Re: [PATCH] Cygwin: fix build with GCC 7

[Corinna Vinschen]

On Apr 17 10:54, Yaakov Selkowitz wrote:
> GCC 7 is able to see straight through this trick, so use a more formal
> method to avoid the warning.
> 
> Signed-off-by: Yaakov Selkowitz 
> ---
>  winsup/cygwin/random.cc | 14 +-
>  1 file changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/winsup/cygwin/random.cc b/winsup/cygwin/random.cc
> index 802c33b8a..163fc040c 100644
> --- a/winsup/cygwin/random.cc
> +++ b/winsup/cygwin/random.cc
> @@ -279,14 +279,6 @@ srandom(unsigned x)
>   (void)random();
>  }
>  
> -/* Avoid a compiler warning when we really want to get at the junk in
> -   an uninitialized variable. */
> -static unsigned long
> -dummy (unsigned volatile long *x)
> -{
> -  return *x;
> -}
> -
>  /*
>   * srandomdev:
>   *
> @@ -313,7 +305,11 @@ srandomdev()
>   unsigned long junk;
>  
>   gettimeofday(, NULL);
> - srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ 
> dummy());
> + /* Avoid a compiler warning when we really want to get at the
> +junk in an uninitialized variable. */
> +#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
> + srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk);
> +#pragma GCC diagnostic pop
>   return;
>   }
>  
> -- 
> 2.17.0

Yes, please push.


Thanks,
Corinna

-- 
Corinna Vinschen  Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat


signature.asc
Description: PGP signature

[PATCH] Cygwin: fix build with GCC 7

[Yaakov Selkowitz]

GCC 7 is able to see straight through this trick, so use a more formal
method to avoid the warning.

Signed-off-by: Yaakov Selkowitz 
---
 winsup/cygwin/random.cc | 14 +-
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/winsup/cygwin/random.cc b/winsup/cygwin/random.cc
index 802c33b8a..163fc040c 100644
--- a/winsup/cygwin/random.cc
+++ b/winsup/cygwin/random.cc
@@ -279,14 +279,6 @@ srandom(unsigned x)
(void)random();
 }
 
-/* Avoid a compiler warning when we really want to get at the junk in
-   an uninitialized variable. */
-static unsigned long
-dummy (unsigned volatile long *x)
-{
-  return *x;
-}
-
 /*
  * srandomdev:
  *
@@ -313,7 +305,11 @@ srandomdev()
unsigned long junk;
 
gettimeofday(, NULL);
-   srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ 
dummy());
+   /* Avoid a compiler warning when we really want to get at the
+  junk in an uninitialized variable. */
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+   srandom((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk);
+#pragma GCC diagnostic pop
return;
}
 
-- 
2.17.0