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Date:   Tue, 15 Oct 2019 16:28:48 +0200
From:   Christian Brauner <christian.brauner@ubuntu.com>
To:     Christian Kellner <ckellner@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Christian Kellner <christian@kellner.me>,
        Shuah Khan <shuah@kernel.org>, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH] pidfd: fix selftest compilation by removing linux/wait.h
Message-ID: <20191015142847.fa5ypv2qrocbuifd@wittgenstein>
References: <20191011163811.8607-1-ckellner@redhat.com>
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On Fri, Oct 11, 2019 at 06:38:11PM +0200, Christian Kellner wrote:
> From: Christian Kellner <christian@kellner.me>
> 
> The pidfd_{open,poll}_test.c files both include `linux/wait.h` and
> later `sys/wait.h`. The former has `#define P_ALL 0`, but in the
> latter P_ALL is part of idtype_t enum, where it gets substituted
> due to the aforementioned define to be `0`, which then results in
> `typedef enum {0, ...`, which then results into a compiler error:
> "error: expected identifier before numeric constant".
> Since we need `sys/wait.h` for waitpid, drop `linux/wait.h`.
> 
> Signed-off-by: Christian Kellner <christian@kellner.me>

Sorry, I missed this patch.
This is problematic and your patch would only temporarily fix it.
If glibc adds a P_PIDFD to the enum we'll run into the same issue.
So please:
- remove the linux/wait.h header (as you've already done here)
- add a custom define for P_PIDFD under a different name, e.g.:
  #ifndef __P_PIDFD
  #define __P_PIDFD 3
  #endif
  and add a comment above it explaining the reason for this mess.


Thanks and (_ugh_)
Christian