https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96345
Derek Huang <djh458 at stern dot nyu.edu> changed:
What |Removed |Added
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CC| |djh458 at stern dot nyu.edu
--- Comment #7 from Derek Huang <djh458 at stern dot nyu.edu> ---
I'm using GCC 11.3 and see the same issue with __cxa_demangle.
In my case, I have a C++ template specialization where the mangled type name
exceeds 1k characters. I guess c++filt and nm (using nm -C) are both using
__cxa_demangle, as both were unable to demangle that very long type name as
well as a couple others created from related specializations of the template.
Originally (several months ago), I worked around this issue with
abi::__cxa_demangle by using llvm::itaniumDemangle. However, I recently spent
some time using compile-time parsing of __PRETTY_FUNCTION__ to get a demangled
type name, and I see that __PRETTY_FUNCTION__ *does* demangle properly.
So if you need a workaround, there are a couple options:
1. Use llvm::itaniumDemangle by static linking against LLVMDemangle
2. Parse __PRETTY_FUNCTION__ with something like the following:
// requires C++17 for std::string_view and constexpr std::begin
template <typename T>
constexpr std::string_view type_name() noexcept
{
auto begin = std::begin(__PRETTY_FUNCTION__);
/* advance begin to where the T type begins */
auto end = begin;
/* advance end to where the T type ends */
return {begin, static_cast<std::size_t>(end - begin)};
}
It would be nice to have __cxa_demangle working, however, as it is the official
way to demangle a string mangled following the Itanium ABI.
