Rollup merge of rust-lang#149917 - GuillaumeGomez:malformed-attribute-suggestions, r=JonathanBrouwer

If there are too many suggestions for malformed attribute, do not suggest them

Part of rust-lang#149865.

This not only covers for doc attributes but for all attributes, so don't hesitate to tell me if you want it to be limited to only doc attributes (although I think it's actually a nice improvement overall).

Also, I picked 3 as the maximum number of suggestions before it becomes noise, but it's very much open to debate.

r? `@JonathanBrouwer`

Author: GuillaumeGomez

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -709,16 +709,20 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError<'_> {
             diag.note(format!("for more information, visit <{link}>"));
         }
 
-        diag.span_suggestions(
-            self.attr_span,
-            if self.suggestions.len() == 1 {
-                "must be of the form".to_string()
-            } else {
-                format!("try changing it to one of the following valid forms of the {description}")
-            },
-            self.suggestions,
-            Applicability::HasPlaceholders,
-        );
+        if self.suggestions.len() < 4 {
+            diag.span_suggestions(
+                self.attr_span,
+                if self.suggestions.len() == 1 {
+                    "must be of the form".to_string()
+                } else {
+                    format!(
+                        "try changing it to one of the following valid forms of the {description}"
+                    )
+                },
+                self.suggestions,
+                Applicability::HasPlaceholders,
+            );
+        }
 
         diag
     }

compiler/rustc_attr_parsing/src/validate_attr.rs

@@ -198,6 +198,11 @@ fn emit_malformed_attribute(
             suggestions.push(format!("#{inner}[{name} = \"{descr}\"]"));
         }
     }
+    // If there are too many suggestions, better remove all of them as it's just noise at this
+    // point.
+    if suggestions.len() > 3 {
+        suggestions.clear();
+    }
     if should_warn(name) {
         psess.buffer_lint(
             ILL_FORMED_ATTRIBUTE_INPUT,

tests/rustdoc-ui/bad-render-options.stderr

@@ -5,22 +5,6 @@ LL | #![doc(html_favicon_url)]
    | ^^^^^^^----------------^^
    |        |
    |        expected this to be of the form `html_favicon_url = "..."`
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_favicon_url)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_favicon_url)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_favicon_url)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_favicon_url)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 21 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:6:1
@@ -29,22 +13,6 @@ LL | #![doc(html_logo_url)]
    | ^^^^^^^-------------^^
    |        |
    |        expected this to be of the form `html_logo_url = "..."`
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_logo_url)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_logo_url)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_logo_url)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_logo_url)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 21 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:9:1
@@ -53,22 +21,6 @@ LL | #![doc(html_playground_url)]
    | ^^^^^^^-------------------^^
    |        |
    |        expected this to be of the form `html_playground_url = "..."`
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_playground_url)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_playground_url)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_playground_url)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_playground_url)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 21 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:12:1
@@ -77,22 +29,6 @@ LL | #![doc(issue_tracker_base_url)]
    | ^^^^^^^----------------------^^
    |        |
    |        expected this to be of the form `issue_tracker_base_url = "..."`
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(issue_tracker_base_url)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(issue_tracker_base_url)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(issue_tracker_base_url)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(issue_tracker_base_url)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 21 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:15:1
@@ -101,22 +37,6 @@ LL | #![doc(html_favicon_url = 1)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^-^^
    |                           |
    |                           expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_favicon_url = 1)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_favicon_url = 1)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_favicon_url = 1)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_favicon_url = 1)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:18:1
@@ -125,22 +45,6 @@ LL | #![doc(html_logo_url = 2)]
    | ^^^^^^^^^^^^^^^^^^^^^^^-^^
    |                        |
    |                        expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_logo_url = 2)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_logo_url = 2)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_logo_url = 2)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_logo_url = 2)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:21:1
@@ -149,22 +53,6 @@ LL | #![doc(html_playground_url = 3)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-^^
    |                              |
    |                              expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_playground_url = 3)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_playground_url = 3)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_playground_url = 3)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_playground_url = 3)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error[E0539]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:24:1
@@ -173,22 +61,6 @@ LL | #![doc(issue_tracker_base_url = 4)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-^^
    |                                 |
    |                                 expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(issue_tracker_base_url = 4)]
-LL + #![doc = "string"]
-   |
-LL - #![doc(issue_tracker_base_url = 4)]
-LL + #![doc(alias)]
-   |
-LL - #![doc(issue_tracker_base_url = 4)]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(issue_tracker_base_url = 4)]
-LL + #![doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error[E0565]: malformed `doc` attribute input
   --> $DIR/bad-render-options.rs:27:1
@@ -197,22 +69,6 @@ LL | #![doc(html_no_source = "asdf")]
    | ^^^^^^^^^^^^^^^^^^^^^^--------^^
    |                       |
    |                       didn't expect any arguments here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #![doc(html_no_source = "asdf")]
-LL + #![doc = "string"]
-   |
-LL - #![doc(html_no_source = "asdf")]
-LL + #![doc(alias)]
-   |
-LL - #![doc(html_no_source = "asdf")]
-LL + #![doc(attribute)]
-   |
-LL - #![doc(html_no_source = "asdf")]
-LL + #![doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error: aborting due to 9 previous errors
 

tests/rustdoc-ui/check-doc-alias-attr.stderr

@@ -11,22 +11,6 @@ LL | #[doc(alias = 0)]
    | ^^^^^^^^^^^^^^-^^
    |               |
    |               expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #[doc(alias = 0)]
-LL + #[doc = "string"]
-   |
-LL - #[doc(alias = 0)]
-LL + #[doc(alias)]
-   |
-LL - #[doc(alias = 0)]
-LL + #[doc(attribute)]
-   |
-LL - #[doc(alias = 0)]
-LL + #[doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error: '"' character isn't allowed in `#[doc(alias = "...")]`
   --> $DIR/check-doc-alias-attr.rs:9:15
@@ -79,22 +63,6 @@ LL | #[doc(alias(0))]
    | ^^^^^^^^^^^^-^^^
    |             |
    |             expected a string literal here
-   |
-help: try changing it to one of the following valid forms of the attribute
-   |
-LL - #[doc(alias(0))]
-LL + #[doc = "string"]
-   |
-LL - #[doc(alias(0))]
-LL + #[doc(alias)]
-   |
-LL - #[doc(alias(0))]
-LL + #[doc(attribute)]
-   |
-LL - #[doc(alias(0))]
-LL + #[doc(auto_cfg)]
-   |
-   = and 22 other candidates
 
 error: '"' character isn't allowed in `#[doc(alias = "...")]`
   --> $DIR/check-doc-alias-attr.rs:20:13