1 files changed, 22 insertions, 31 deletions
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
index 9f2ac5112..e405462bb 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
@@ -372,45 +372,36 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                 }
             }
             (Meta::Path(_), "subdiagnostic") => {
-                return Ok(quote! { #diag.subdiagnostic(#binding); });
-            }
-            (Meta::NameValue(_), "subdiagnostic") => {
-                throw_invalid_attr!(attr, &meta, |diag| {
-                    diag.help("`eager` is the only supported nested attribute for `subdiagnostic`")
-                })
+                if FieldInnerTy::from_type(&info.binding.ast().ty).will_iterate() {
+                    let DiagnosticDeriveKind::Diagnostic { handler } = &self.parent.kind else {
+                        // No eager translation for lints.
+                        return Ok(quote! { #diag.subdiagnostic(#binding); });
+                    };
+                    return Ok(quote! { #diag.eager_subdiagnostic(#handler, #binding); });
+                } else {
+                    return Ok(quote! { #diag.subdiagnostic(#binding); });
+                }
             }
             (Meta::List(MetaList { ref nested, .. }), "subdiagnostic") => {
-                if nested.len() != 1 {
+                if nested.len() == 1
+                    && let Some(NestedMeta::Meta(Meta::Path(path))) = nested.first()
+                    && path.is_ident("eager") {
+                        let handler = match &self.parent.kind {
+                            DiagnosticDeriveKind::Diagnostic { handler } => handler,
+                            DiagnosticDeriveKind::LintDiagnostic => {
+                                throw_invalid_attr!(attr, &meta, |diag| {
+                                    diag.help("eager subdiagnostics are not supported on lints")
+                                })
+                            }
+                        };
+                        return Ok(quote! { #diag.eager_subdiagnostic(#handler, #binding); });
+                } else {
                     throw_invalid_attr!(attr, &meta, |diag| {
                         diag.help(
                             "`eager` is the only supported nested attribute for `subdiagnostic`",
                         )
                     })
                 }
-
-                let handler = match &self.parent.kind {
-                    DiagnosticDeriveKind::Diagnostic { handler } => handler,
-                    DiagnosticDeriveKind::LintDiagnostic => {
-                        throw_invalid_attr!(attr, &meta, |diag| {
-                            diag.help("eager subdiagnostics are not supported on lints")
-                        })
-                    }
-                };
-
-                let nested_attr = nested.first().expect("pop failed for single element list");
-                match nested_attr {
-                    NestedMeta::Meta(meta @ Meta::Path(_))
-                        if meta.path().segments.last().unwrap().ident.to_string().as_str()
-                            == "eager" =>
-                    {
-                        return Ok(quote! { #diag.eager_subdiagnostic(#handler, #binding); });
-                    }
-                    _ => {
-                        throw_invalid_nested_attr!(attr, nested_attr, |diag| {
-                            diag.help("`eager` is the only supported nested attribute for `subdiagnostic`")
-                        })
-                    }
-                }
             }
             _ => (),
         }