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EthiraricEthiraric
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Add a lint for duplicated attributes.
1 parent 753e569 commit 2be94d4

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8 files changed

+134
-4
lines changed

8 files changed

+134
-4
lines changed

‎Cargo.lock

+1
Original file line numberDiff line numberDiff line change
@@ -3678,6 +3678,7 @@ dependencies = [
36783678
"rustc_expand",
36793679
"rustc_feature",
36803680
"rustc_lexer",
3681+
"rustc_lint_defs",
36813682
"rustc_parse",
36823683
"rustc_parse_format",
36833684
"rustc_session",

‎compiler/rustc_builtin_macros/Cargo.toml

+1
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
1515
rustc_errors = { path = "../rustc_errors" }
1616
rustc_feature = { path = "../rustc_feature" }
1717
rustc_lexer = { path = "../rustc_lexer" }
18+
rustc_lint_defs = { path = "../rustc_lint_defs" }
1819
rustc_parse = { path = "../rustc_parse" }
1920
rustc_target = { path = "../rustc_target" }
2021
rustc_session = { path = "../rustc_session" }

‎compiler/rustc_builtin_macros/src/cfg_eval.rs

+2-1
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
use crate::util::check_builtin_macro_attribute;
1+
use crate::util::{check_builtin_macro_attribute, warn_on_duplicate_attribute};
22

33
use rustc_ast as ast;
44
use rustc_ast::mut_visit::MutVisitor;
@@ -25,6 +25,7 @@ crate fn expand(
2525
annotatable: Annotatable,
2626
) -> Vec<Annotatable> {
2727
check_builtin_macro_attribute(ecx, meta_item, sym::cfg_eval);
28+
warn_on_duplicate_attribute(&ecx, &annotatable, sym::cfg_eval);
2829
vec![cfg_eval(ecx.sess, ecx.ecfg.features, annotatable)]
2930
}
3031

‎compiler/rustc_builtin_macros/src/test.rs

+4-1
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
/// The expansion from a test function to the appropriate test struct for libtest
22
/// Ideally, this code would be in libtest but for efficiency and error messages it lives here.
3-
use crate::util::check_builtin_macro_attribute;
3+
use crate::util::{check_builtin_macro_attribute, warn_on_duplicate_attribute};
44

55
use rustc_ast as ast;
66
use rustc_ast::attr;
@@ -27,6 +27,7 @@ pub fn expand_test_case(
2727
anno_item: Annotatable,
2828
) -> Vec<Annotatable> {
2929
check_builtin_macro_attribute(ecx, meta_item, sym::test_case);
30+
warn_on_duplicate_attribute(&ecx, &anno_item, sym::test_case);
3031

3132
if !ecx.ecfg.should_test {
3233
return vec![];
@@ -55,6 +56,7 @@ pub fn expand_test(
5556
item: Annotatable,
5657
) -> Vec<Annotatable> {
5758
check_builtin_macro_attribute(cx, meta_item, sym::test);
59+
warn_on_duplicate_attribute(&cx, &item, sym::test);
5860
expand_test_or_bench(cx, attr_sp, item, false)
5961
}
6062

@@ -65,6 +67,7 @@ pub fn expand_bench(
6567
item: Annotatable,
6668
) -> Vec<Annotatable> {
6769
check_builtin_macro_attribute(cx, meta_item, sym::bench);
70+
warn_on_duplicate_attribute(&cx, &item, sym::bench);
6871
expand_test_or_bench(cx, attr_sp, item, true)
6972
}
7073

‎compiler/rustc_builtin_macros/src/util.rs

+33-2
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
1-
use rustc_ast::MetaItem;
2-
use rustc_expand::base::ExtCtxt;
1+
use rustc_ast::{Attribute, MetaItem};
2+
use rustc_expand::base::{Annotatable, ExtCtxt};
33
use rustc_feature::AttributeTemplate;
4+
use rustc_lint_defs::builtin::DUPLICATE_MACRO_ATTRIBUTES;
45
use rustc_parse::validate_attr;
56
use rustc_span::Symbol;
67

@@ -10,3 +11,33 @@ pub fn check_builtin_macro_attribute(ecx: &ExtCtxt<'_>, meta_item: &MetaItem, na
1011
let attr = ecx.attribute(meta_item.clone());
1112
validate_attr::check_builtin_attribute(&ecx.sess.parse_sess, &attr, name, template);
1213
}
14+
15+
/// Emit a warning if the item is annotated with the given attribute. This is used to diagnose when
16+
/// an attribute may have been mistakenly duplicated.
17+
pub fn warn_on_duplicate_attribute(ecx: &ExtCtxt<'_>, item: &Annotatable, name: Symbol) {
18+
let attrs: Option<&[Attribute]> = match item {
19+
Annotatable::Item(item) => Some(&item.attrs),
20+
Annotatable::TraitItem(item) => Some(&item.attrs),
21+
Annotatable::ImplItem(item) => Some(&item.attrs),
22+
Annotatable::ForeignItem(item) => Some(&item.attrs),
23+
Annotatable::Expr(expr) => Some(&expr.attrs),
24+
Annotatable::Arm(arm) => Some(&arm.attrs),
25+
Annotatable::ExprField(field) => Some(&field.attrs),
26+
Annotatable::PatField(field) => Some(&field.attrs),
27+
Annotatable::GenericParam(param) => Some(&param.attrs),
28+
Annotatable::Param(param) => Some(&param.attrs),
29+
Annotatable::FieldDef(def) => Some(&def.attrs),
30+
Annotatable::Variant(variant) => Some(&variant.attrs),
31+
_ => None,
32+
};
33+
if let Some(attrs) = attrs {
34+
if let Some(attr) = ecx.sess.find_by_name(attrs, name) {
35+
ecx.parse_sess().buffer_lint(
36+
DUPLICATE_MACRO_ATTRIBUTES,
37+
attr.span,
38+
ecx.current_expansion.lint_node_id,
39+
"duplicated attribute",
40+
);
41+
}
42+
}
43+
}

‎compiler/rustc_lint_defs/src/builtin.rs

+30
Original file line numberDiff line numberDiff line change
@@ -3092,6 +3092,7 @@ declare_lint_pass! {
30923092
TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
30933093
DEREF_INTO_DYN_SUPERTRAIT,
30943094
DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
3095+
DUPLICATE_MACRO_ATTRIBUTES,
30953096
]
30963097
}
30973098

@@ -3629,3 +3630,32 @@ declare_lint! {
36293630
reference: "issue #89460 <https://github.com/rust-lang/rust/issues/89460>",
36303631
};
36313632
}
3633+
3634+
declare_lint! {
3635+
/// The `duplicate_macro_attributes` lint detects when a `#[test]`-like built-in macro
3636+
/// attribute is duplicated on an item. This lint may trigger on `bench`, `cfg_eval`, `test`
3637+
/// and `test_case`.
3638+
///
3639+
/// ### Example
3640+
///
3641+
/// ```rust,ignore (needs --test)
3642+
/// #[test]
3643+
/// #[test]
3644+
/// fn foo() {}
3645+
/// ```
3646+
///
3647+
/// {{produces}}
3648+
///
3649+
/// ### Explanation
3650+
///
3651+
/// A duplicated attribute may erroneously originate from a copy-paste and the effect of it
3652+
/// being duplicated may not be obvious or desireable.
3653+
///
3654+
/// For instance, doubling the `#[test]` attributes registers the test to be run twice with no
3655+
/// change to its environment.
3656+
///
3657+
/// [issue #90979]: https://github.com/rust-lang/rust/issues/90979
3658+
pub DUPLICATE_MACRO_ATTRIBUTES,
3659+
Warn,
3660+
"duplicated attribute"
3661+
}

‎src/test/ui/attributes/duplicated-attributes.rs

+41
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,41 @@
1+
// Test that, if an item is annotated with a builtin attribute more than once, a warning is
2+
// emitted.
3+
// Tests https://github.com/rust-lang/rust/issues/90979
4+
5+
// check-pass
6+
// compile-flags: --test
7+
8+
#![feature(test)]
9+
#![feature(cfg_eval)]
10+
11+
#[test]
12+
#[test]
13+
//~^ WARNING duplicated attribute
14+
fn f() {}
15+
16+
// The following shouldn't trigger an error. The attribute is not duplicated.
17+
#[test]
18+
fn f2() {}
19+
20+
// The following shouldn't trigger an error either. The second attribute is not #[test].
21+
#[test]
22+
#[inline]
23+
fn f3() {}
24+
25+
extern crate test;
26+
use test::Bencher;
27+
28+
#[bench]
29+
#[bench]
30+
//~^ WARNING duplicated attribute
31+
fn f4(_: &mut Bencher) {}
32+
33+
#[cfg_eval]
34+
#[cfg_eval]
35+
//~^ WARNING duplicated attribute
36+
struct S;
37+
38+
#[cfg_eval]
39+
struct S2;
40+
41+
fn main() {}

‎src/test/ui/attributes/duplicated-attributes.stderr

+22
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
1+
warning: duplicated attribute
2+
--> $DIR/duplicated-attributes.rs:12:1
3+
|
4+
LL | #[test]
5+
| ^^^^^^^
6+
|
7+
= note: `#[warn(duplicate_macro_attributes)]` on by default
8+
9+
warning: duplicated attribute
10+
--> $DIR/duplicated-attributes.rs:29:1
11+
|
12+
LL | #[bench]
13+
| ^^^^^^^^
14+
15+
warning: duplicated attribute
16+
--> $DIR/duplicated-attributes.rs:34:1
17+
|
18+
LL | #[cfg_eval]
19+
| ^^^^^^^^^^^
20+
21+
warning: 3 warnings emitted
22+

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