Re: [PATCH] gdb/python/python-internal.h: avoid uninitialized constexpr

[Lancelot SIX <Lancelot.Six@amd.com>]

On 18/06/2024 20:48, Tom Tromey wrote:
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> 
> Lancelot> Just gave a try to this approach, I end up linker errors regarding
> Lancelot> duplicated symbols:
> 
> Lancelot> I have not really looked if there is a way to work-around that.
> 
> I think s/constexpr/extern probably works.
> Would you mind trying that?
> 
> Tom

G++ complains that "explicit template specialization cannot have a 
storage class":

In file included from ../../gdb/python/py-arch.c:23:
../../gdb/python/python-internal.h:154:13: error: ‘gdbpy_method_format’ 
initialized and declared ‘extern’ [-Werror]
   154 | extern char gdbpy_method_format<gdb_py_longest> = GDB_PY_LL_ARG[0];
       |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../gdb/python/python-internal.h:154:1: error: explicit template 
specialization cannot have a storage class
   154 | extern char gdbpy_method_format<gdb_py_longest> = GDB_PY_LL_ARG[0];
       | ^~~~~~

Clang++ complains because "'extern' variable has an initializer".  I 
know the empty struct as a base template, and add static constexpr 
members for template specializations is a bit verbose, but to the best 
of my knowledge it is the "c++ way".

Lancelot.