Improve spans of malformed attribute errors

JonathanBrouwer · JonathanBrouwer · commit 17649b51dfc8 · 2025-12-13T15:43:17.000+01:00
diff --git a/compiler/rustc_attr_parsing/src/attributes/cfg.rs b/compiler/rustc_attr_parsing/src/attributes/cfg.rs
@@ -42,7 +42,7 @@ pub fn parse_cfg<S: Stage>(
     args: &ArgParser,
 ) -> Option<CfgEntry> {
     let ArgParser::List(list) = args else {
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return None;
     };
     let Some(single) = list.single() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
@@ -25,7 +25,7 @@ impl<S: Stage> SingleAttributeParser<S> for OptimizeParser {
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
         let Some(list) = args.list() else {
-            cx.expected_list(cx.attr_span);
+            cx.expected_list(cx.attr_span, args);
             return None;
         };
 
@@ -478,7 +478,7 @@ fn parse_tf_attribute<S: Stage>(
 ) -> impl IntoIterator<Item = (Symbol, Span)> {
     let mut features = Vec::new();
     let ArgParser::List(list) = args else {
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return features;
     };
     if list.is_empty() {
@@ -601,7 +601,7 @@ impl<S: Stage> SingleAttributeParser<S> for SanitizeParser {
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
         let Some(list) = args.list() else {
-            cx.expected_list(cx.attr_span);
+            cx.expected_list(cx.attr_span, args);
             return None;
         };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/confusables.rs b/compiler/rustc_attr_parsing/src/attributes/confusables.rs
@@ -13,7 +13,7 @@ impl<S: Stage> AttributeParser<S> for ConfusablesParser {
         template!(List: &[r#""name1", "name2", ..."#]),
         |this, cx, args| {
             let Some(list) = args.list() else {
-                cx.expected_list(cx.attr_span);
+                cx.expected_list(cx.attr_span, args);
                 return;
             };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/debugger.rs b/compiler/rustc_attr_parsing/src/attributes/debugger.rs
@@ -21,7 +21,7 @@ impl<S: Stage> CombineAttributeParser<S> for DebuggerViualizerParser {
         args: &ArgParser,
     ) -> impl IntoIterator<Item = Self::Item> {
         let Some(l) = args.list() else {
-            cx.expected_list(args.span().unwrap_or(cx.attr_span));
+            cx.expected_list(cx.attr_span, args);
             return None;
         };
         let Some(single) = l.single() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/doc.rs b/compiler/rustc_attr_parsing/src/attributes/doc.rs
@@ -106,7 +106,7 @@ impl DocParser {
             }
             Some(sym::attr) => {
                 let Some(list) = args.list() else {
-                    cx.expected_list(cx.attr_span);
+                    cx.expected_list(cx.attr_span, args);
                     return;
                 };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
@@ -76,7 +76,7 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {
                 return None;
             }
             _ => {
-                cx.expected_list(cx.attr_span);
+                cx.expected_list(cx.attr_span, args);
                 return None;
             }
         };
@@ -379,7 +379,7 @@ impl LinkParser {
             return true;
         }
         let Some(link_cfg) = item.args().list() else {
-            cx.expected_list(item.span());
+            cx.expected_list(item.span(), item.args());
             return true;
         };
         let Some(link_cfg) = link_cfg.single() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs
@@ -99,8 +99,8 @@ impl<S: Stage> AttributeParser<S> for MacroUseParser {
                         }
                     }
                 }
-                ArgParser::NameValue(_) => {
-                    cx.expected_list_or_no_args(span);
+                ArgParser::NameValue(nv) => {
+                    cx.expected_list_or_no_args(nv.args_span());
                 }
             }
         },
@@ -155,8 +155,8 @@ impl<S: Stage> SingleAttributeParser<S> for MacroExportParser {
                     }
                 }
             }
-            ArgParser::NameValue(_) => {
-                cx.expected_list_or_no_args(cx.attr_span);
+            ArgParser::NameValue(nv) => {
+                cx.expected_list_or_no_args(nv.args_span());
                 return None;
             }
         };
diff --git a/compiler/rustc_attr_parsing/src/attributes/must_use.rs b/compiler/rustc_attr_parsing/src/attributes/must_use.rs
@@ -41,8 +41,8 @@ impl<S: Stage> SingleAttributeParser<S> for MustUseParser {
                     };
                     Some(value_str)
                 }
-                ArgParser::List(_) => {
-                    cx.expected_name_value(cx.attr_span, None);
+                ArgParser::List(list) => {
+                    cx.expected_nv_or_no_args(list.span);
                     return None;
                 }
             },
diff --git a/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs
@@ -65,7 +65,7 @@ fn parse_derive_like<S: Stage>(
         if args.no_args().is_ok() && !trait_name_mandatory {
             return Some((None, ThinVec::new()));
         }
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return None;
     };
     let mut items = list.mixed();
@@ -96,15 +96,15 @@ fn parse_derive_like<S: Stage>(
     let mut attributes = ThinVec::new();
     if let Some(attrs) = items.next() {
         let Some(attr_list) = attrs.meta_item() else {
-            cx.expected_list(attrs.span());
+            cx.unexpected_literal(attrs.span());
             return None;
         };
         if !attr_list.path().word_is(sym::attributes) {
             cx.expected_specific_argument(attrs.span(), &[sym::attributes]);
             return None;
         }
         let Some(attr_list) = attr_list.args().list() else {
-            cx.expected_list(attrs.span());
+            cx.expected_list(attrs.span(), attr_list.args());
             return None;
         };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/prototype.rs b/compiler/rustc_attr_parsing/src/attributes/prototype.rs
@@ -27,7 +27,7 @@ impl<S: Stage> SingleAttributeParser<S> for CustomMirParser {
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) -> Option<AttributeKind> {
         let Some(list) = args.list() else {
-            cx.expected_list(cx.attr_span);
+            cx.expected_list(cx.attr_span, args);
             return None;
         };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/repr.rs b/compiler/rustc_attr_parsing/src/attributes/repr.rs
@@ -33,7 +33,7 @@ impl<S: Stage> CombineAttributeParser<S> for ReprParser {
         let mut reprs = Vec::new();
 
         let Some(list) = args.list() else {
-            cx.expected_list(cx.attr_span);
+            cx.expected_list(cx.attr_span, args);
             return reprs;
         };
 
@@ -278,7 +278,7 @@ impl AlignParser {
     fn parse<S: Stage>(&mut self, cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser) {
         match args {
             ArgParser::NoArgs | ArgParser::NameValue(_) => {
-                cx.expected_list(cx.attr_span);
+                cx.expected_list(cx.attr_span, args);
             }
             ArgParser::List(list) => {
                 let Some(align) = list.single() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/stability.rs b/compiler/rustc_attr_parsing/src/attributes/stability.rs
@@ -295,7 +295,7 @@ pub(crate) fn parse_stability<S: Stage>(
     let mut since = None;
 
     let ArgParser::List(list) = args else {
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return None;
     };
 
@@ -367,7 +367,7 @@ pub(crate) fn parse_unstability<S: Stage>(
     let mut old_name = None;
 
     let ArgParser::List(list) = args else {
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return None;
     };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/traits.rs b/compiler/rustc_attr_parsing/src/attributes/traits.rs
@@ -22,7 +22,7 @@ impl<S: Stage> SingleAttributeParser<S> for SkipDuringMethodDispatchParser {
         let mut array = false;
         let mut boxed_slice = false;
         let Some(args) = args.list() else {
-            cx.expected_list(cx.attr_span);
+            cx.expected_list(cx.attr_span, args);
             return None;
         };
         if args.is_empty() {
diff --git a/compiler/rustc_attr_parsing/src/attributes/util.rs b/compiler/rustc_attr_parsing/src/attributes/util.rs
@@ -43,7 +43,7 @@ pub(crate) fn parse_single_integer<S: Stage>(
     args: &ArgParser,
 ) -> Option<u128> {
     let Some(list) = args.list() else {
-        cx.expected_list(cx.attr_span);
+        cx.expected_list(cx.attr_span, args);
         return None;
     };
     let Some(single) = list.single() else {
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
@@ -464,14 +464,23 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         self.emit_parse_error(span, AttributeParseErrorReason::ExpectedIntegerLiteral)
     }
 
-    pub(crate) fn expected_list(&self, span: Span) -> ErrorGuaranteed {
+    pub(crate) fn expected_list(&self, span: Span, args: &ArgParser) -> ErrorGuaranteed {
+        let span = match args {
+            ArgParser::NoArgs => span,
+            ArgParser::List(list) => list.span,
+            ArgParser::NameValue(nv) => nv.args_span(),
+        };
         self.emit_parse_error(span, AttributeParseErrorReason::ExpectedList)
     }
 
     pub(crate) fn expected_list_or_no_args(&self, span: Span) -> ErrorGuaranteed {
         self.emit_parse_error(span, AttributeParseErrorReason::ExpectedListOrNoArgs)
     }
 
+    pub(crate) fn expected_nv_or_no_args(&self, span: Span) -> ErrorGuaranteed {
+        self.emit_parse_error(span, AttributeParseErrorReason::ExpectedNameValueOrNoArgs)
+    }
+
     pub(crate) fn expected_no_args(&self, span: Span) -> ErrorGuaranteed {
         self.emit_parse_error(span, AttributeParseErrorReason::ExpectedNoArgs)
     }
diff --git a/compiler/rustc_attr_parsing/src/parser.rs b/compiler/rustc_attr_parsing/src/parser.rs
@@ -177,7 +177,7 @@ impl ArgParser {
         match self {
             Self::NoArgs => Ok(()),
             Self::List(args) => Err(args.span),
-            Self::NameValue(args) => Err(args.eq_span.to(args.value_span)),
+            Self::NameValue(args) => Err(args.args_span()),
         }
     }
 }
@@ -314,6 +314,10 @@ impl NameValueParser {
     pub fn value_as_str(&self) -> Option<Symbol> {
         self.value_as_lit().kind.str()
     }
+
+    pub fn args_span(&self) -> Span {
+        self.eq_span.to(self.value_span)
+    }
 }
 
 fn expr_to_lit(
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -511,6 +511,7 @@ pub(crate) enum AttributeParseErrorReason<'a> {
     ExpectedSingleArgument,
     ExpectedList,
     ExpectedListOrNoArgs,
+    ExpectedNameValueOrNoArgs,
     UnexpectedLiteral,
     ExpectedNameValue(Option<Symbol>),
     DuplicateKey(Symbol),
@@ -586,6 +587,9 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError<'_> {
             AttributeParseErrorReason::ExpectedListOrNoArgs => {
                 diag.span_label(self.span, "expected a list or no arguments here");
             }
+            AttributeParseErrorReason::ExpectedNameValueOrNoArgs => {
+                diag.span_label(self.span, "didn't expect a list here");
+            }
             AttributeParseErrorReason::DuplicateKey(key) => {
                 diag.span_label(self.span, format!("found `{key}` used as a key more than once"));
                 diag.code(E0538);
diff --git a/tests/ui/attributes/invalid-macro-use.stderr b/tests/ui/attributes/invalid-macro-use.stderr
@@ -14,7 +14,9 @@ error[E0539]: malformed `macro_use` attribute input
   --> $DIR/invalid-macro-use.rs:4:1
    |
 LL | #[macro_use = 5]
-   | ^^^^^^^^^^^^^^^^ expected a list or no arguments here
+   | ^^^^^^^^^^^^---^
+   |             |
+   |             expected a list or no arguments here
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute>
 help: try changing it to one of the following valid forms of the attribute
diff --git a/tests/ui/attributes/malformed-attrs.stderr b/tests/ui/attributes/malformed-attrs.stderr
@@ -318,7 +318,9 @@ error[E0539]: malformed `must_use` attribute input
   --> $DIR/malformed-attrs.rs:61:1
    |
 LL | #[must_use()]
-   | ^^^^^^^^^^^^^
+   | ^^^^^^^^^^--^
+   |           |
+   |           didn't expect a list here
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute>
 help: try changing it to one of the following valid forms of the attribute
@@ -628,7 +630,9 @@ error[E0539]: malformed `macro_use` attribute input
   --> $DIR/malformed-attrs.rs:216:1
    |
 LL | #[macro_use = 1]
-   | ^^^^^^^^^^^^^^^^ expected a list or no arguments here
+   | ^^^^^^^^^^^^---^
+   |             |
+   |             expected a list or no arguments here
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute>
 help: try changing it to one of the following valid forms of the attribute
@@ -644,7 +648,9 @@ error[E0539]: malformed `macro_export` attribute input
   --> $DIR/malformed-attrs.rs:221:1
    |
 LL | #[macro_export = 18]
-   | ^^^^^^^^^^^^^^^^^^^^ expected a list or no arguments here
+   | ^^^^^^^^^^^^^^^----^
+   |                |
+   |                expected a list or no arguments here
    |
 help: try changing it to one of the following valid forms of the attribute
    |
diff --git a/tests/ui/attributes/malformed-fn-align.stderr b/tests/ui/attributes/malformed-fn-align.stderr
@@ -20,9 +20,9 @@ error[E0539]: malformed `rustc_align` attribute input
   --> $DIR/malformed-fn-align.rs:17:1
    |
 LL | #[rustc_align = 16]
-   | ^^^^^^^^^^^^^^^^^^^
-   | |
-   | expected this to be a list
+   | ^^^^^^^^^^^^^^----^
+   | |             |
+   | |             expected this to be a list
    | help: must be of the form: `#[rustc_align(<alignment in bytes>)]`
 
 error[E0589]: invalid alignment value: not an unsuffixed integer
diff --git a/tests/ui/attributes/malformed-must_use.stderr b/tests/ui/attributes/malformed-must_use.stderr
@@ -2,7 +2,9 @@ error[E0539]: malformed `must_use` attribute input
   --> $DIR/malformed-must_use.rs:1:1
    |
 LL | #[must_use()]
-   | ^^^^^^^^^^^^^
+   | ^^^^^^^^^^--^
+   |           |
+   |           didn't expect a list here
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute>
 help: try changing it to one of the following valid forms of the attribute
diff --git a/tests/ui/attributes/malformed-static-align.stderr b/tests/ui/attributes/malformed-static-align.stderr
@@ -2,9 +2,9 @@ error[E0539]: malformed `rustc_align_static` attribute input
   --> $DIR/malformed-static-align.rs:4:1
    |
 LL | #[rustc_align_static = 16]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
-   | |
-   | expected this to be a list
+   | ^^^^^^^^^^^^^^^^^^^^^----^
+   | |                    |
+   | |                    expected this to be a list
    | help: must be of the form: `#[rustc_align_static(<alignment in bytes>)]`
 
 error[E0589]: invalid alignment value: not an unsuffixed integer
diff --git a/tests/ui/attributes/rustc_skip_during_method_dispatch.stderr b/tests/ui/attributes/rustc_skip_during_method_dispatch.stderr
@@ -11,9 +11,9 @@ error[E0539]: malformed `rustc_skip_during_method_dispatch` attribute input
   --> $DIR/rustc_skip_during_method_dispatch.rs:7:1
    |
 LL | #[rustc_skip_during_method_dispatch = "array"]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   | |
-   | expected this to be a list
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---------^
+   | |                                   |
+   | |                                   expected this to be a list
    | help: must be of the form: `#[rustc_skip_during_method_dispatch(array, boxed_slice)]`
 
 error[E0539]: malformed `rustc_skip_during_method_dispatch` attribute input
diff --git a/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr b/tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr
@@ -13,9 +13,9 @@ error[E0539]: malformed `cfg` attribute input
   --> $DIR/cfg-attr-syntax-validation.rs:7:1
    |
 LL | #[cfg = 10]
-   | ^^^^^^^^^^^
-   | |
-   | expected this to be a list
+   | ^^^^^^----^
+   | |     |
+   | |     expected this to be a list
    | help: must be of the form: `#[cfg(predicate)]`
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute>
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-macro_use.stderr b/tests/ui/feature-gates/issue-43106-gating-of-macro_use.stderr
@@ -20,7 +20,9 @@ error[E0539]: malformed `macro_use` attribute input
   --> $DIR/issue-43106-gating-of-macro_use.rs:15:5
    |
 LL |     #[macro_use = "2700"] struct S;
-   |     ^^^^^^^^^^^^^^^^^^^^^ expected a list or no arguments here
+   |     ^^^^^^^^^^^^--------^
+   |                 |
+   |                 expected a list or no arguments here
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute>
 help: try changing it to one of the following valid forms of the attribute
diff --git a/tests/ui/link-native-libs/link-attr-validation-early.stderr b/tests/ui/link-native-libs/link-attr-validation-early.stderr
@@ -10,7 +10,9 @@ error[E0539]: malformed `link` attribute input
   --> $DIR/link-attr-validation-early.rs:3:1
    |
 LL | #[link = "foo"]
-   | ^^^^^^^^^^^^^^^ expected this to be a list
+   | ^^^^^^^-------^
+   |        |
+   |        expected this to be a list
    |
    = note: for more information, visit <https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute>
 
diff --git a/tests/ui/link-native-libs/link-attr-validation-late.stderr b/tests/ui/link-native-libs/link-attr-validation-late.stderr
diff --git a/tests/ui/malformed/malformed-regressions.stderr b/tests/ui/malformed/malformed-regressions.stderr
diff --git a/tests/ui/proc-macro/attribute.stderr b/tests/ui/proc-macro/attribute.stderr
diff --git a/tests/ui/repr/repr.stderr b/tests/ui/repr/repr.stderr
diff --git a/tests/ui/sanitize-attr/invalid-sanitize.stderr b/tests/ui/sanitize-attr/invalid-sanitize.stderr
diff --git a/tests/ui/stability-attribute/stability-attribute-sanity-4.stderr b/tests/ui/stability-attribute/stability-attribute-sanity-4.stderr
diff --git a/tests/ui/target-feature/invalid-attribute.stderr b/tests/ui/target-feature/invalid-attribute.stderr

Original file line number	Diff line number	Diff line change
`@@ -106,7 +106,7 @@ impl DocParser {`
`106`	`106`	`}`
`107`	`107`	`Some(sym::attr) => {`
`108`	`108`	`let Some(list) = args.list() else {`
`109`		`- cx.expected_list(cx.attr_span);`
	`109`	`+ cx.expected_list(cx.attr_span, args);`
`110`	`110`	`return;`
`111`	`111`	`};`
`112`	`112`
Original file line number	Diff line number	Diff line change
`@@ -76,7 +76,7 @@ impl<S: Stage> CombineAttributeParser<S> for LinkParser {`
`76`	`76`	`return None;`
`77`	`77`	`}`
`78`	`78`	`_ => {`
`79`		`- cx.expected_list(cx.attr_span);`
	`79`	`+ cx.expected_list(cx.attr_span, args);`
`80`	`80`	`return None;`
`81`	`81`	`}`
`82`	`82`	`};`
`@@ -379,7 +379,7 @@ impl LinkParser {`
`379`	`379`	`return true;`
`380`	`380`	`}`
`381`	`381`	`let Some(link_cfg) = item.args().list() else {`
`382`		`- cx.expected_list(item.span());`
	`382`	`+ cx.expected_list(item.span(), item.args());`
`383`	`383`	`return true;`
`384`	`384`	`};`
`385`	`385`	`let Some(link_cfg) = link_cfg.single() else {`
Original file line number	Diff line number	Diff line change
`@@ -99,8 +99,8 @@ impl<S: Stage> AttributeParser<S> for MacroUseParser {`
`99`	`99`	`}`
`100`	`100`	`}`
`101`	`101`	`}`
`102`		`- ArgParser::NameValue(_) => {`
`103`		`- cx.expected_list_or_no_args(span);`
	`102`	`+ ArgParser::NameValue(nv) => {`
	`103`	`+ cx.expected_list_or_no_args(nv.args_span());`
`104`	`104`	`}`
`105`	`105`	`}`
`106`	`106`	`},`
`@@ -155,8 +155,8 @@ impl<S: Stage> SingleAttributeParser<S> for MacroExportParser {`
`155`	`155`	`}`
`156`	`156`	`}`
`157`	`157`	`}`
`158`		`- ArgParser::NameValue(_) => {`
`159`		`- cx.expected_list_or_no_args(cx.attr_span);`
	`158`	`+ ArgParser::NameValue(nv) => {`
	`159`	`+ cx.expected_list_or_no_args(nv.args_span());`
`160`	`160`	`return None;`
`161`	`161`	`}`
`162`	`162`	`};`
Original file line number	Diff line number	Diff line change
`@@ -41,8 +41,8 @@ impl<S: Stage> SingleAttributeParser<S> for MustUseParser {`
`41`	`41`	`};`
`42`	`42`	`Some(value_str)`
`43`	`43`	`}`
`44`		`- ArgParser::List(_) => {`
`45`		`- cx.expected_name_value(cx.attr_span, None);`
	`44`	`+ ArgParser::List(list) => {`
	`45`	`+ cx.expected_nv_or_no_args(list.span);`
`46`	`46`	`return None;`
`47`	`47`	`}`
`48`	`48`	`},`