https://gcc.gnu.org/g:6c272ca18b5226fe850049409ae5e36b80cf879b
commit r16-4450-g6c272ca18b5226fe850049409ae5e36b80cf879b Author: Jonathan Wakely <[email protected]> Date: Wed Oct 15 14:59:20 2025 +0100 libstdc++: Remove invalid entry from the end of std::stacktrace The backtrace_simple function seems to consistently invoke the callback with an invalid -1UL value as the last entry, which seems to come from _Unwind_Backtrace. The glibc backtrace(3) function has a special case to not include that final invalid address, but libbacktrace doesn't seem to handle it. Do so in std::stacktrace::current() instead. libstdc++-v3/ChangeLog: * include/std/stacktrace (basic_stacktrace::current): Call _M_trim before returning. (basic_stacktrace::_M_trim): New member function. Diff: --- libstdc++-v3/include/std/stacktrace | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/libstdc++-v3/include/std/stacktrace b/libstdc++-v3/include/std/stacktrace index 01e18ba171c0..b9e260e19f89 100644 --- a/libstdc++-v3/include/std/stacktrace +++ b/libstdc++-v3/include/std/stacktrace @@ -208,6 +208,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { if (_S_current(__cb, std::__addressof(__ret))) __ret._M_clear(); + else + __ret._M_trim(); } return __ret; } @@ -224,6 +226,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { if (_S_current(__cb, std::__addressof(__ret), __skip)) __ret._M_clear(); + else + __ret._M_trim(); } return __ret; @@ -260,6 +264,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } } } + else + __ret._M_trim(); } return __ret; } @@ -651,6 +657,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } }; + void + _M_trim() noexcept + { + // libbacktrace adds an invalid -1UL entry at the end, remove it. + if (!empty() && !end()[-1]) + _M_impl._M_resize(size() - 1, _M_alloc); + } + [[no_unique_address]] allocator_type _M_alloc{}; _Impl _M_impl{};
