[clang] [CIR] Upstream enum support (PR #136807)

[Ankur Ahir via cfe-commits]

================
@@ -399,6 +399,14 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
     break;
   }
 
+  case Type::Enum: {
+    const EnumDecl *ED = cast<EnumType>(ty)->getDecl();
+    if (ED->isCompleteDefinition() || ED->isFixed())
+      return convertType(ED->getIntegerType());
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Ankur-0429 wrote:

There is a function [UpdateCompletedType](https://github.com/llvm/clangir/blob/a9eac21b2f5bcfa4169bde20faca769f70a06f28/clang/lib/CIR/CodeGen/CIRGenTypes.cpp#L830) that currently does not exist in this repo. Is this something that should be added? Wasn't too sure how much the fork diverged from the currently llvm repo.

https://github.com/llvm/llvm-project/pull/136807