Re: [PATCH] libstdc++: Deliver names of C functions in <stacktrace>

[Jonathan Wakely <jwakely@redhat.com>]

On Tue, 13 Dec 2022 at 21:03, Björn Schäpers <gcc@hazardy.de> wrote:
>
> From: Björn Schäpers <bjoern@hazardy.de>
>
> One could add (), these are not part of __name. One could also try to
> check upfront if __cxa_demangle should be called at all.


Thanks for the patch, I'll push this.

I think we do want to check whether to call __cxa_demangle, because
otherwise an extern "C" function called simply "g" will get demangled
to "__float128" and that's not right!

So I think we should check whether the function name starts with "_Z"
which indicates a C++ function name. That can be improved later
though.



>
> -- >8 --
>
> Tested on i686-w64-mingw32.
>
> __cxa_demangle is only to demangle C++ names, for all C functions,
> extern "C" functions, and including main it returns -2, in that case
> just adapt the given name. Otherwise it's kept empty, which doesn't look
> nice in the stacktrace.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/stacktrace (stacktrace_entry::_S_demangle): Use
>         raw __name if __cxa_demangle could not demangle it.
>
> Signed-off-by: Björn Schäpers <bjoern@hazardy.de>
> ---
>  libstdc++-v3/include/std/stacktrace | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/stacktrace b/libstdc++-v3/include/std/stacktrace
> index 83c6463b0d8..5baf2dcdaca 100644
> --- a/libstdc++-v3/include/std/stacktrace
> +++ b/libstdc++-v3/include/std/stacktrace
> @@ -219,6 +219,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>                                                &__status);
>        if (__status == 0)
>         __s = __str;
> +      else
> +       __s = __name;
>        __builtin_free(__str);
>        return __s;
>      }
> --
> 2.38.1
>