Check for redef enumerators in define_enum (#285)

Signed-off-by: acassagnes <acassagnes@bloomberg.net>

Author: zebullax

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -3271,6 +3271,9 @@ def p3385_sema_trace_execution_checkpoint : Warning<
 def p3385_warn_unsupported_attribute : Error<
   "reflecting over the unsupported '%0' attribute is ill-formed">;
 
+// P4033
+def p4033_sema_define_enum_enumerator : Error<"could not create enumerator %0">;
+
 // C++11 char16_t/char32_t
 def warn_cxx98_compat_unicode_type : Warning<
   "'%0' type specifier is incompatible with C++98">,
@@ -12611,7 +12614,7 @@ def warn_zero_as_null_pointer_constant : Warning<
   InGroup<DiagGroup<"zero-as-null-pointer-constant">>, DefaultIgnore;
 
 def warn_not_eliding_copy_on_return : Warning<
-  "not eliding copy on return">, 
+  "not eliding copy on return">,
   InGroup<DiagGroup<"nrvo">>, DefaultIgnore;
 
 def err_nullability_cs_multilevel : Error<

clang/lib/AST/ExprConstantMeta.cpp

@@ -5867,6 +5867,9 @@ bool define_enum(APValue &Result, ASTContext &C, MetaActions &Meta,
   EnumDecl *completedEnum =
       Meta.DefineEnum(foundDecl, EnumSpecs, ContainingDecl,
                                 TargetEnum, nullptr, Args[0]->getExprLoc());
+  if (!completedEnum) {
+    return true;
+  }
   return SetAndSucceed(Result, makeReflection(completedEnum));
 }
 

clang/lib/Sema/SemaReflect.cpp

@@ -529,6 +529,11 @@ class MetaActionsImpl : public MetaActions {
       Decl *EnumConstDecl =
           S.ActOnEnumConstant(&EnumScope, ED, LastEnumConstDecl, DefinitionLoc,
                               II, attrs, DefinitionLoc, Val);
+      if (!EnumConstDecl) {
+        // TODO any rollback we need to do ?...
+        S.Diag(DefinitionLoc, diag::p4033_sema_define_enum_enumerator) << enumSpec->name;
+        return nullptr;
+      }
 
       // Attach annotations as CXX26AnnotationAttr directly on the decl.
       for (APValue *annotVal : enumSpec->annotations) {