[clang][Interp] Implement __builtin___{CF,NS}StringMakeConstantString

By doing the same thing the current interpreter does: Just passing on
the first parameter.

Author: tbaederr

clang/lib/AST/Interp/InterpBuiltin.cpp

@@ -606,10 +606,9 @@ static bool interp__builtin_eh_return_data_regno(InterpState &S, CodePtr OpPC,
   return true;
 }
 
-static bool interp__builtin_launder(InterpState &S, CodePtr OpPC,
-                                    const InterpFrame *Frame,
-                                    const Function *Func,
-                                    const CallExpr *Call) {
+/// Just takes the first Argument to the call and puts it on the stack.
+static bool noopPointer(InterpState &S, CodePtr OpPC, const InterpFrame *Frame,
+                        const Function *Func, const CallExpr *Call) {
   const Pointer &Arg = S.Stk.peek<Pointer>();
   S.Stk.push<Pointer>(Arg);
   return true;
@@ -1144,7 +1143,9 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
     break;
 
   case Builtin::BI__builtin_launder:
-    if (!interp__builtin_launder(S, OpPC, Frame, F, Call))
+  case Builtin::BI__builtin___CFStringMakeConstantString:
+  case Builtin::BI__builtin___NSStringMakeConstantString:
+    if (!noopPointer(S, OpPC, Frame, F, Call))
       return false;
     break;
 

clang/test/AST/Interp/builtin-functions.cpp

@@ -510,3 +510,12 @@ namespace bswap {
   int h4 = __builtin_bswap32(0x1234) == 0x34120000 ? 1 : f();
   int h5 = __builtin_bswap64(0x1234) == 0x3412000000000000 ? 1 : f();
 }
+
+#define CFSTR __builtin___CFStringMakeConstantString
+void test7(void) {
+  const void *X;
+  X = CFSTR("\242"); // both-warning {{input conversion stopped}}
+  X = CFSTR("\0"); // no-warning
+  X = CFSTR(242); // both-error {{cannot initialize a parameter of type 'const char *' with an rvalue of type 'int'}}
+  X = CFSTR("foo", "bar"); // both-error {{too many arguments to function call}}
+}