address comments

compiler/rustc_macros/src/diagnostics/utils.rs

@@ -420,16 +420,11 @@ pub(super) enum AllowMultipleAlternatives {
     Yes,
 }
 
-/// Constructs the `format!()` invocation(s) necessary for a `#[suggestion*(code = "foo")]` or
+fn parse_suggestion_values(
-/// `#[suggestion*(code("foo", "bar"))]` attribute field
-pub(super) fn build_suggestion_code(
-    code_field: &Ident,
     nested: ParseNestedMeta<'_>,
-    fields: &impl HasFieldMap,
     allow_multiple: AllowMultipleAlternatives,
-) -> TokenStream {
+) -> syn::Result<Vec<LitStr>> {
-    let values = match (|| {
+    let values = if let Ok(val) = nested.value() {
-        let values: Vec<LitStr> = if let Ok(val) = nested.value() {
         vec![val.parse()?]
     } else {
         let content;
@@ -468,7 +463,17 @@ pub(super) fn build_suggestion_code(
     };
 
     Ok(values)
-    })() {
+}
+
+/// Constructs the `format!()` invocation(s) necessary for a `#[suggestion*(code = "foo")]` or
+/// `#[suggestion*(code("foo", "bar"))]` attribute field
+pub(super) fn build_suggestion_code(
+    code_field: &Ident,
+    nested: ParseNestedMeta<'_>,
+    fields: &impl HasFieldMap,
+    allow_multiple: AllowMultipleAlternatives,
+) -> TokenStream {
+    let values = match parse_suggestion_values(nested, allow_multiple) {
         Ok(x) => x,
         Err(e) => return e.into_compile_error(),
     };
@@ -706,14 +711,14 @@ impl SubdiagnosticKind {
             let path_span = nested.path.span().unwrap();
             let val_span = nested.input.span().unwrap();
 
-            macro get_string() {
+            macro_rules! get_string {
-                {
+                () => {{
                     let Ok(value) = nested.value().and_then(|x| x.parse::<LitStr>()) else {
                         span_err(val_span, "expected `= \"xxx\"`").emit();
                         return Ok(());
                     };
                     value
-                }
+                }};
             }
 
             let mut has_errors = false;