RFR [XXS] : JDK-8081616: build fixes for --disable-warnings-as-errors

[David Holmes]

On 2/06/2015 7:57 PM, David Holmes wrote:
> On 2/06/2015 6:58 PM, Magnus Ihse Bursie wrote:
>> On 2015-06-01 19:23, Bertrand Delsart wrote:
>>> Hi all,
>>>
>>> A small open webrev to fix some issues around
>>> --disable-warnings-as-errors (this is not a full cleanup):
>>>
>>> http://cr.openjdk.java.net/~bdelsart/8081616/webrev.00/webrev/
>>>
>>> Without the fix, -Werror is used to compiled native JDK libraries even
>>> when the --disable-warnings-as-errors is used.
>>>
>>> A lot of these libs are addressed by clearing
>>> CFLAGS_WARNINGS_ARE_ERRORS in flags.m4
>>>
>>> Lib-jdk.sctp.gmk is a special case because it uses directly -Werror.
>>> Instead of modifying SCTP to use CFLAGS_WARNINGS_ARE_ERRORS, I use the
>>> mechanism put in place in that file to disable -Werror and control it
>>> through the WARNINGS_AS_ERRORS configured value.
>> I think this patch will require some work to be OK.
>>
>> First of all, I'm not quite sure I understand what problem you are
>> trying to solve. What libraries are compiled with -Werror when
>> --disable-warnings-as-errors is used? This should not be the case, and I
>> cannot reproduce it on my system.
>>
>> CFLAGS_WARNINGS_ARE_ERRORS should never be cleared, since that is only
>> exported as the mechanism to use for enabling warnings as errors. If no
>> compilation includes it (which it should not if warnings-as-errors are
>> disabled), it won't affect the build. If CFLAGS_WARNINGS_ARE_ERRORS are
>> used even though warnings-as-errors are disabled, then it is this usage
>> that should be fixed.
>
> AFAICS most uses of CFLAGS_WARNINGS_ARE_ERRORS are unconditional eg:
>
> $(eval $(call SetupNativeCompilation,BUILD_LIBINSTRUMENT, \
>      LIBRARY := instrument, \
>      OUTPUT_DIR := $(INSTALL_LIBRARIES_HERE), \
>      SRC := $(LIBINSTRUMENT_SRC), \
>      OPTIMIZATION := LOW, \
>      CFLAGS := $(LIBINSTRUMENT_CFLAGS) $(CFLAGS_WARNINGS_ARE_ERRORS), \
>
> So clearing it is the simplest way to avoid it being applied.

Aside: this looks like a bug:

./lib/Lib-jdk.jdwp.agent.gmk

$(eval $(call SetupNativeCompilation,BUILD_LIBDT_SOCKET, \
     LIBRARY := dt_socket, \
     OUTPUT_DIR := $(INSTALL_LIBRARIES_HERE), \
     SRC := $(LIBDT_SOCKET_SRC), \
     OPTIMIZATION := LOW, \
     CFLAGS := $(CFLAGS_JDKLIB) $(CFLAGS_CFLAGS_WARNINGS_ARE_ERRORS) 
-DUSE_MMAP \

CFLAGS_CFLAGS ?

David

> David
> -----
>
>
>
>> I can see that libsctp is a special case that hard-codes -Werror. But in
>> this case we should remove the hard-coding and relying on the system
>> setting. This is probably a remnant from before the overall -Werror
>> usage, where the authors of a specific lib wanted to enforce a higher
>> standard. Also, it might be worth revisiting if
>> -Wno-error=unused-parameter is really needed. These things tend to
>> bit-rot.
>>
>> /Magnus
>>
>>>
>>> Best regards,
>>>
>>> Bertrand.
>>>
>>