give a better error for tuple structs in derive(Diagnostic)

rust-lang · Dec 24, 2023 · df9d457 · df9d457
1 parent 74583db
commit df9d457
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
@@ -263,7 +263,10 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
         let mut field_binding = binding_info.binding.clone();
         field_binding.set_span(field.ty.span());
 
-        let ident = field.ident.as_ref().unwrap();
+        let Some(ident) = field.ident.as_ref() else {
+            span_err(field.span().unwrap(), "tuple structs are not supported").emit();
+            return TokenStream::new();
+        };
         let ident = format_ident!("{}", ident); // strip `r#` prefix, if present
 
         quote! {

diff --git a/compiler/rustc_macros/src/diagnostics/error.rs b/compiler/rustc_macros/src/diagnostics/error.rs
@@ -55,7 +55,7 @@ fn path_to_string(path: &syn::Path) -> String {
 /// Returns an error diagnostic on span `span` with msg `msg`.
 #[must_use]
 pub(crate) fn span_err<T: Into<String>>(span: impl MultiSpan, msg: T) -> Diagnostic {
-    Diagnostic::spanned(span, Level::Error, msg)
+    Diagnostic::spanned(span, Level::Error, format!("derive(Diagnostic): {}", msg.into()))
 }
 
 /// Emit a diagnostic on span `$span` with msg `$msg` (optionally performing additional decoration