[PATCH] Fix warning caused by unused-result in bug-atexit3-lib.cc

[PATCH] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Gabriel F. T. Gomes]

The test case dlfcn/bug-atexit3-lib.cc calls write and doesn't check the
result.  When building with GCC 6.2 from IBM's branch, this generates a
warning in 'make check', which is treated as an error.  This patch adds a
return variable to get rid of the warning and of the error.

Tested for powerpc64le.

2016-10-28  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>

	* dlfcn/bug-atexit3-lib.cc (statclass): Assign return of call to
	write (defined with __wur) to unused variable.
---
 dlfcn/bug-atexit3-lib.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/dlfcn/bug-atexit3-lib.cc b/dlfcn/bug-atexit3-lib.cc
index 3d01ea8..5a7c454 100644
--- a/dlfcn/bug-atexit3-lib.cc
+++ b/dlfcn/bug-atexit3-lib.cc
@@ -4,11 +4,15 @@ struct statclass
 {
   statclass()
   {
-    write (1, "statclass\n", 10);
+    size_t unused_ret;
+    (void) unused_ret;
+    unused_ret = write (1, "statclass\n", 10);
   }
   ~statclass()
   {
-    write (1, "~statclass\n", 11);
+    size_t unused_ret;
+    (void) unused_ret;
+    unused_ret = write (1, "~statclass\n", 11);
   }
 };
 
-- 
2.4.11

Re: [PATCH] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Florian Weimer]

On 10/28/2016 03:00 PM, Gabriel F. T. Gomes wrote:
> The test case dlfcn/bug-atexit3-lib.cc calls write and doesn't check the
> result.  When building with GCC 6.2 from IBM's branch, this generates a
> warning in 'make check', which is treated as an error.  This patch adds a
> return variable to get rid of the warning and of the error.

You could use write_message from test-skeleton.c instead.  it has a 
proper unused variable guard.

Thanks,
Florian

Re: [PATCH] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Gabriel F. T. Gomes]

On Fri, 28 Oct 2016 15:04:13 +0200
Florian Weimer <fweimer@redhat.com> wrote:

> On 10/28/2016 03:00 PM, Gabriel F. T. Gomes wrote:
> > The test case dlfcn/bug-atexit3-lib.cc calls write and doesn't check the
> > result.  When building with GCC 6.2 from IBM's branch, this generates a
> > warning in 'make check', which is treated as an error.  This patch adds a
> > return variable to get rid of the warning and of the error.  
> 
> You could use write_message from test-skeleton.c instead.  it has a 
> proper unused variable guard.

Is it ok to use write_message in c++ code being built as object?

Thanks,
Gabriel

Re: [PATCH] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Florian Weimer]

On 10/28/2016 03:32 PM, Gabriel F. T. Gomes wrote:
> On Fri, 28 Oct 2016 15:04:13 +0200
> Florian Weimer <fweimer@redhat.com> wrote:
>
>> On 10/28/2016 03:00 PM, Gabriel F. T. Gomes wrote:
>>> The test case dlfcn/bug-atexit3-lib.cc calls write and doesn't check the
>>> result.  When building with GCC 6.2 from IBM's branch, this generates a
>>> warning in 'make check', which is treated as an error.  This patch adds a
>>> return variable to get rid of the warning and of the error.
>>
>> You could use write_message from test-skeleton.c instead.  it has a
>> proper unused variable guard.
>
> Is it ok to use write_message in c++ code being built as object?

Oh, right, this probably will not work.  Bummer.

You could copy the function into the .cc file, though.  The unused 
attribute may be needed in the long term.

Florian

[PATCH v2] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Gabriel F. T. Gomes]

Changes since v1:
  - Copy write_message from test-skeleton.c to dlfcn/bug-atexit3-lib.cc.
  - Replace calls to write with calls to write_message.

---8<---
The test case dlfcn/bug-atexit3-lib.cc calls write and doesn't check the
result.  When building with GCC 6.2, this generates a warning in 'make
check', which is treated as an error.  This patch replaces the call to
write with a call to write_message.

Tested for powerpc64le.

2016-10-28  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>

	* dlfcn/bug-atexit3-lib.cc (write_message): New function, copied
	from test-skeleton.c.
	(statclass): Replace calls to write with calls to write_message.
---
 dlfcn/bug-atexit3-lib.cc | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/dlfcn/bug-atexit3-lib.cc b/dlfcn/bug-atexit3-lib.cc
index 3d01ea8..aba7720 100644
--- a/dlfcn/bug-atexit3-lib.cc
+++ b/dlfcn/bug-atexit3-lib.cc
@@ -1,14 +1,22 @@
 #include <unistd.h>
+#include <string.h>
+
+static void
+write_message (const char *message)
+{
+  ssize_t unused __attribute__ ((unused));
+  unused = write (STDOUT_FILENO, message, strlen (message));
+}
 
 struct statclass
 {
   statclass()
   {
-    write (1, "statclass\n", 10);
+    write_message ("statclass\n");
   }
   ~statclass()
   {
-    write (1, "~statclass\n", 11);
+    write_message ("~statclass\n");
   }
 };
 
-- 
2.4.11

Re: [PATCH v2] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Florian Weimer]

On 10/28/2016 07:57 PM, Gabriel F. T. Gomes wrote:

> 2016-10-28  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>
>
> 	* dlfcn/bug-atexit3-lib.cc (write_message): New function, copied
> 	from test-skeleton.c.
> 	(statclass): Replace calls to write with calls to write_message.

Looks good to me.

Thanks,
Florian

Re: [PATCH v2] Fix warning caused by unused-result in bug-atexit3-lib.cc

[Gabriel F. T. Gomes]

On Fri, 28 Oct 2016 22:38:10 +0200
Florian Weimer <fweimer@redhat.com> wrote:

> On 10/28/2016 07:57 PM, Gabriel F. T. Gomes wrote:
> 
> > 2016-10-28  Gabriel F. T. Gomes  <gftg@linux.vnet.ibm.com>
> >
> > 	* dlfcn/bug-atexit3-lib.cc (write_message): New function, copied
> > 	from test-skeleton.c.
> > 	(statclass): Replace calls to write with calls to write_message.  
> 
> Looks good to me.

Thank you.  Pushed as 1b16ff0b.