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Re: [Qemu-devel] [5466] Only use __builtin_* with GCC >= 3.4
From: |
M. Warner Losh |
Subject: |
Re: [Qemu-devel] [5466] Only use __builtin_* with GCC >= 3.4 |
Date: |
Sun, 12 Oct 2008 13:10:51 -0600 (MDT) |
In message: <address@hidden>
Avi Kivity <address@hidden> writes:
: Jamie Lokier wrote:
: > Glibc uses "#if __GNUC_PREREQ (3,4)" which is quite neat.
: > Do "grep -R GNUC_PREREQ /usr/include".
: >
: > I use (and define if not already defined) the same macro in my
: > programs, on the assumption that the macro's meaning is unlikely to
: > ever change or be different elsewhere.
: >
:
: It's illegal to define or use an identifier beginning with two
: underscores, unless it's documented by the implementation. What if
: glibc adds a third argument? All your apps wil break.
Lots of things would break :-(
: You should define your own macros for this, with a non-__ name.
Identifiers starting with __ are reserved for the implementation.
They aren't illegal, per se, just reserved.
Warner