[PATCH] c++: implement __add_pointer built-in trait

[Ken Matsui via Gcc-patches]

This patch implements built-in trait for std::add_pointer.

gcc/cp/ChangeLog:

* cp-trait.def: Define __add_pointer.
* semantics.cc (finish_trait_type): Handle CPTK_ADD_POINTER.

gcc/testsuite/ChangeLog:

* g++.dg/ext/has-builtin-1.C: Test existence of __add_pointer.
* g++.dg/ext/add_pointer.C: New test.

---
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index bac593c0094..07fab8db26b 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -91,6 +91,7 @@ DEFTRAIT_TYPE (REMOVE_CV, "__remove_cv", 1)
 DEFTRAIT_TYPE (REMOVE_REFERENCE, "__remove_reference", 1)
 DEFTRAIT_TYPE (REMOVE_CVREF, "__remove_cvref", 1)
 DEFTRAIT_TYPE (UNDERLYING_TYPE,  "__underlying_type", 1)
+DEFTRAIT_TYPE (ADD_POINTER, "__add_pointer", 1)

 /* These traits yield a type pack, not a type, and are represented by
    cp_parser_trait as a special BASES tree instead of a TRAIT_TYPE tree.  */
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 87c2e8a7111..3527f596983 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12273,6 +12273,10 @@ finish_trait_type (cp_trait_kind kind, tree
type1, tree type2)
       if (TYPE_REF_P (type1))
  type1 = TREE_TYPE (type1);
       return cv_unqualified (type1);
+    case CPTK_ADD_POINTER:
+      if (TYPE_REF_P (type1))
+    type1 = TREE_TYPE (type1);
+      return build_pointer_type (type1);

 #define DEFTRAIT_EXPR(CODE, NAME, ARITY) \
     case CPTK_##CODE:
diff --git a/gcc/testsuite/g++.dg/ext/add_pointer.C
b/gcc/testsuite/g++.dg/ext/add_pointer.C
new file mode 100644
index 00000000000..e35873553c8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/add_pointer.C
@@ -0,0 +1,46 @@
+// { dg-do compile { target c++11 } }
+
+#define SA(X) static_assert((X),#X)
+
+SA(__is_same(__add_pointer(int), int*));
+SA(__is_same(__add_pointer(const int), const int*));
+SA(__is_same(__add_pointer(volatile int), volatile int*));
+SA(__is_same(__add_pointer(const volatile int), const volatile int*));
+
+SA(__is_same(__add_pointer(int*), int**));
+SA(__is_same(__add_pointer(const int*), const int**));
+SA(__is_same(__add_pointer(volatile int*), volatile int**));
+SA(__is_same(__add_pointer(const volatile int*), const volatile int**));
+
+SA(__is_same(__add_pointer(int* const), int* const*));
+SA(__is_same(__add_pointer(int* volatile), int* volatile*));
+SA(__is_same(__add_pointer(int* const volatile), int* const volatile*));
+
+SA(__is_same(__add_pointer(int&), int*));
+SA(__is_same(__add_pointer(const int&), const int*));
+SA(__is_same(__add_pointer(volatile int&), volatile int*));
+SA(__is_same(__add_pointer(const volatile int&), const volatile int*));
+
+SA(__is_same(__add_pointer(int&&), int*));
+SA(__is_same(__add_pointer(const int&&), const int*));
+SA(__is_same(__add_pointer(volatile int&&), volatile int*));
+SA(__is_same(__add_pointer(const volatile int&&), const volatile int*));
+
+SA(__is_same(__add_pointer(int[3]), int(*)[3]));
+SA(__is_same(__add_pointer(const int[3]), const int(*)[3]));
+SA(__is_same(__add_pointer(volatile int[3]), volatile int(*)[3]));
+SA(__is_same(__add_pointer(const volatile int[3]), const volatile int(*)[3]));
+
+SA(__is_same(__add_pointer(int(*)[3]), int(**)[3]));
+SA(__is_same(__add_pointer(const int(*)[3]), const int(**)[3]));
+SA(__is_same(__add_pointer(volatile int(*)[3]), volatile int(**)[3]));
+SA(__is_same(__add_pointer(const volatile int(*)[3]), const volatile
int(**)[3]));
+
+SA(__is_same(__add_pointer(int(* const)[3]), int(* const*)[3]));
+SA(__is_same(__add_pointer(int(* volatile)[3]), int(* volatile*)[3]));
+SA(__is_same(__add_pointer(int(* const volatile)[3]), int(* const
volatile*)[3]));
+
+SA(__is_same(__add_pointer(int(int)), int(*)(int)));
+SA(__is_same(__add_pointer(int(* const)(int)), int(* const*)(int)));
+SA(__is_same(__add_pointer(int(* volatile)(int)), int(* volatile*)(int)));
+SA(__is_same(__add_pointer(int(* const volatile)(int)), int(* const
volatile*)(int)));
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index f343e153e56..bed4f932bfa 100644
--- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
+++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
@@ -146,3 +146,6 @@
 #if !__has_builtin (__remove_cvref)
 # error "__has_builtin (__remove_cvref) failed"
 #endif
+#if !__has_builtin (__add_pointer)
+# error "__has_builtin (__add_pointer) failed"
+#endif