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Re: [patch] Error on setenv(..., NULL, ...)

From: Paul Eggert <eggert at cs dot ucla dot edu>
To: Paul Pluzhnikov <ppluzhnikov at google dot com>
Cc: Roland McGrath <roland at hack dot frob dot com>, Szabolcs Nagy <szabolcs dot nagy at arm dot com>, Joseph Myers <joseph at codesourcery dot com>, GLIBC Devel <libc-alpha at sourceware dot org>, "mtk at man7 dot org" <mtk at man7 dot org>
Date: Sun, 15 Mar 2015 21:11:48 -0700
Subject: Re: [patch] Error on setenv(..., NULL, ...)
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Paul Pluzhnikov wrote:

I assume you also know about DIAG_PUSH_NEEDS_COMMENT /
DIAG_POP_NEEDS_COMMENT, which then makes me not understand your
comment about selective pacification.

When I tried to use those macros, I still got the warning and the build stillfailed. Part of the problem is that 'vallen' gets used as part of an argumentto the __mempcpy/memcpy macros, and GCC decides that since 'vallen' is used inthe macro body, it'll issue a warning since the macro body is outside the"scope" of the DIAG_PUSH* and DIAG_POP* brackets. It's the classic problem ofmacro capture.

I couldn't even use plain DIAG_IGNORE_NEEDS_COMMENT (i.e., withoutDIAG_PUSH_NEEDS_COMMENT), because I needed to put the #pragma before including<errno.h> (the first standard include) -- otherwise I got the warning -- andDIAG_IGNORE_NEEDS_COMMENT isn't defined until after <errno.h> is included.


I was using GCC 4.9.2 20150212 (Red Hat 4.9.2-6), for what that's worth.

Follow-Ups:
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Joseph Myers

References:
- [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Joseph Myers
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Szabolcs Nagy
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Eggert
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Roland McGrath
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Eggert
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Roland McGrath
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Eggert
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Eggert
- Re: [patch] Error on setenv(..., NULL, ...)
  - From: Paul Pluzhnikov

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