[clang][Interp] Fix Descriptor::getElemQualType() for complex/vectors

We handle them like arrays but still need to differentiate between
array/vector/complex types when dealing with QualTypes.

Author: tbaederr

clang/lib/AST/Interp/Descriptor.cpp

@@ -359,8 +359,14 @@ QualType Descriptor::getType() const {
 
 QualType Descriptor::getElemQualType() const {
   assert(isArray());
-  const auto *AT = cast<ArrayType>(getType());
-  return AT->getElementType();
+  QualType T = getType();
+  if (const auto *AT = T->getAsArrayTypeUnsafe())
+    return AT->getElementType();
+  if (const auto *CT = T->getAs<ComplexType>())
+    return CT->getElementType();
+  if (const auto *CT = T->getAs<VectorType>())
+    return CT->getElementType();
+  llvm_unreachable("Array that's not an array/complex/vector type?");
 }
 
 SourceLocation Descriptor::getLocation() const {

clang/test/AST/Interp/vectors.cpp

@@ -81,3 +81,13 @@ namespace VectorElementExpr {
   static_assert(twoElts.x == 22, ""); // ref-error {{not an integral constant expression}}
   static_assert(twoElts.y == 33, ""); // ref-error {{not an integral constant expression}}
 }
+
+namespace Temporaries {
+  typedef __attribute__((vector_size(16))) int vi4a;
+  typedef __attribute__((ext_vector_type(4))) int vi4b;
+  struct S {
+    vi4a v;
+    vi4b w;
+  };
+  int &&s = S().w[1];
+}