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Re: Fwd: sed porting trouble

From: Bruno Haible
Subject: Re: Fwd: sed porting trouble
Date: Tue, 5 Oct 2010 22:15:55 +0200
User-agent: KMail/1.9.9

Hi Paul,

> Wouldn't it be simpler just to have
> in the .in.h file, and then have that expand into
> all the relevant pragmas, including #pragma COLUMNS?

This would imply either removing the #if __GNUC__ >= 3 guard,
or using a multi-line expansion of @address@hidden

1) Why removing #if __GNUC__ >= 3 guard does not work:
Recall that this #if exists so that the headers are as standalone as
possible, with the goal that
  - Packages can install these headers in public locations.
    libunistring does this, I think some of Simon's packages as well.
  - Large packages can have parts compiled by GCC and other parts by a non-GCC

In the second use-case, when the library gets built and installed with cc,
and then gets used with gcc. @PRAGMA_SYSTEM_HEADER@ would expand to empty in
the file, and then gcc would produce warnings (in -pedantic mode, IIRC)
because the #pragma is absent.

In the first use-case there is actually no problem (see the generation of
unistring/stdint.h in libunistring/lib/Makefile.am for the reason), but
we would be on very thin ice here.

2) Why a multi-line expansion of @PRAGMA_SYSTEM_HEADER@ does not work:
I explained this in

In summary, it's more robust to use a 4-line idiom here than a one-liner.


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