[committed] libstdc++: Correct value of __cpp_lib_constexpr_exceptions [PR117785]

[Jonathan Wakely]

Only P3068R6 (Allowing exception throwing in constant-evaluation) is
implemented in the library so far, so the value of the
constexpr_exceptions feature test macro should be 202411L. Once we
support the library changes in P3378R2 (constexpr exception types) then
we can set the value to 202502L again.

libstdc++-v3/ChangeLog:

        PR libstdc++/117785
        * include/bits/version.def (constexpr_exceptions): Define
        correct value.
        * include/bits/version.h: Regenerate.
        * libsupc++/exception: Check correct value.
        * testsuite/18_support/exception/version.cc: New test.
---

Tested x86_64-linux. Pushed to trunk.

 libstdc++-v3/include/bits/version.def                  |  2 +-
 libstdc++-v3/include/bits/version.h                    |  4 ++--
 libstdc++-v3/libsupc++/exception                       |  1 +
 libstdc++-v3/testsuite/18_support/exception/version.cc | 10 ++++++++++
 4 files changed, 14 insertions(+), 3 deletions(-)
 create mode 100644 libstdc++-v3/testsuite/18_support/exception/version.cc

diff --git a/libstdc++-v3/include/bits/version.def 
b/libstdc++-v3/include/bits/version.def
index df58e7018d81..cf0672b48224 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -2053,7 +2053,7 @@ ftms = {
 ftms = {
   name = constexpr_exceptions;
   values = {
-    v = 202502;
+    v = 202411;
     cxxmin = 26;
     extra_cond = "__cpp_constexpr_exceptions >= 202411L";
   };
diff --git a/libstdc++-v3/include/bits/version.h 
b/libstdc++-v3/include/bits/version.h
index 1414dd78ddab..c01ddf14dd57 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -2301,9 +2301,9 @@
 
 #if !defined(__cpp_lib_constexpr_exceptions)
 # if (__cplusplus >  202302L) && (__cpp_constexpr_exceptions >= 202411L)
-#  define __glibcxx_constexpr_exceptions 202502L
+#  define __glibcxx_constexpr_exceptions 202411L
 #  if defined(__glibcxx_want_all) || 
defined(__glibcxx_want_constexpr_exceptions)
-#   define __cpp_lib_constexpr_exceptions 202502L
+#   define __cpp_lib_constexpr_exceptions 202411L
 #  endif
 # endif
 #endif /* !defined(__cpp_lib_constexpr_exceptions) && 
defined(__glibcxx_want_constexpr_exceptions) */
diff --git a/libstdc++-v3/libsupc++/exception b/libstdc++-v3/libsupc++/exception
index 25ce8d97e315..fc6f8d927711 100644
--- a/libstdc++-v3/libsupc++/exception
+++ b/libstdc++-v3/libsupc++/exception
@@ -38,6 +38,7 @@
 #include <bits/exception.h>
 
 #define __glibcxx_want_uncaught_exceptions
+#define __glibcxx_want_constexpr_exceptions
 #define __glibcxx_want_exception_ptr_cast
 #include <bits/version.h>
 
diff --git a/libstdc++-v3/testsuite/18_support/exception/version.cc 
b/libstdc++-v3/testsuite/18_support/exception/version.cc
new file mode 100644
index 000000000000..09a2d102b720
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/exception/version.cc
@@ -0,0 +1,10 @@
+// { dg-do preprocess { target c++26 } }
+// { dg-add-options no_pch }
+
+#include <exception>
+
+#ifndef __cpp_lib_constexpr_exceptions
+# error "Feature test macro for constexpr_exceptions is missing in <exception>"
+#elif __cpp_lib_constexpr_exceptions < 202411L
+# error "Feature test macro for constexpr_exceptions has wrong value in 
<exception>"
+#endif
-- 
2.50.1