[PATCH] libstdc++: Improve ostream output for std::stacktrace

[Jonathan Wakely]

On Thu, 16 Oct 2025, 07:00 Nathan Myers, <ncm@cantrip.org> wrote:

> On 10/15/25 9:54 PM, Nathan Myers wrote:
> > On 10/15/25 5:02 PM, Jonathan Wakely wrote:
> ...
> >> --- a/libstdc++-v3/include/std/stacktrace
> >> +++ b/libstdc++-v3/include/std/stacktrace
> >> @@ -134,6 +134,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> >>       friend ostream&
> >>       operator<<(ostream&, const stacktrace_entry&);
> >> +    struct _Print_pc
> >> +    {
> >> +      native_handle_type _M_pc;
> >> +
> >> +      friend ostream&
> >> +      operator<<(ostream& __os, _Print_pc __pc)
> >> +      {
> >> +    if (__pc._M_pc != (native_handle_type)-1) [[likely]]
> >> +      __os << "[0x" << std::hex << __pc._M_pc << std::dec << ']';
> >
> > Maybe save the output radix, and restore it.
>
> Like
>
>    auto __flags = __os.setf(__os.hex, __os.basefield);
>    __os << "[0x" << __pc._M_pc << ']';
>    __os.flags(__flags);
>

Ah yes, we don't know that it's initially 'dec' so should not set it to
that unconditionally.



>
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