[clang][Interp] Reject non-pointer typed dummies

This happens a lot for NonTypeTemplateParm decls.

Author: tbaederr

clang/lib/AST/Interp/Compiler.cpp

@@ -5094,9 +5094,10 @@ bool Compiler<Emitter>::visitDeclRef(const ValueDecl *D, const Expr *E) {
     if (E->getType()->isVoidType())
       return true;
     // Convert the dummy pointer to another pointer type if we have to.
-    if (PrimType PT = classifyPrim(E); PT != PT_Ptr && isPtrType(PT)) {
-      if (!this->emitDecayPtr(PT_Ptr, PT, E))
-        return false;
+    if (PrimType PT = classifyPrim(E); PT != PT_Ptr) {
+      if (isPtrType(PT))
+        return this->emitDecayPtr(PT_Ptr, PT, E);
+      return false;
     }
     return true;
   }

clang/test/AST/Interp/literals.cpp

@@ -1276,3 +1276,17 @@ namespace ComparisonAgainstOnePastEnd {
 
   static_assert(&a + 1 == &b + 1, ""); // both-error {{static assertion failed}}
 };
+
+namespace NTTP {
+  template <typename _Tp, unsigned _Nm>
+    constexpr unsigned
+    size(const _Tp (&)[_Nm]) noexcept
+    { return _Nm; }
+
+  template <char C>
+  static int write_padding() {
+    static const char Chars[] = {C};
+
+    return size(Chars);
+  }
+}