[gcc r15-1534] libstdc++: Fix __cpp_lib_chrono for old std::string ABI

[Jonathan Wakely via Libstdc++-cvs]

https://gcc.gnu.org/g:f906b107634bfac29676e7fcf364d0ca7ceed666

commit r15-1534-gf906b107634bfac29676e7fcf364d0ca7ceed666
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Thu Jun 20 13:28:08 2024 +0100

    libstdc++: Fix __cpp_lib_chrono for old std::string ABI
    
    The <chrono> header is incomplete for the old std::string ABI, because
    std::chrono::tzdb is only defined for the new ABI. The feature test
    macro advertising full C++20 support should not be defined for the old
    ABI.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/version.def (chrono): Add cxx11abi = yes.
            * include/bits/version.h: Regenerate.
            * testsuite/std/time/syn_c++20.cc: Adjust expected value for
            the feature test macro.

Diff:
---
 libstdc++-v3/include/bits/version.def        |  1 +
 libstdc++-v3/include/bits/version.h          |  2 +-
 libstdc++-v3/testsuite/std/time/syn_c++20.cc | 11 +++++++++--
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/include/bits/version.def 
b/libstdc++-v3/include/bits/version.def
index 683b967d54b..42cdef2f526 100644
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -574,6 +574,7 @@ ftms = {
     v = 201907;
     cxxmin = 20;
     hosted = yes;
+    cxx11abi = yes; // std::chrono::tzdb requires cxx11 std::string
   };
   values = {
     v = 201611;
diff --git a/libstdc++-v3/include/bits/version.h 
b/libstdc++-v3/include/bits/version.h
index 4850041c0a3..1eaf3733bc2 100644
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -639,7 +639,7 @@
 #undef __glibcxx_want_boyer_moore_searcher
 
 #if !defined(__cpp_lib_chrono)
-# if (__cplusplus >= 202002L) && _GLIBCXX_HOSTED
+# if (__cplusplus >= 202002L) && _GLIBCXX_USE_CXX11_ABI && _GLIBCXX_HOSTED
 #  define __glibcxx_chrono 201907L
 #  if defined(__glibcxx_want_all) || defined(__glibcxx_want_chrono)
 #   define __cpp_lib_chrono 201907L
diff --git a/libstdc++-v3/testsuite/std/time/syn_c++20.cc 
b/libstdc++-v3/testsuite/std/time/syn_c++20.cc
index f0b86199e9d..4a527262e9d 100644
--- a/libstdc++-v3/testsuite/std/time/syn_c++20.cc
+++ b/libstdc++-v3/testsuite/std/time/syn_c++20.cc
@@ -20,9 +20,16 @@
 
 #include <chrono>
 
+// std::chrono::tzdb is not defined for the old std::string ABI.
+#if _GLIBCXX_USE_CXX_ABI
+# define EXPECTED_VALUE 201907L
+#else
+# define EXPECTED_VALUE 201611L
+#endif
+
 #ifndef __cpp_lib_chrono
 # error "Feature test macro for chrono is missing in <chrono>"
-#elif __cpp_lib_chrono < 201907L
+#elif __cpp_lib_chrono < EXPECTED_VALUE
 # error "Feature test macro for chrono has wrong value in <chrono>"
 #endif
 
@@ -94,7 +101,7 @@ namespace __gnu_test
   using std::chrono::make12;
   using std::chrono::make24;
 
-#if _GLIBCXX_USE_CXX11_ABI
+#if __cpp_lib_chrono >= 201803L
   using std::chrono::tzdb;
   using std::chrono::tzdb_list;
   using std::chrono::get_tzdb;