/ui/editions/edition-extern-crate-allowed.stderr
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Expand Up @@ -2,14 +2,18 @@ warning: unused extern crate
--> $DIR/edition-extern-crate-allowed.rs:7:1
|
LL | extern crate edition_extern_crate_allowed;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/edition-extern-crate-allowed.rs:5:9
|
LL | #![warn(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[warn(unused_extern_crates)]` implied by `#[warn(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - extern crate edition_extern_crate_allowed;
|

warning: 1 warning emitted

7 changes: 6 additions & 1 deletion tests/ui/imports/extern-crate-used.stderr
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Expand Up @@ -2,13 +2,18 @@ error: unused extern crate
--> $DIR/extern-crate-used.rs:18:1
|
LL | extern crate core;
| ^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/extern-crate-used.rs:6:9
|
LL | #![deny(unused_extern_crates)]
| ^^^^^^^^^^^^^^^^^^^^
help: remove the unused `extern crate`
|
LL - extern crate core;
LL +
|

error: aborting due to 1 previous error

41 changes: 35 additions & 6 deletions tests/ui/lint/unnecessary-extern-crate.stderr
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Expand Up @@ -2,43 +2,72 @@ error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:6:1
|
LL | extern crate core;
| ^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/unnecessary-extern-crate.rs:3:9
|
LL | #![deny(unused_extern_crates)]
| ^^^^^^^^^^^^^^^^^^^^
help: remove the unused `extern crate`
|
LL - extern crate core;
|

error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:9:1
|
LL | extern crate core as x;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate core as x;
|

error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:31:5
|
LL | extern crate core;
| ^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate core;
|

error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:35:5
|
LL | extern crate core as x;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate core as x;
|

error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:44:9
|
LL | extern crate core;
| ^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate core;
|

error: unused extern crate
--> $DIR/unnecessary-extern-crate.rs:48:9
|
LL | extern crate core as x;
| ^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate core as x;
|

error: aborting due to 6 previous errors

15 changes: 13 additions & 2 deletions tests/ui/lint/unused/lint-unused-extern-crate.stderr
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Expand Up @@ -2,19 +2,30 @@ error: unused extern crate
--> $DIR/lint-unused-extern-crate.rs:11:1
|
LL | extern crate lint_unused_extern_crate5;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/lint-unused-extern-crate.rs:7:9
|
LL | #![deny(unused_extern_crates)]
| ^^^^^^^^^^^^^^^^^^^^
help: remove the unused `extern crate`
|
LL - extern crate lint_unused_extern_crate5;
LL +
|

error: unused extern crate
--> $DIR/lint-unused-extern-crate.rs:29:5
|
LL | extern crate lint_unused_extern_crate2;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
help: remove the unused `extern crate`
|
LL - extern crate lint_unused_extern_crate2;
LL +
|

error: aborting due to 2 previous errors

6 changes: 5 additions & 1 deletion tests/ui/proc-macro/no-macro-use-attr.stderr
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Expand Up @@ -2,13 +2,17 @@ warning: unused extern crate
--> $DIR/no-macro-use-attr.rs:6:1
|
LL | extern crate test_macros;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/no-macro-use-attr.rs:4:9
|
LL | #![warn(unused_extern_crates)]
| ^^^^^^^^^^^^^^^^^^^^
help: remove the unused `extern crate`
|
LL - extern crate test_macros;
|

warning: 1 warning emitted

6 changes: 5 additions & 1 deletion tests/ui/rust-2018/extern-crate-idiomatic-in-2018.stderr
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Expand Up @@ -2,14 +2,18 @@ error: unused extern crate
--> $DIR/extern-crate-idiomatic-in-2018.rs:12:1
|
LL | extern crate edition_lint_paths;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/extern-crate-idiomatic-in-2018.rs:9:9
|
LL | #![deny(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[deny(unused_extern_crates)]` implied by `#[deny(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - extern crate edition_lint_paths;
|

error: aborting due to 1 previous error

2 changes: 1 addition & 1 deletion tests/ui/rust-2018/issue-54400-unused-extern-crate-attr-span.rs
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Expand Up @@ -8,7 +8,7 @@

// The suggestion span should include the attribute.

#[cfg(not(FALSE))] //~ HELP remove it
#[cfg(not(FALSE))] //~ HELP remove
extern crate edition_lint_paths;
//~^ ERROR unused extern crate

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12 changes: 7 additions & 5 deletions tests/ui/rust-2018/issue-54400-unused-extern-crate-attr-span.stderr
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@@ -1,18 +1,20 @@
error: unused extern crate
--> $DIR/issue-54400-unused-extern-crate-attr-span.rs:12:1
|
LL | / #[cfg(not(FALSE))]
LL | | extern crate edition_lint_paths;
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
| |________________________________|
| help: remove it
LL | extern crate edition_lint_paths;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/issue-54400-unused-extern-crate-attr-span.rs:6:9
|
LL | #![deny(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[deny(unused_extern_crates)]` implied by `#[deny(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - #[cfg(not(FALSE))]
LL - extern crate edition_lint_paths;
|

error: aborting due to 1 previous error

7 changes: 6 additions & 1 deletion tests/ui/rust-2018/remove-extern-crate.stderr
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Expand Up @@ -2,14 +2,19 @@ warning: unused extern crate
--> $DIR/remove-extern-crate.rs:11:1
|
LL | extern crate core;
| ^^^^^^^^^^^^^^^^^^ help: remove it
| ^^^^^^^^^^^^^^^^^^ unused
|
note: the lint level is defined here
--> $DIR/remove-extern-crate.rs:7:9
|
LL | #![warn(rust_2018_idioms)]
| ^^^^^^^^^^^^^^^^
= note: `#[warn(unused_extern_crates)]` implied by `#[warn(rust_2018_idioms)]`
help: remove the unused `extern crate`
|
LL - extern crate core;
LL +
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I thought this was a rendering bug, but it is because of the //~ removed comment.

|

warning: `extern crate` is not idiomatic in the new edition
--> $DIR/remove-extern-crate.rs:35:5
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15 changes: 15 additions & 0 deletions tests/ui/rust-2018/removing-extern-crate-malformed-cfg.fixed
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@@ -0,0 +1,15 @@
//@ edition:2018
//@ aux-build:../removing-extern-crate.rs
//@ run-rustfix

#![warn(rust_2018_idioms)]

//~ WARNING unused extern crate
//~ WARNING unused extern crate

mod another {
//~ WARNING unused extern crate
//~ WARNING unused extern crate
}

fn main() {}
17 changes: 17 additions & 0 deletions tests/ui/rust-2018/removing-extern-crate-malformed-cfg.rs
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@@ -0,0 +1,17 @@
//@ edition:2018
//@ aux-build:../removing-extern-crate.rs
//@ run-rustfix

#![warn(rust_2018_idioms)]

#[cfg_attr(test, "macro_use")] //~ ERROR expected
extern crate removing_extern_crate as foo; //~ WARNING unused extern crate
extern crate core; //~ WARNING unused extern crate

mod another {
#[cfg_attr(test)] //~ ERROR expected
extern crate removing_extern_crate as foo; //~ WARNING unused extern crate
extern crate core; //~ WARNING unused extern crate
}

fn main() {}
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