[libcxx-dev] Option to disable inline namespacing completely?

Eric Fiselier via libcxx-dev libcxx-dev at lists.llvm.org
Wed Nov 14 09:04:27 PST 2018

The itanium specification provides special compressed mangled names for
std::string when it's not in an inline namespace [1]

Specifically, `Ss` vs `St3__112basic_string`

[1] https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling-compression

On Wed, Nov 14, 2018 at 10:03 AM Marshall Clow via libcxx-dev <
libcxx-dev at lists.llvm.org> wrote:

> On Sun, Nov 11, 2018 at 9:49 PM Kristina Brooks via libcxx-dev <
> libcxx-dev at lists.llvm.org> wrote:
>> Hi,
>> I was wondering, would it be possible to add an option to disable inline
>> namespacing completely (as a CMake
>> configuration flag) in libc++ for the sake of being able to use shorthand
>> mangling and without having to resort to
>> handling it on IA64 mangler level. This has many use cases for example
>> distributions of anything that includes libc++ as
>> one and only libc++ and does not allow non-vendor software to be
>> installed. On an embedded system, assuming debug info
>> is generated, and given how common some of the debug data takes a very
>> significant amount of space given the complex
>> definition of something like `std::__2::basic_string<...>` versus the
>> short form (`std::string` having a shorthand
>> mangling is a godsend since it's 95% shorter, not an accurate figure but
>> basically definitely above 90%).
> I'm confused here.
> Why are you comparing `std::string` to `std::__2::basic_string<......" ?
> `std::__2::string` is quite short.
> <http://lists.llvm.org/cgi-bin/mailman/listinfo/libcxx-dev>
> -- Marshall
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