feat: allow multiple suggestions for malformed crate_type attribute

Author: Blindspot22

compiler/rustc_builtin_macros/src/cfg_accessible.rs

@@ -44,7 +44,8 @@ impl MultiItemModifier for Expander {
         item: Annotatable,
         _is_derive_const: bool,
     ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
-        let template = AttributeTemplate { list: Some("path"), ..Default::default() };
+        let template = AttributeTemplate { list: Some(&["path"]), ..Default::default() };
+
         validate_attr::check_builtin_meta_item(
             &ecx.sess.psess,
             meta_item,

compiler/rustc_builtin_macros/src/derive.rs

@@ -34,8 +34,10 @@ impl MultiItemModifier for Expander {
         let (sess, features) = (ecx.sess, ecx.ecfg.features);
         let result =
             ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| {
-                let template =
-                    AttributeTemplate { list: Some("Trait1, Trait2, ..."), ..Default::default() };
+                let template = AttributeTemplate {
+                    list: Some(&["Trait1", "Trait2", "..."]),
+                    ..Default::default()
+                };
                 validate_attr::check_builtin_meta_item(
                     &sess.psess,
                     meta_item,

compiler/rustc_feature/src/builtin_attrs.rs

@@ -248,7 +248,8 @@ fn emit_malformed_attribute(
         suggestions.push(format!("#{inner}[{name}]"));
     }
     if let Some(descr) = template.list {
-        suggestions.push(format!("#{inner}[{name}({descr})]"));
+        let descr_formatted = descr.join(", ");
+        suggestions.push(format!("#{inner}[{name}({descr_formatted})]"));
     }
     suggestions.extend(template.one_of.iter().map(|&word| format!("#{inner}[{name}({word})]")));
     if let Some(descr) = template.name_value_str {

compiler/rustc_parse/src/validate_attr.rs

@@ -23,7 +23,7 @@ pub struct BuiltinAttribute {
 #[derive(Clone, Copy)]
 pub struct AttributeTemplate {
     pub word: bool,
-    pub list: Option<&'static str>,
+    pub list: Option<&'static [&'static str]>,
     pub name_value_str: Option<&'static str>,
 }