[clang] [Clang][Sema] Fix type of enumerators in incomplete enumerations (PR #84068)

[via cfe-commits]

https://github.com/Kupa-Martin created https://github.com/llvm/llvm-project/pull/84068

Enumerators dont have the type of their enumeration before the closing brace. In these cases Expr::getEnumCoercedType() incorrectly returned the enumeration type.

Introduced in PR #81418

>From bc9f93713a07643aa3095a7d6d402d1202e07b9e Mon Sep 17 00:00:00 2001
From: 44-2-Kupa-Martin <kupamartinclassroom at gmail.com>
Date: Tue, 5 Mar 2024 17:21:02 -0300
Subject: [PATCH] [Clang][Sema] Fix type of enumerators in incomplete
 enumerations Enumerators dont have the type of their enumeration before the
 closing brace. In these cases Expr::getEnumCoercedType() incorrectly returned
 the enumeration type.

Introduced in PR #81418
---
 clang/lib/AST/Expr.cpp                             | 9 ++++++---
 clang/test/Sema/warn-compare-enum-types-mismatch.c | 4 +++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index b4de2155adcebd..9a28e6f750069b 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -264,10 +264,13 @@ namespace {
 }
 
 QualType Expr::getEnumCoercedType(const ASTContext &Ctx) const {
-  if (isa<EnumType>(this->getType()))
+  if (isa<EnumType>(this->getType())) {
     return this->getType();
-  else if (const auto *ECD = this->getEnumConstantDecl())
-    return Ctx.getTypeDeclType(cast<EnumDecl>(ECD->getDeclContext()));
+  } else if (const auto *ECD = this->getEnumConstantDecl()) {
+    const auto *ED = cast<EnumDecl>(ECD->getDeclContext());
+    if (ED->isCompleteDefinition())
+      return Ctx.getTypeDeclType(ED);
+  }
   return this->getType();
 }
 
diff --git a/clang/test/Sema/warn-compare-enum-types-mismatch.c b/clang/test/Sema/warn-compare-enum-types-mismatch.c
index 2b72aae16b977a..1094a6972e778d 100644
--- a/clang/test/Sema/warn-compare-enum-types-mismatch.c
+++ b/clang/test/Sema/warn-compare-enum-types-mismatch.c
@@ -6,7 +6,9 @@ typedef enum EnumA {
 } EnumA;
 
 enum EnumB {
-  B
+  B,
+  B1 = 1,
+  B2 = A == B1
 };
 
 enum {