From: Erik Faye-Lund <kusmabite@googlemail.com>
Date: Fri, 16 Apr 2010 06:58:00 GMT
Subject: Re: [PATCH] Building Git on Tru64
Message-ID: <h2y40aa078e1004152358s66299ef9p55d454902113c7d4@mail.gmail.com>
In-Reply-To: <m34ojcfly1.fsf@localhost.localdomain>

On Thu, Apr 15, 2010 at 11:24 PM, Jakub Narebski <jnareb@gmail.com> wrote:
> "Daniel Richard G." <skunk@iSKUNK.ORG> writes:
>
>> On Thu, 2010 Apr 15 21:29+0200, Alex Riesen wrote:
>> >
>> > That one may be better handled at one place (git-compat-util.h?) with
>> > something like:
>> >
>> >   #ifdef Tru64
>> >   #define MAP_FAILED ((void *)MAP_FAILED)
>> >   #endif
>>
>> I agree with the sentiment, but you can't have a macro refer to itself
>
> It can.  From (cpp.info)
>
>  3.10.5 Self-Referential Macros
>  ------------------------------
>
>  <snip>  It is passed into the
>  preprocessor output unchanged.
>

Not very useful in this case, no?

$ echo "#define MAP_FAILED (-1L)
#define MAP_FAILED ((void *)MAP_FAILED)
void *v = MAP_FAILED" | gcc -x c -
<stdin>:2:1: warning: "MAP_FAILED" redefined
<stdin>:1:1: warning: this is the location of the previous definition
<stdin>:3: error: 'MAP_FAILED' undeclared here (not in a function)
<stdin>:3: error: expected ',' or ';' at end of input
$ echo "#define MAP_FAILED (-1L)
#define MAP_FAILED ((void *)MAP_FAILED)
void *v = MAP_FAILED" | cpp
# 1 "<stdin>"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "<stdin>"
<stdin>:2:1: warning: "MAP_FAILED" redefined
<stdin>:1:1: warning: this is the location of the previous definition


void *v = ((void *)MAP_FAILED)
$

-- 
Erik "kusma" Faye-Lund