Fix 'libstdc++-v3/src/c++20/tzdb.cc' build for '__GTHREADS && !__GTHREADS_CXX0X' configurations (was: libstdc++: '_GLIBCXX_HAS_GTHREADS' -- '__GTHREADS' vs. '__GTHREADS_CXX0X')

[Thomas Schwinge]

Hi!

On 2025-02-20T16:36:56+0000, Jonathan Wakely <jwakely@redhat.com> wrote:
> On 20/02/25 15:50 +0100, Thomas Schwinge wrote:
>>From 820e015494e25187c9a5ffbd69911ec6ce612789 Mon Sep 17 00:00:00 2001
>>From: Jonathan Wakely <jwakely@redhat.com>
>>Date: Thu, 20 Feb 2025 14:08:11 +0000
>>Subject: [PATCH] Fix 'libstdc++-v3/src/c++20/tzdb.cc' build for '__GTHREADS &&
>> !__GTHREADS_CXX0X' configurations
>>
>>	libstdc++-v3/
>>	* src/c++20/tzdb.cc [__GTHREADS && !__GTHREADS_CXX0X]: Use
>>	'__gnu_cxx::__mutex'.
>>
>>Co-authored-by: Thomas Schwinge <tschwinge@baylibre.com>
>>---
>> libstdc++-v3/src/c++20/tzdb.cc | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>>diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
>>index 7e8cce7ce8c..70ba7b0ef53 100644
>>--- a/libstdc++-v3/src/c++20/tzdb.cc
>>+++ b/libstdc++-v3/src/c++20/tzdb.cc
>>@@ -35,6 +35,9 @@
>> #include <atomic>     // atomic<T*>, atomic<int>
>> #include <memory>     // atomic<shared_ptr<T>>
>> #include <mutex>      // mutex
>>+#if defined __GTHREADS && ! defined _GLIBCXX_HAS_GHTREADS
>>+# include <ext/concurrence.h> // __gnu_cxx::__mutex
>>+#endif
>> #include <filesystem> // filesystem::read_symlink
>> 
>> #ifndef _AIX
>>@@ -97,11 +100,14 @@ namespace std::chrono
>> {
>>   namespace
>>   {
>>-#if ! USE_ATOMIC_SHARED_PTR
>> #ifndef __GTHREADS
>>     // Dummy no-op mutex type for single-threaded targets.
>>     struct mutex { void lock() { } void unlock() { } };
>>+#elif ! defined _GLIBCXX_HAS_GHTREADS
>
> This still has my GHTREADS typo.

Eh.  I had fixed that, but apparently lost it.  Re-fixed.

> A comment here would be good too:
>
>      // Use __gnu_cxx::__mutex is std::mutex isn't available.

Added.

>>+    using mutex = __gnu_cxx::__mutex;
>> #endif
>>+
>>+#if ! USE_ATOMIC_SHARED_PTR
>>     inline mutex& list_mutex()
>>     {
>> #ifdef __GTHREAD_MUTEX_INIT
>
> Strictly speaking, we also need a change here, because unlike
> std::mutex, __gnu_cxx::__mutex can't be initialized with `constinit`.
> But that can wait, because it's not needed for your configuration.

I've added an '#error' for such a configuration.  (But happy to drop, if
you think that's overkill.)

Please see v2 of
"Fix 'libstdc++-v3/src/c++20/tzdb.cc' build for '__GTHREADS && !__GTHREADS_CXX0X' configurations"
attached.  Still only GCN, nvptx build-tested.


Grüße
 Thomas


-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Fix-libstdc-v3-src-c-20-tzdb.cc-build-for-__GTHREADS.patch
Type: text/x-diff
Size: 1687 bytes
Desc: not available
URL: <https://gcc.gnu.org/pipermail/libstdc++/attachments/20250220/c6211b02/attachment.bin>