Re: Full disable of C++20 time zone support

[Alexey Lapshin <alexey.lapshin@espressif.com>]

> Which target are you building for?

riscv32-esp-elf

build with gcc v4.9.2

> I think this should fix it:

This brings next errors:


gcc/libstdc++-v3/src/c++20/tzdb.cc:157:27: error: 'list_mutex' was not declared in this scope
gcc/libstdc++-v3/src/c++20/tzdb.cc:158:28: error: 'using std::chrono::tzdb_list::_Node::head_ptr = class std::atomic<std::shared_ptr<std::chrono::tzdb_list::_Node> >' {aka 'class std::atomic<std::shared_ptr<std::chrono::tzdb_list::_Node> >'} has no member named 'get'



Why it could not be disabled at all? like this:


--- a/libstdc++-v3/src/c++20/tzdb.cc
+++ b/libstdc++-v3/src/c++20/tzdb.cc
@@ -22,6 +22,8 @@
 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 // <http://www.gnu.org/licenses/>.
 
+#ifndef TZDB_DISABLED
+
 // The -Wabi warnings in this file are all for non-exported symbols.
 #pragma GCC diagnostic ignored "-Wabi"
 
@@ -2037,3 +2039,5 @@ namespace std::chrono
   } // namespace
 #endif // TZDB_DISABLED
 } // namespace std::chrono
+
+#endif



On Wed, 2023-06-28 at 20:40 +0100, Jonathan Wakely wrote:
> [External: This email originated outside Espressif]
> 
> 
> On Wed, 28 Jun 2023 at 20:33, Jonathan Wakely <jwakely@redhat.com> wrote:
> > On Wed, 28 Jun 2023 at 19:42, Alexey Lapshin wrote:
> > > Hi!
> > > 
> > > I faced an issue with compiling libstdc++-v3/src/c++20/tzdb.cc:
> > > 
> > > 
> > > [ERROR]    gcc/libstdc++-v3/src/c++20/tzdb.cc:110:21: error: 'constinit' variable 'std::chrono::{anonymous}::list_mutex' does not have a constant initializer
> > > [ERROR]    gcc/libstdc++-v3/src/c++20/tzdb.cc:110:21: error: call to non-'constexpr' function 'std::mutex::mutex()'
> > > 
> > > 
> > 
> > 
> > Which target are you building for?
> > 
> >  
> > > 
> > > Any plans to create a configure option to disable tzdb from build? Or at least make it compilable?
> > > 
> > > Tried --with-libstdcxx-zoneinfo=no but it does not take effect, because it does not cover line with the bug.
> > > 
> > 
> > 
> > Well then we should fix that. We don't want *another* configure option when we already have two for tzdb.
> > 
> 
> 
> I think this should fix it:
> 
> --- a/libstdc++-v3/src/c++20/tzdb.cc
> +++ b/libstdc++-v3/src/c++20/tzdb.cc
> @@ -43,8 +43,8 @@
>  
>  #ifndef __GTHREADS
>  # define USE_ATOMIC_SHARED_PTR 0
> -#elif _WIN32
> -// std::mutex cannot be constinit, so Windows must use atomic<shared_ptr<>>.
> +#elif ! defined __GTHREAD_MUTEX_INIT
> +// std::mutex cannot be constinit, so must use atomic<shared_ptr<>>.
>  # define USE_ATOMIC_SHARED_PTR 1
>  #elif ATOMIC_POINTER_LOCK_FREE < 2
>  # define USE_ATOMIC_SHARED_PTR 0
> 
>