[PATCH v2 1/2] c++: implement __is_array built-in trait

[Ken Matsui <kmatsui@cs.washington.edu>]

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

gcc/cp/ChangeLog:

	* cp-trait.def: Define __is_array.
	* constraint.cc (diagnose_trait_expr): Handle CPTK_IS_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_array.
	* g++.dg/ext/is_array.C: New test.

Signed-off-by: Ken Matsui <kmatsui@cs.washington.edu>
---
 gcc/cp/constraint.cc                     |  3 +++
 gcc/cp/cp-trait.def                      |  1 +
 gcc/cp/semantics.cc                      |  4 ++++
 gcc/testsuite/g++.dg/ext/has-builtin-1.C |  3 +++
 gcc/testsuite/g++.dg/ext/is_array.C      | 28 ++++++++++++++++++++++++
 5 files changed, 39 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_array.C

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 8cf0f2d0974..7cec7eba591 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3751,6 +3751,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_IS_UNION:
       inform (loc, "  %qT is not a union", t1);
       break;
+    case CPTK_IS_ARRAY:
+      inform (loc, "  %qT is not an array", t1);
+      break;
     case CPTK_IS_AGGREGATE:
       inform (loc, "  %qT is not an aggregate", t1);
       break;
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index 8b7fece0cc8..f68c7f2e8ec 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -82,6 +82,7 @@ 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_UNION, "__is_union", 1)
+DEFTRAIT_EXPR (IS_ARRAY, "__is_array", 1)
 DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)
 DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY, "__reference_converts_from_temporary", 2)
 /* FIXME Added space to avoid direct usage in GCC 13.  */
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8fb47fd179e..22f2700ec0b 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12118,6 +12118,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_UNION:
       return type_code1 == UNION_TYPE;
 
+    case CPTK_IS_ARRAY:
+      return type_code1 == ARRAY_TYPE;
+
     case CPTK_IS_ASSIGNABLE:
       return is_xible (MODIFY_EXPR, type1, type2);
 
@@ -12296,6 +12299,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_ENUM:
     case CPTK_IS_UNION:
     case CPTK_IS_SAME:
+    case CPTK_IS_ARRAY:
       break;
 
     case CPTK_IS_LAYOUT_COMPATIBLE:
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index f343e153e56..56485ae62be 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 (__is_array)
+# error "__has_builtin (__is_array) failed"
+#endif
diff --git a/gcc/testsuite/g++.dg/ext/is_array.C b/gcc/testsuite/g++.dg/ext/is_array.C
new file mode 100644
index 00000000000..facfed5c7cb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_array.C
@@ -0,0 +1,28 @@
+// { 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, X, expect) \
+  SA(TRAIT(X) == expect);                  \
+  SA(TRAIT(const X) == expect);            \
+  SA(TRAIT(volatile X) == expect);         \
+  SA(TRAIT(const volatile X) == expect)
+
+SA_TEST_CATEGORY(__is_array, int[2], true);
+SA_TEST_CATEGORY(__is_array, int[], true);
+SA_TEST_CATEGORY(__is_array, int[2][3], true);
+SA_TEST_CATEGORY(__is_array, int[][3], true);
+SA_TEST_CATEGORY(__is_array, float*[2], true);
+SA_TEST_CATEGORY(__is_array, float*[], true);
+SA_TEST_CATEGORY(__is_array, float*[2][3], true);
+SA_TEST_CATEGORY(__is_array, float*[][3], true);
+SA_TEST_CATEGORY(__is_array, ClassType[2], true);
+SA_TEST_CATEGORY(__is_array, ClassType[], true);
+SA_TEST_CATEGORY(__is_array, ClassType[2][3], true);
+SA_TEST_CATEGORY(__is_array, ClassType[][3], true);
+
+// Sanity check.
+SA_TEST_CATEGORY(__is_array, ClassType, false);
-- 
2.41.0