c++: Implement __is_unbounded_array built-in trait

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

gcc/cp/ChangeLog:

	* cp-trait.def: Define __is_unbounded_array.
	* constraint.cc (diagnose_trait_expr): Handle
	CPTK_IS_UNBOUNDED_ARRAY.
	* semantics.cc (trait_expr_value): Likewise.
	(finish_trait_expr): Likewise.

gcc/testsuite/ChangeLog:

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

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>

gcc/cp/constraint.cc

@@ -3809,6 +3809,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_IS_TRIVIALLY_COPYABLE:
       inform (loc, "  %qT is not trivially copyable", t1);
       break;
+    case CPTK_IS_UNBOUNDED_ARRAY:
+      inform (loc, "  %qT is not an unbounded array", t1);
+      break;
     case CPTK_IS_UNION:
       inform (loc, "  %qT is not a union", t1);
       break;

gcc/cp/cp-trait.def

@@ -83,6 +83,7 @@ DEFTRAIT_EXPR (IS_TRIVIAL, "__is_trivial", 1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
 DEFTRAIT_EXPR (IS_TRIVIALLY_CONSTRUCTIBLE, "__is_trivially_constructible", -1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
+DEFTRAIT_EXPR (IS_UNBOUNDED_ARRAY, "__is_unbounded_array", 1)
 DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
 DEFTRAIT_EXPR (IS_VOLATILE, "__is_volatile", 1)
 DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)

gcc/cp/semantics.cc

@@ -12082,6 +12082,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_TRIVIALLY_COPYABLE:
       return trivially_copyable_p (type1);
 
+    case CPTK_IS_UNBOUNDED_ARRAY:
+      return array_of_unknown_bound_p (type1);
+
     case CPTK_IS_UNION:
       return type_code1 == UNION_TYPE;
 
@@ -12249,6 +12252,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_CONST:
     case CPTK_IS_ENUM:
     case CPTK_IS_SAME:
+    case CPTK_IS_UNBOUNDED_ARRAY:
     case CPTK_IS_UNION:
     case CPTK_IS_VOLATILE:
       break;

gcc/testsuite/g++.dg/ext/has-builtin-1.C

@@ -131,6 +131,9 @@
 #if !__has_builtin (__is_trivially_copyable)
 # error "__has_builtin (__is_trivially_copyable) failed"
 #endif
+#if !__has_builtin (__is_unbounded_array)
+# error "__has_builtin (__is_unbounded_array) failed"
+#endif
 #if !__has_builtin (__is_union)
 # error "__has_builtin (__is_union) failed"
 #endif

gcc/testsuite/g++.dg/ext/is_unbounded_array.C

@@ -0,0 +1,37 @@
+// { dg-do compile { target c++11 } }
+
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+#define SA(X) static_assert((X),#X)
+
+#define SA_TEST_CATEGORY(TRAIT, TYPE, EXPECT)	\
+  SA(TRAIT(TYPE) == EXPECT);					\
+  SA(TRAIT(const TYPE) == EXPECT);				\
+  SA(TRAIT(volatile TYPE) == EXPECT);			\
+  SA(TRAIT(const volatile TYPE) == EXPECT)
+
+SA_TEST_CATEGORY(__is_unbounded_array, int[2], false);
+SA_TEST_CATEGORY(__is_unbounded_array, int[], true);
+SA_TEST_CATEGORY(__is_unbounded_array, int[2][3], false);
+SA_TEST_CATEGORY(__is_unbounded_array, int[][3], true);
+SA_TEST_CATEGORY(__is_unbounded_array, float*[2], false);
+SA_TEST_CATEGORY(__is_unbounded_array, float*[], true);
+SA_TEST_CATEGORY(__is_unbounded_array, float*[2][3], false);
+SA_TEST_CATEGORY(__is_unbounded_array, float*[][3], true);
+SA_TEST_CATEGORY(__is_unbounded_array, ClassType[2], false);
+SA_TEST_CATEGORY(__is_unbounded_array, ClassType[], true);
+SA_TEST_CATEGORY(__is_unbounded_array, ClassType[2][3], false);
+SA_TEST_CATEGORY(__is_unbounded_array, ClassType[][3], true);
+SA_TEST_CATEGORY(__is_unbounded_array, IncompleteClass[2][3], false);
+SA_TEST_CATEGORY(__is_unbounded_array, IncompleteClass[][3], true);
+SA_TEST_CATEGORY(__is_unbounded_array, int(*)[2], false);
+SA_TEST_CATEGORY(__is_unbounded_array, int(*)[], false);
+SA_TEST_CATEGORY(__is_unbounded_array, int(&)[2], false);
+SA_TEST_CATEGORY(__is_unbounded_array, int(&)[], false);
+
+// Sanity check.
+SA_TEST_CATEGORY(__is_unbounded_array, ClassType, false);
+SA_TEST_CATEGORY(__is_unbounded_array, IncompleteClass, false);
+SA_TEST_CATEGORY(__is_unbounded_array, IncompleteUnion, false);