[clang][Interp] Protect InitPtr from non-initializable pointers

This can happen when an initializer returns a dummy pointer.

Author: tbaederr

clang/lib/AST/Interp/Interp.h

@@ -1278,13 +1278,16 @@ inline bool GetPtrThisBase(InterpState &S, CodePtr OpPC, uint32_t Off) {
 
 inline bool InitPtrPop(InterpState &S, CodePtr OpPC) {
   const Pointer &Ptr = S.Stk.pop<Pointer>();
-  Ptr.initialize();
+  if (Ptr.canBeInitialized())
+    Ptr.initialize();
   return true;
 }
 
 inline bool InitPtr(InterpState &S, CodePtr OpPC) {
   const Pointer &Ptr = S.Stk.peek<Pointer>();
-  Ptr.initialize();
+
+  if (Ptr.canBeInitialized())
+    Ptr.initialize();
   return true;
 }
 

clang/test/AST/Interp/complex.c

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify=expected,both -Wno-unused-value %s
+// RUN: %clang_cc1 -verify=ref,both -Wno-unused-value %s
+
+// expected-no-diagnostics
+// ref-no-diagnostics
+
+void blah() {
+  __complex__ unsigned xx;
+  __complex__ signed yy;
+  __complex__ int result;
+
+  /// The following line calls into the constant interpreter.
+  result = xx * yy;
+}