Ensure #[suggestion] is only applied to correct tuple types

compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs

@@ -571,46 +571,37 @@ impl DiagnosticDeriveBuilder {
                 let mut span_idx = None;
                 let mut applicability_idx = None;
 
+                fn type_err(span: &Span) -> Result<!, DiagnosticDeriveError> {
+                    span_err(span.unwrap(), "wrong types for suggestion")
+                        .help(
+                            "`#[suggestion(...)]` on a tuple field must be applied to fields \
+                             of type `(Span, Applicability)`",
+                        )
+                        .emit();
+                    Err(DiagnosticDeriveError::ErrorHandled)
+                }
+
                 for (idx, elem) in tup.elems.iter().enumerate() {
                     if type_matches_path(elem, &["rustc_span", "Span"]) {
-                        if span_idx.is_none() {
+                        span_idx.set_once((syn::Index::from(idx), elem.span().unwrap()));
-                            span_idx = Some(syn::Index::from(idx));
-                        } else {
-                            throw_span_err!(
-                                info.span.unwrap(),
-                                "type of field annotated with `#[suggestion(...)]` contains more \
-                                 than one `Span`"
-                            );
-                        }
                     } else if type_matches_path(elem, &["rustc_errors", "Applicability"]) {
-                        if applicability_idx.is_none() {
+                        applicability_idx.set_once((syn::Index::from(idx), elem.span().unwrap()));
-                            applicability_idx = Some(syn::Index::from(idx));
+                    } else {
-                        } else {
+                        type_err(&elem.span())?;
-                            throw_span_err!(
-                                info.span.unwrap(),
-                                "type of field annotated with `#[suggestion(...)]` contains more \
-                                 than one Applicability"
-                            );
-                        }
                     }
                 }
 
-                if let Some(span_idx) = span_idx {
+                let Some((span_idx, _)) = span_idx else {
-                    let binding = &info.binding.binding;
+                    type_err(&tup.span())?;
-                    let span = quote!(#binding.#span_idx);
+                };
-                    let applicability = applicability_idx
+                let Some((applicability_idx, _applicability_span)) = applicability_idx else {
-                        .map(|applicability_idx| quote!(#binding.#applicability_idx))
+                    type_err(&tup.span())?;
-                        .unwrap_or_else(|| quote!(rustc_errors::Applicability::Unspecified));
+                };
+                let binding = &info.binding.binding;
+                let span = quote!(#binding.#span_idx);
+                let applicability = quote!(#binding.#applicability_idx);
 
-                    return Ok((span, Some(applicability)));
+                Ok((span, Some(applicability)))
-                }
-
-                throw_span_err!(info.span.unwrap(), "wrong types for suggestion", |diag| {
-                    diag.help(
-                        "`#[suggestion(...)]` on a tuple field must be applied to fields of type \
-                         `(Span, Applicability)`",
-                    )
-                });
             }
             // If `ty` isn't a `Span` or `(Span, Applicability)` then emit an error.
             _ => throw_span_err!(info.span.unwrap(), "wrong field type for suggestion", |diag| {

src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs

@@ -269,16 +269,16 @@ struct SuggestWithSpanOnly {
 #[diag(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithDuplicateSpanAndApplicability {
     #[suggestion(typeck::suggestion, code = "This is suggested code")]
-    //~^ ERROR type of field annotated with `#[suggestion(...)]` contains more than one `Span`
     suggestion: (Span, Span, Applicability),
+    //~^ ERROR specified multiple times
 }
 
 #[derive(Diagnostic)]
 #[diag(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithDuplicateApplicabilityAndSpan {
     #[suggestion(typeck::suggestion, code = "This is suggested code")]
-    //~^ ERROR type of field annotated with `#[suggestion(...)]` contains more than one
     suggestion: (Applicability, Applicability, Span),
+    //~^ ERROR specified multiple times
 }
 
 #[derive(Diagnostic)]
@@ -589,3 +589,19 @@ struct DuplicatedSuggestionCode {
     //~^ ERROR specified multiple times
     suggestion: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(typeck::ambiguous_lifetime_bound, code = "E0123")]
+struct InvalidTypeInSuggestionTuple {
+    #[suggestion(typeck::suggestion, code = "...")]
+    suggestion: (Span, usize),
+    //~^ ERROR wrong types for suggestion
+}
+
+#[derive(Diagnostic)]
+#[diag(typeck::ambiguous_lifetime_bound, code = "E0123")]
+struct MissingApplicabilityInSuggestionTuple {
+    #[suggestion(typeck::suggestion, code = "...")]
+    suggestion: (Span,),
+    //~^ ERROR wrong types for suggestion
+}

src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr

@@ -263,21 +263,29 @@ LL | |     suggestion: Applicability,
    |
    = help: `#[suggestion(...)]` should be applied to fields of type `Span` or `(Span, Applicability)`
 
-error: type of field annotated with `#[suggestion(...)]` contains more than one `Span`
+error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:271:5
+  --> $DIR/diagnostic-derive.rs:272:24
    |
-LL | /     #[suggestion(typeck::suggestion, code = "This is suggested code")]
+LL |     suggestion: (Span, Span, Applicability),
-LL | |
+   |                        ^^^^
-LL | |     suggestion: (Span, Span, Applicability),
+   |
-   | |___________________________________________^
+note: previously specified here
+  --> $DIR/diagnostic-derive.rs:272:18
+   |
+LL |     suggestion: (Span, Span, Applicability),
+   |                  ^^^^
 
-error: type of field annotated with `#[suggestion(...)]` contains more than one Applicability
+error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:279:5
+  --> $DIR/diagnostic-derive.rs:280:33
    |
-LL | /     #[suggestion(typeck::suggestion, code = "This is suggested code")]
+LL |     suggestion: (Applicability, Applicability, Span),
-LL | |
+   |                                 ^^^^^^^^^^^^^
-LL | |     suggestion: (Applicability, Applicability, Span),
+   |
-   | |____________________________________________________^
+note: previously specified here
+  --> $DIR/diagnostic-derive.rs:280:18
+   |
+LL |     suggestion: (Applicability, Applicability, Span),
+   |                  ^^^^^^^^^^^^^
 
 error: `#[label = ...]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:287:5
@@ -415,6 +423,22 @@ note: previously specified here
 LL |     #[suggestion(typeck::suggestion, code = "...", code = ",,,")]
    |                                      ^^^^^^^^^^^^
 
+error: wrong types for suggestion
+  --> $DIR/diagnostic-derive.rs:597:24
+   |
+LL |     suggestion: (Span, usize),
+   |                        ^^^^^
+   |
+   = help: `#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`
+
+error: wrong types for suggestion
+  --> $DIR/diagnostic-derive.rs:605:17
+   |
+LL |     suggestion: (Span,),
+   |                 ^^^^^^^
+   |
+   = help: `#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`
+
 error: cannot find attribute `nonsense` in this scope
   --> $DIR/diagnostic-derive.rs:53:3
    |
@@ -471,7 +495,7 @@ LL |         arg: impl IntoDiagnosticArg,
    |                   ^^^^^^^^^^^^^^^^^ required by this bound in `DiagnosticBuilder::<'a, G>::set_arg`
    = note: this error originates in the derive macro `Diagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 56 previous errors
+error: aborting due to 58 previous errors
 
 Some errors have detailed explanations: E0277, E0425.
 For more information about an error, try `rustc --explain E0277`.