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Re: Clang-built Gawk 5.2.1 regex oddity

From: Sam James
Subject: Re: Clang-built Gawk 5.2.1 regex oddity
Date: Tue, 3 Jan 2023 02:14:38 +0000

> On 2 Jan 2023, at 06:10, Paul Eggert <eggert@cs.ucla.edu> wrote:
> This is a serious bug in Clang: it generates incorrect machine code.
> [snip]
> My guess is that Clang got confused because dfaerror is declared _Noreturn, 
> so Clang mistakenly assumed that dfawarn is also _Noreturn, which it is not.
> I worked around the Clang bug by installed the attached patch into Gnulib. 
> Please give it a try with Gawk.

Confirmed this mitigates the problem. I had to apply it manually to support/ as 
I couldn't immediately see how to sync gnulib myself, but that's no big deal.

> Incorrect code generation is a serious bug in Clang; can you please report it 
> to the Clang folks? I am considering using a bigger hammer, and doing this:

Kenton's done this at https://github.com/llvm/llvm-project/issues/59792 now.

>   #define _Noreturn /*empty*/
> whenever Clang is used, until the bug is fixed.

maskray's analysis so far at 
agrees with yours, which would mean
this is likely a good idea.

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