[clang][Interp] Handle std::move etc. builtins

Author: tbaederr

clang/lib/AST/Interp/InterpBuiltin.cpp

@@ -138,6 +138,7 @@ static bool retPrimValue(InterpState &S, CodePtr OpPC, APValue &Result,
   case X:                                                                      \
     return Ret<X>(S, OpPC, Result);
   switch (*T) {
+    RET_CASE(PT_Ptr);
     RET_CASE(PT_Float);
     RET_CASE(PT_Bool);
     RET_CASE(PT_Sint8);
@@ -533,6 +534,15 @@ static bool interp__builtin_classify_type(InterpState &S, CodePtr OpPC,
   return true;
 }
 
+static bool interp__builtin_move(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 Func->getDecl()->isConstexpr();
+}
+
 bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
                       const CallExpr *Call) {
   InterpFrame *Frame = S.Current;
@@ -702,6 +712,14 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,
       return false;
     break;
 
+  case Builtin::BIas_const:
+  case Builtin::BIforward:
+  case Builtin::BIforward_like:
+  case Builtin::BImove:
+    if (!interp__builtin_move(S, OpPC, Frame, F, Call))
+      return false;
+    break;
+
   default:
     return false;
   }

clang/test/AST/Interp/functions.cpp

@@ -378,3 +378,18 @@ namespace Packs {
   static_assert(foo<int, char>() == 2, "");
   static_assert(foo<>() == 0, "");
 }
+
+namespace std {
+template <typename T> struct remove_reference { using type = T; };
+template <typename T> struct remove_reference<T &> { using type = T; };
+template <typename T> struct remove_reference<T &&> { using type = T; };
+template <typename T>
+constexpr typename std::remove_reference<T>::type&& move(T &&t) noexcept {
+  return static_cast<typename std::remove_reference<T>::type &&>(t);
+}
+}
+/// The std::move declaration above gets translated to a builtin function.
+namespace Move {
+  constexpr int A = std::move(5);
+  static_assert(A == 5, "");
+}