Build error with GCC4.8 on Fedora19

[Omair Majid]

On 07/24/2013 02:33 PM, Alan Bateman wrote:
> On 10/07/2013 12:01, Omair Majid wrote:
>> On 07/09/2013 03:40 AM, Erik Joelsson wrote:
>>> I would like to see a comment explaining why the option was needed. Is
>>> this a bug in gcc or has the checking just become better?
>> -Werror is not a great default. It means "all warnings are errors". The
>> set of warnings that a compiler emits changes all the time. Users and
>> distributions can enable additional warnings by default. Newer compiler
>> versions may omit additional warnings. So on any compiler other than the
>> typical compiler used, extra warnings are possible. With -Werror, this
>> will probably fail. Lots of people discourage it [1].
>>
>> We have been setting SCTP_WERROR="" to disable this -Werror on Fedora
>> builds [2].
>>
> I'm curious if there was a conclusion on this one. I assume SCTP_WERROR
> was originally intended for building libsctp (not libnio) so it would be
> strange to add to SCTP_WERROR to disable -Werror for issues coming from
> the file system code. One other thing that isn't clear is why there
> aren't other warnings as there are many other JNI functions in this
> source file that don't use the "jclass this" parameter.

I believe the original reporter made a mistake here. Only libsctp is
being built with -Werror. My build logs shows messages like:

/home/omajid/devel/jdk8-build-sctp-clean/jdk/src/solaris/native/sun/nio/fs/UnixNativeDispatcher.c:
In function ‘Java_sun_nio_fs_UnixNativeDispatcher_init’:
/home/omajid/devel/jdk8-build-sctp-clean/jdk/src/solaris/native/sun/nio/fs/UnixNativeDispatcher.c:176:63:
warning: unused parameter ‘this’ [-Wunused-parameter]
 Java_sun_nio_fs_UnixNativeDispatcher_init(JNIEnv* env, jclass this)

This is just a warning. This part of the build is not using -Werror, so
things continue on just fine.

But when building libsctp, the message is different:

/home/omajid/devel/jdk8-build-sctp-clean/jdk/src/solaris/native/sun/nio/ch/sctp/SctpNet.c:
In function ‘JNI_OnLoad’:
/home/omajid/devel/jdk8-build-sctp-clean/jdk/src/solaris/native/sun/nio/ch/sctp/SctpNet.c:47:12:
error: unused parameter ‘vm’ [-Werror=unused-parameter]
   (JavaVM *vm, void *reserved) {
            ^
This is an error and causes the build to fail.

Hope that clarifies things. I would still like to see this SCTP_WERROR
be removed (or at least filtered with explicit -Werror=<list of known
warnings to fail on>).

Thanks,
Omair

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