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From: Fangrui Song <>
Subject: Re: [musl] [PATCH] Use __builtin_FILE/__builtin_LINE if available
Date: Tue, 21 Feb 2023 11:09:14 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sat, Feb 18, 2023 at 4:17 AM Jon Chesterfield
<> wrote:
> On Sat, 18 Feb 2023, 02:54 Fangrui Song, <> wrote:
> On Fri, Feb 17, 2023 at 6:03 PM Rich Felker <> wrote:
> >
> > On Fri, Feb 17, 2023 at 05:33:33PM -0800, Fangrui Song wrote:
> > > C++ inline functions are requred to have exact same sequence of tokens
> > > in every translation unit, but __FILE__ and __LINE__ may expand to
> > > different tokens. The ODR violatioin is usually benign, but it can lead
> > > to errors when C++20 modules are used.
> It is sad that C++ modules broke 'assert' but not surprising. Modules were largely created out of aversion to macros. This isn't something libc can fix though, I suggest a defect report against C++ instead.
> Changing the semantics of assert in C seems like a bad thing to do.
> Thanks

I disagree. This is a footgun where the right fix (or workaround, if
you prefer) is on the libc side. It is fairly reasonable for a header
to use assert and not expect two includes using different paths to not
cause C++ module problems.

The current module behavior regarding macros is a reasonable
compromise. It can be evolved (e.g.

  reply	other threads:[~2023-02-21 19:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-18  1:33 Fangrui Song
2023-02-18  2:03 ` Rich Felker
2023-02-18  2:53   ` Fangrui Song
2023-02-18 12:17     ` Jon Chesterfield
2023-02-21 19:09       ` Fangrui Song [this message]
2023-02-27 22:26         ` Szabolcs Nagy
2023-03-02  8:19           ` Fangrui Song
     [not found]           ` <>
2023-03-05  3:23             ` Zhihao Yuan
2023-02-21 19:45       ` Jeffrey Walton

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