[PATCH 11/14] c++: Implement __is_signed built-in trait

[Ken Matsui <kmatsui@gcc.gnu.org>]

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

gcc/cp/ChangeLog:

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

gcc/testsuite/ChangeLog:

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

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 gcc/cp/constraint.cc                     |  3 ++
 gcc/cp/cp-trait.def                      |  1 +
 gcc/cp/semantics.cc                      |  6 ++++
 gcc/testsuite/g++.dg/ext/has-builtin-1.C |  3 ++
 gcc/testsuite/g++.dg/ext/is_signed.C     | 45 ++++++++++++++++++++++++
 5 files changed, 58 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/is_signed.C

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 7e4b3cd38c4..d2e41aa053d 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3813,6 +3813,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_IS_SCOPED_ENUM:
       inform (loc, "  %qT is not a scoped enum", t1);
       break;
+    case CPTK_IS_SIGNED:
+      inform (loc, "  %qT is not a signed type", t1);
+      break;
     case CPTK_IS_STD_LAYOUT:
       inform (loc, "  %qT is not an standard layout type", t1);
       break;
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index 734522eb5ba..6dac7622a7c 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -88,6 +88,7 @@ DEFTRAIT_EXPR (IS_POLYMORPHIC, "__is_polymorphic", 1)
 DEFTRAIT_EXPR (IS_REFERENCE, "__is_reference", 1)
 DEFTRAIT_EXPR (IS_SAME, "__is_same", 2)
 DEFTRAIT_EXPR (IS_SCOPED_ENUM, "__is_scoped_enum", 1)
+DEFTRAIT_EXPR (IS_SIGNED, "__is_signed", 1)
 DEFTRAIT_EXPR (IS_STD_LAYOUT, "__is_standard_layout", 1)
 DEFTRAIT_EXPR (IS_TRIVIAL, "__is_trivial", 1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 522db3f57e4..c3d6fc2d10f 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12548,6 +12548,11 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_SCOPED_ENUM:
       return SCOPED_ENUM_P (type1);
 
+    case CPTK_IS_SIGNED:
+      return (integral_type_p (type1)
+	|| floating_point_type_p (type1))
+	&& TYPE_SIGN (type1) == SIGNED;
+
     case CPTK_IS_STD_LAYOUT:
       return std_layout_type_p (type1);
 
@@ -12740,6 +12745,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_REFERENCE:
     case CPTK_IS_SAME:
     case CPTK_IS_SCOPED_ENUM:
+    case CPTK_IS_SIGNED:
     case CPTK_IS_UNION:
     case CPTK_IS_UNSIGNED:
       break;
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index 062b06234e6..e3d16add403 100644
--- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
+++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
@@ -146,6 +146,9 @@
 #if !__has_builtin (__is_scoped_enum)
 # error "__has_builtin (__is_scoped_enum) failed"
 #endif
+#if !__has_builtin (__is_signed)
+# error "__has_builtin (__is_signed) failed"
+#endif
 #if !__has_builtin (__is_standard_layout)
 # error "__has_builtin (__is_standard_layout) failed"
 #endif
diff --git a/gcc/testsuite/g++.dg/ext/is_signed.C b/gcc/testsuite/g++.dg/ext/is_signed.C
new file mode 100644
index 00000000000..a46ba54ac14
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_signed.C
@@ -0,0 +1,45 @@
+// { dg-do compile { target c++11 } }
+
+#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_signed, void, false);
+
+SA_TEST_CATEGORY(__is_signed, bool, bool(-1) < bool(0));
+SA_TEST_CATEGORY(__is_signed, char, char(-1) < char(0));
+SA_TEST_CATEGORY(__is_signed, signed char, true);
+SA_TEST_CATEGORY(__is_signed, unsigned char, false);
+SA_TEST_CATEGORY(__is_signed, wchar_t, wchar_t(-1) < wchar_t(0));
+SA_TEST_CATEGORY(__is_signed, short, true);
+SA_TEST_CATEGORY(__is_signed, unsigned short, false);
+SA_TEST_CATEGORY(__is_signed, int, true);
+SA_TEST_CATEGORY(__is_signed, unsigned int, false);
+SA_TEST_CATEGORY(__is_signed, long, true);
+SA_TEST_CATEGORY(__is_signed, unsigned long, false);
+SA_TEST_CATEGORY(__is_signed, long long, true);
+SA_TEST_CATEGORY(__is_signed, unsigned long long, false);
+
+SA_TEST_CATEGORY(__is_signed, float, true);
+SA_TEST_CATEGORY(__is_signed, double, true);
+SA_TEST_CATEGORY(__is_signed, long double, true);
+
+#ifndef __STRICT_ANSI__
+// GNU Extensions.
+#ifdef __SIZEOF_INT128__
+SA_TEST_CATEGORY(__is_signed, __int128, true);
+SA_TEST_CATEGORY(__is_signed, unsigned __int128, false);
+#endif
+
+#ifdef _GLIBCXX_USE_FLOAT128
+SA_TEST_CATEGORY(__is_signed, __float128, true);
+#endif
+#endif
+
+// Sanity check.
+class ClassType { };
+SA_TEST_CATEGORY(__is_signed, ClassType, false);
-- 
2.43.0