Request to update libc++ related packages for current Clang/LLVM toolchain

Takashi Yano takashi.yano@nifty.ne.jp
Sun Jan 18 08:43:36 GMT 2026


On Sun, 18 Jan 2026 01:22:32 -0700
Brian Inglis wrote:
> On 2026-01-18 00:45, Takashi Yano via Cygwin wrote:
> > On Sun, 18 Jan 2026 00:35:37 +0000, kikairoya via Cygwin wrote:
> >> 2026年1月15日 21:53:21 (+09:00) で、Takashi Yano via Cygwin さんが書きました:
> >>> The resulted a.exe will be free from libgcc_s. Please try.
> 
> >> Using compiler-rt instead of libgcc_s requires extra attention in Cygwin,
> >> because the emulated TLS functionality implemented in compiler-rt can't
> >> share the storage across DLL boundaries.
> 
> > Thanks for pointing this out.
> > The comment in the emutls.c explains that.
> > https://github.com/llvm/llvm-project/blob/main/compiler-rt/lib/builtins/emutls.c#L378-L389
> > Do you think this is a defect we should accept?
> 
> Is there a reason why llvm/clang/compiler-rt can not use Cygwin TLS and must use 
> Emulated TLS?

I think so. gcc also uses its own emutls.

> Should this discussion be moved to -developers as that level of knowledge seems 
> to be required?

Maybe.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>


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