Implement P0426: Constexpr for std::char_traits git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291741 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp
index 2c3deae..311064c 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp

@@ -11,14 +11,30 @@
 
 // template<> struct char_traits<char>
 
-// static void assign(char_type& c1, const char_type& c2);
+// static constexpr void assign(char_type& c1, const char_type& c2); // constexpr in C++17
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    char c = '1';
+    std::char_traits<char>::assign(c, 'a');
+    return c == 'a';
+}
+#endif
+
 int main()
 {
     char c = '\0';
     std::char_traits<char>::assign(c, 'a');
     assert(c == 'a');
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
index ba58684..71ab248 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp

@@ -12,10 +12,22 @@
 // template<> struct char_traits<char>
 
 // static int compare(const char_type* s1, const char_type* s2, size_t n);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char>::compare("123", "223", 3) < 0
+        && std::char_traits<char>::compare("223", "123", 3) > 0
+        && std::char_traits<char>::compare("123", "123", 3) == 0;
+}
+#endif
+
 int main()
 {
     assert(std::char_traits<char>::compare("", "", 0) == 0);
@@ -38,4 +50,8 @@
     assert(std::char_traits<char>::compare("223", "123", 3) > 0);
     assert(std::char_traits<char>::compare("133", "123", 3) > 0);
     assert(std::char_traits<char>::compare("124", "123", 3) > 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp
index a640af2..714202e 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp

@@ -12,10 +12,24 @@
 // template<> struct char_traits<char>
 
 // static const char_type* find(const char_type* s, size_t n, const char_type& a);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    constexpr const char *p = "123";
+    return std::char_traits<char>::find(p, 3, '1') == p
+        && std::char_traits<char>::find(p, 3, '2') == p + 1
+        && std::char_traits<char>::find(p, 3, '3') == p + 2
+        && std::char_traits<char>::find(p, 3, '4') == nullptr;
+}
+#endif
+
 int main()
 {
     char s1[] = {1, 2, 3};
@@ -25,4 +39,8 @@
     assert(std::char_traits<char>::find(s1, 3, char(4)) == 0);
     assert(std::char_traits<char>::find(s1, 3, char(0)) == 0);
     assert(std::char_traits<char>::find(NULL, 0, char(0)) == 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
index 56844ef..d93e499 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp

@@ -12,10 +12,22 @@
 // template<> struct char_traits<char>
 
 // static size_t length(const char_type* s);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char>::length("") == 0
+        && std::char_traits<char>::length("abcd") == 4;
+}
+#endif
+
+
 int main()
 {
     assert(std::char_traits<char>::length("") == 0);
@@ -23,4 +35,8 @@
     assert(std::char_traits<char>::length("aa") == 2);
     assert(std::char_traits<char>::length("aaa") == 3);
     assert(std::char_traits<char>::length("aaaa") == 4);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
index 7f223af..e28f906 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp

@@ -12,12 +12,22 @@
 // template<> struct char_traits<char16_t>
 
 // static void assign(char_type& c1, const char_type& c2);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    char16_t c = u'1';
+    std::char_traits<char16_t>::assign(c, u'a');
+    return c == u'a';
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -26,5 +36,9 @@
     std::char_traits<char16_t>::assign(c, u'a');
     assert(c == u'a');
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp
index 7356097..b4be140 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp

@@ -12,12 +12,23 @@
 // template<> struct char_traits<char16_t>
 
 // static int compare(const char_type* s1, const char_type* s2, size_t n);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char16_t>::compare(u"123", u"223", 3) < 0
+        && std::char_traits<char16_t>::compare(u"223", u"123", 3) > 0
+        && std::char_traits<char16_t>::compare(u"123", u"123", 3) == 0;
+}
+#endif
+
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -43,5 +54,9 @@
     assert(std::char_traits<char16_t>::compare(u"133", u"123", 3) > 0);
     assert(std::char_traits<char16_t>::compare(u"124", u"123", 3) > 0);
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp
index 22db05b..852451c 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp

@@ -12,10 +12,24 @@
 // template<> struct char_traits<char16_t>
 
 // static const char_type* find(const char_type* s, size_t n, const char_type& a);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    constexpr const char16_t *p = u"123";
+    return std::char_traits<char16_t>::find(p, 3, u'1') == p
+        && std::char_traits<char16_t>::find(p, 3, u'2') == p + 1
+        && std::char_traits<char16_t>::find(p, 3, u'3') == p + 2
+        && std::char_traits<char16_t>::find(p, 3, u'4') == nullptr;
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -26,5 +40,9 @@
     assert(std::char_traits<char16_t>::find(s1, 3, char16_t(4)) == 0);
     assert(std::char_traits<char16_t>::find(s1, 3, char16_t(0)) == 0);
     assert(std::char_traits<char16_t>::find(NULL, 0, char16_t(0)) == 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp
index ff5a2a9..5d882bd 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp

@@ -12,12 +12,21 @@
 // template<> struct char_traits<char16_t>
 
 // static size_t length(const char_type* s);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char16_t>::length(u"") == 0
+        && std::char_traits<char16_t>::length(u"abcd") == 4;
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -28,5 +37,9 @@
     assert(std::char_traits<char16_t>::length(u"aaa") == 3);
     assert(std::char_traits<char16_t>::length(u"aaaa") == 4);
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp
index 6cd55ea..3739311 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp

@@ -12,12 +12,22 @@
 // template<> struct char_traits<char32_t>
 
 // static void assign(char_type& c1, const char_type& c2);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    char32_t c = U'1';
+    std::char_traits<char32_t>::assign(c, U'a');
+    return c == U'a';
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -26,5 +36,9 @@
     std::char_traits<char32_t>::assign(c, U'a');
     assert(c == U'a');
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp
index 2671b56..1730d06 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp

@@ -12,12 +12,22 @@
 // template<> struct char_traits<char32_t>
 
 // static int compare(const char_type* s1, const char_type* s2, size_t n);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char32_t>::compare(U"123", U"223", 3) < 0
+        && std::char_traits<char32_t>::compare(U"223", U"123", 3) > 0
+        && std::char_traits<char32_t>::compare(U"123", U"123", 3) == 0;
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -43,5 +53,9 @@
     assert(std::char_traits<char32_t>::compare(U"133", U"123", 3) > 0);
     assert(std::char_traits<char32_t>::compare(U"124", U"123", 3) > 0);
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp
index d0b1799..6d201db 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp

@@ -12,10 +12,24 @@
 // template<> struct char_traits<char32_t>
 
 // static const char_type* find(const char_type* s, size_t n, const char_type& a);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    constexpr const char32_t *p = U"123";
+    return std::char_traits<char32_t>::find(p, 3, U'1') == p
+        && std::char_traits<char32_t>::find(p, 3, U'2') == p + 1
+        && std::char_traits<char32_t>::find(p, 3, U'3') == p + 2
+        && std::char_traits<char32_t>::find(p, 3, U'4') == nullptr;
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -26,5 +40,9 @@
     assert(std::char_traits<char32_t>::find(s1, 3, char32_t(4)) == 0);
     assert(std::char_traits<char32_t>::find(s1, 3, char32_t(0)) == 0);
     assert(std::char_traits<char32_t>::find(NULL, 0, char32_t(0)) == 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp
index e0bee5d..9d691ac 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp

@@ -12,12 +12,21 @@
 // template<> struct char_traits<char32_t>
 
 // static size_t length(const char_type* s);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
 #include "test_macros.h"
 
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<char32_t>::length(U"") == 0
+        && std::char_traits<char32_t>::length(U"abcd") == 4;
+}
+#endif
+
 int main()
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
@@ -28,5 +37,9 @@
     assert(std::char_traits<char32_t>::length(U"aaa") == 3);
     assert(std::char_traits<char32_t>::length(U"aaaa") == 4);
 #endif
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp
index 7dcf08c..7a317f0 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp

@@ -12,13 +12,29 @@
 // template<> struct char_traits<wchar_t>
 
 // static void assign(char_type& c1, const char_type& c2);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    wchar_t c = L'1';
+    std::char_traits<wchar_t>::assign(c, L'a');
+    return c == L'a';
+}
+#endif
+
 int main()
 {
     wchar_t c = L'\0';
     std::char_traits<wchar_t>::assign(c, L'a');
     assert(c == L'a');
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp
index 124201b..894560d 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp

@@ -12,10 +12,22 @@
 // template<> struct char_traits<wchar_t>
 
 // static int compare(const char_type* s1, const char_type* s2, size_t n);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<wchar_t>::compare(L"123", L"223", 3) < 0
+        && std::char_traits<wchar_t>::compare(L"223", L"123", 3) > 0
+        && std::char_traits<wchar_t>::compare(L"123", L"123", 3) == 0;
+}
+#endif
+
 int main()
 {
     assert(std::char_traits<wchar_t>::compare(L"", L"", 0) == 0);
@@ -38,4 +50,8 @@
     assert(std::char_traits<wchar_t>::compare(L"223", L"123", 3) > 0);
     assert(std::char_traits<wchar_t>::compare(L"133", L"123", 3) > 0);
     assert(std::char_traits<wchar_t>::compare(L"124", L"123", 3) > 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp
index ead3f32..80aca0e 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp

@@ -12,10 +12,24 @@
 // template<> struct char_traits<wchar_t>
 
 // static const char_type* find(const char_type* s, size_t n, const char_type& a);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    constexpr const wchar_t *p = L"123";
+    return std::char_traits<wchar_t>::find(p, 3, L'1') == p
+        && std::char_traits<wchar_t>::find(p, 3, L'2') == p + 1
+        && std::char_traits<wchar_t>::find(p, 3, L'3') == p + 2
+        && std::char_traits<wchar_t>::find(p, 3, L'4') == nullptr;
+}
+#endif
+
 int main()
 {
     wchar_t s1[] = {1, 2, 3};
@@ -25,4 +39,8 @@
     assert(std::char_traits<wchar_t>::find(s1, 3, wchar_t(4)) == 0);
     assert(std::char_traits<wchar_t>::find(s1, 3, wchar_t(0)) == 0);
     assert(std::char_traits<wchar_t>::find(NULL, 0, wchar_t(0)) == 0);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }

diff --git a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
index 691e968..35cbb2d 100644
--- a/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
+++ b/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp

@@ -12,10 +12,21 @@
 // template<> struct char_traits<wchar_t>
 
 // static size_t length(const char_type* s);
+// constexpr in C++17
 
 #include <string>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER > 14
+constexpr bool test_constexpr()
+{
+    return std::char_traits<wchar_t>::length(L"") == 0
+        && std::char_traits<wchar_t>::length(L"abcd") == 4;
+}
+#endif
+
 int main()
 {
     assert(std::char_traits<wchar_t>::length(L"") == 0);
@@ -23,4 +34,8 @@
     assert(std::char_traits<wchar_t>::length(L"aa") == 2);
     assert(std::char_traits<wchar_t>::length(L"aaa") == 3);
     assert(std::char_traits<wchar_t>::length(L"aaaa") == 4);
+
+#if TEST_STD_VER > 14
+    static_assert(test_constexpr(), "" );
+#endif
 }