[clang] [Sema] Decay functions/array to pointers in `IncompatiblePointerDiscardsQualifiers` and `IncompatibleOBTKinds` cases (PR #187038)

[Aaron Ballman via cfe-commits]

================
@@ -17705,6 +17706,12 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   case AssignConvertType::CompatibleOBTDiscards:
     return false;
   case AssignConvertType::IncompatibleOBTKinds: {
+    assert(!SrcType->isFunctionType() &&
+           "Unexpected function type found in IncompatibleOBTKinds assignment");
+    if (SrcType->canDecayToPointerType()) {
+      SrcType = Context.getDecayedType(SrcType);
+    }
----------------
AaronBallman wrote:

```suggestion
    if (SrcType->canDecayToPointerType())
      SrcType = Context.getDecayedType(SrcType);
```

https://github.com/llvm/llvm-project/pull/187038