On 14/06/20 22:40 +0000, Paul Keir wrote:
Hi,
Upon constexpr evaluation, char_traits move uses copy_backward, but its last
argument should be to the range end rather than its beginning. I include the
fix and a test.
This is my first patch, so if it looks OK, perhaps someone could commit for me.
The patch is fine, and small enough to not need a copyright
assignment, so I've tested it and committed it. Thanks very much!
I've also committed the attached patch, which bumps the feature test
macro to indicate support for this feature. That macro is not defined
by the C++ committee, but I'm treating that as a defect and will get
it added.
Tested powerpc64le-linux, committed to master.
commit b6ab9ecd550227684643b41e9e33a4d3466724d8
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Mon Jun 15 14:31:26 2020 +0100
libstdc++: Update value of __cpp_lib_constexpr_char_traits for C++20
Although not required by SD-6 or the C++20 draft, we define the macro
__cpp_lib_constexpr_char_traits to indicate support for P0432R1. This
updates the value in C++20 mode for the P1032R1 changes to char_traits.
* include/bits/char_traits.h (__cpp_lib_constexpr_char_traits):
Update value for C++20.
* include/std/version (__cpp_lib_constexpr_char_traits): Likewise.
* testsuite/21_strings/char_traits/requirements/constexpr_functions_c++17.cc:
Update expected value.
* testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc:
Likewise.
diff --git a/libstdc++-v3/include/bits/char_traits.h b/libstdc++-v3/include/bits/char_traits.h
index c623a6713f6..84c2d1b7ff2 100644
--- a/libstdc++-v3/include/bits/char_traits.h
+++ b/libstdc++-v3/include/bits/char_traits.h
@@ -236,7 +236,14 @@ namespace std _GLIBCXX_VISIBILITY(default)
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#if __cplusplus >= 201703L
-#define __cpp_lib_constexpr_char_traits 201611
+
+#if __cplusplus == 201703L
+// Unofficial macro indicating P0426R1 support
+# define __cpp_lib_constexpr_char_traits 201611L
+#else
+// Also support P1032R1 in C++20
+# define __cpp_lib_constexpr_char_traits 201811L
+#endif
/**
* @brief Determine whether the characters of a NULL-terminated
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index c6bde2cfbda..f64aff4f520 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -127,7 +127,7 @@
#define __cpp_lib_boyer_moore_searcher 201603
#define __cpp_lib_chrono 201611
#define __cpp_lib_clamp 201603
-#define __cpp_lib_constexpr_char_traits 201611
+#define __cpp_lib_constexpr_char_traits 201611L
#define __cpp_lib_enable_shared_from_this 201603
#define __cpp_lib_execution 201902L // FIXME: should be 201603L
#define __cpp_lib_filesystem 201703
@@ -192,16 +192,18 @@
#if _GLIBCXX_HOSTED
#undef __cpp_lib_array_constexpr
+#undef __cpp_lib_constexpr_char_traits
#define __cpp_lib_array_constexpr 201811L
#define __cpp_lib_assume_aligned 201811L
#define __cpp_lib_bind_front 201907L
// FIXME: #define __cpp_lib_execution 201902L
#define __cpp_lib_integer_comparison_functions 202002L
#define __cpp_lib_constexpr_algorithms 201806L
+#define __cpp_lib_constexpr_char_traits 201811L
#define __cpp_lib_constexpr_complex 201711L
#define __cpp_lib_constexpr_dynamic_alloc 201907L
#define __cpp_lib_constexpr_functional 201907L
-# define __cpp_lib_constexpr_iterator 201811L
+#define __cpp_lib_constexpr_iterator 201811L
#define __cpp_lib_constexpr_memory 201811L
#define __cpp_lib_constexpr_numeric 201911L
#define __cpp_lib_constexpr_string_view 201811L
diff --git a/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++17.cc b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++17.cc
index 7cb950b89f5..55dcba48db6 100644
--- a/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++17.cc
+++ b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++17.cc
@@ -75,8 +75,10 @@ template<typename CT>
#ifndef __cpp_lib_constexpr_char_traits
# error Feature-test macro for constexpr char_traits is missing
-#elif __cpp_lib_constexpr_char_traits != 201611
+#elif __cpp_lib_constexpr_char_traits < 201611
# error Feature-test macro for constexpr char_traits has the wrong value
+#elif __cpp_lib_constexpr_char_traits > 201611 && __cplusplus == 201703
+# error Feature-test macro for constexpr char_traits has wrong value for C++17
#endif
static_assert( test_assign<std::char_traits<char>>() );
diff --git a/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc
index 6358640c1cb..63c7c9cbb57 100644
--- a/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc
+++ b/libstdc++-v3/testsuite/21_strings/char_traits/requirements/constexpr_functions_c++20.cc
@@ -32,7 +32,7 @@ template<typename CT>
#ifndef __cpp_lib_constexpr_char_traits
# error Feature-test macro for constexpr char_traits is missing
-#elif __cpp_lib_constexpr_char_traits != 201611
+#elif __cpp_lib_constexpr_char_traits != 201811
# error Feature-test macro for constexpr char_traits has the wrong value
#endif
