The P3379R0 bump to __cpp_lib_constrained_equality relates to changes
that only affect std::expected, so there's no reason to define the
updated value in C++20.
This change restores the previous value (202403) for C++20, and only
uses the new value (202411) for C++23 and later.
Also remove the TODO comments, because I correctly predicted that the
final value would be 202411.
libstdc++-v3/ChangeLog:
* include/bits/version.def (constrained_equality): Only define
as 202411 for C++23 and later, use 202403 for C++20.
* include/bits/version.h: Regenerate.
* testsuite/20_util/expected/equality_constrained.cc: Remove
TODO comment.
---
Tested x86_64-linux. Pushed to trunk.
N.B. strictly speaking neither of the papers that modified the
__cpp_lib_constrained_equality macro (P2944R3 and P3379R0) were approved
as a DR, so it's a C++26 feature. But we support the constraints back to
C++20 (or back to C++23 for std::expected). Defaulted comparisons work
better if these comparisons are properly constrained.
libstdc++-v3/include/bits/version.def | 7 ++++++-
libstdc++-v3/include/bits/version.h | 7 ++++++-
.../testsuite/20_util/expected/equality_constrained.cc | 2 +-
3 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/libstdc++-v3/include/bits/version.def
b/libstdc++-v3/include/bits/version.def
index 8f609b469cc..2ec1b40bd38 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -1273,7 +1273,12 @@ ftms = {
ftms = {
name = constrained_equality;
values = {
- v = 202411; // FIXME: 202403 for P2944R3, ??? for P3379R0
+ v = 202411;
+ cxxmin = 23;
+ extra_cond = "__glibcxx_three_way_comparison";
+ };
+ values = {
+ v = 202403;
cxxmin = 20;
extra_cond = "__glibcxx_three_way_comparison";
};
diff --git a/libstdc++-v3/include/bits/version.h
b/libstdc++-v3/include/bits/version.h
index f05c3fd13c0..04c1349c84b 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -1406,11 +1406,16 @@
#undef __glibcxx_want_constexpr_vector
#if !defined(__cpp_lib_constrained_equality)
-# if (__cplusplus >= 202002L) && (__glibcxx_three_way_comparison)
+# if (__cplusplus >= 202100L) && (__glibcxx_three_way_comparison)
# define __glibcxx_constrained_equality 202411L
# if defined(__glibcxx_want_all) ||
defined(__glibcxx_want_constrained_equality)
# define __cpp_lib_constrained_equality 202411L
# endif
+# elif (__cplusplus >= 202002L) && (__glibcxx_three_way_comparison)
+# define __glibcxx_constrained_equality 202403L
+# if defined(__glibcxx_want_all) ||
defined(__glibcxx_want_constrained_equality)
+# define __cpp_lib_constrained_equality 202403L
+# endif
# endif
#endif /* !defined(__cpp_lib_constrained_equality) &&
defined(__glibcxx_want_constrained_equality) */
#undef __glibcxx_want_constrained_equality
diff --git a/libstdc++-v3/testsuite/20_util/expected/equality_constrained.cc
b/libstdc++-v3/testsuite/20_util/expected/equality_constrained.cc
index 7f6cefae748..a079d98129f 100644
--- a/libstdc++-v3/testsuite/20_util/expected/equality_constrained.cc
+++ b/libstdc++-v3/testsuite/20_util/expected/equality_constrained.cc
@@ -4,7 +4,7 @@
#ifndef __cpp_lib_constrained_equality
# error "Feature-test macro for constrained_equality missing in <expected>"
-#elif __cpp_lib_constrained_equality < 202411L // TODO: use final value
+#elif __cpp_lib_constrained_equality < 202411L
# error "Feature-test macro for constrained_equality has wrong value"
#endif
--
2.49.0
