[OpenJDK 2D-Dev] RFR: JDK-8215296 do not disable c99 on Solaris

David Holmes david.holmes at oracle.com
Mon Dec 17 22:02:16 UTC 2018 

Hi Matthias,

On 17/12/2018 11:12 pm, Baesken, Matthias wrote:
> 
> Hello,  please review
> 
> http://cr.openjdk.java.net/~mbaesken/webrevs/8215296.0/
> 
> in my change just -xc99=%none  is removed, so we do not forbid c99 coding.
> 
> The -Xa compile flag is kept,  no special additional settings are needed to compile png/awt .

It's not at all clear to me that C99-isms will be allowed if -Xa is set.

I don't think jdk-submit tests Solaris. I'm putting this through our 
internal builds.

Thanks,
David

> 
> Thanks, Matthias
> 
> 
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Fri, 14 Dec 2018 15:39:26 +0100
>> From: Magnus Ihse Bursie <magnus.ihse.bursie at oracle.com>
>> To: Erik Joelsson <erik.joelsson at oracle.com>, build-dev
>> 	<build-dev at openjdk.java.net>, "awt-dev at openjdk.java.net"
>> 	<awt-dev at openjdk.java.net>, 2d-dev <2d-dev at openjdk.java.net>
>> Subject: Re: [OpenJDK 2D-Dev] RFR: JDK-8215296 do not disable c99 on
>> 	Solaris
>> Message-ID: <5874d10e-db2d-8681-a54b-a1eeb6e45994 at oracle.com>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>>
>>
>> On 2018-12-14 12:49, Magnus Ihse Bursie wrote:
>>>
>>> 13 dec. 2018 kl. 19:07 skrev Erik Joelsson <erik.joelsson at oracle.com
>>> <mailto:erik.joelsson at oracle.com>>:
>>>
>>>>
>>>> On 2018-12-13 02:11, Magnus Ihse Bursie wrote:
>>>>>
>>>>>> -D_XPG6
>>>>>>
>>>>>> ??
>>>>> To be honest, I'm not completely sure about this. Without this
>>>>> define, the build failed with the following error message:
>>>>> Compiler or options invalid for pre-UNIX 03 X/Open applications and
>>>>> pre-2001 POSIX applications
>>>>>
>>>>> This was triggered by the following section in
>>>>> /usr/include/sys/feature_tests.h:
>>>>> /*
>>>>>   * It is invalid to compile an XPG3, XPG4, XPG4v2, or XPG5 application
>>>>>   * using c99.  The same is true for POSIX.1-1990, POSIX.2-1992,
>>>>> POSIX.1b,
>>>>>   * and POSIX.1c applications. Likewise, it is invalid to compile an
>>>>> XPG6
>>>>>   * or a POSIX.1-2001 application with anything other than a c99 or
>>>>> later
>>>>>   * compiler.  Therefore, we force an error in both cases.
>>>>>   */
>>>>> #if defined(_STDC_C99) && (defined(__XOPEN_OR_POSIX) &&
>>>>> !defined(_XPG6))
>>>>> #error "Compiler or options invalid for pre-UNIX 03 X/Open
>>>>> applications \
>>>>>          and pre-2001 POSIX applications"
>>>>> #elif !defined(_STDC_C99) && \
>>>>>          (defined(__XOPEN_OR_POSIX) && defined(_XPG6))
>>>>> #error "Compiler or options invalid; UNIX 03 and POSIX.1-2001
>>>>> applications \
>>>>>          require the use of c99"
>>>>> #endif
>>>>>
>>>>> The solution, as also hinted to by searching for other resolutions
>>>>> to this error online, was to provide the _XPG6 system define. But
>>>>> exactly how we end up in feature_tests.h with __XOPEN_OR_POSIX set,
>>>>> without _XPG6 set, and only when compiling this library and not
>>>>> others, I don't know. I also don't understand what the XPG standard
>>>>> refers to, nor what versions 2-5 means or what version 6 has that
>>>>> differs from them.
>>>>>
>>>>> By setting this flag, I am telling solaris include headers that we
>>>>> want to compile using the XPG standard version 6, instead of an
>>>>> older one. It solves the problem. I am happy enough with this. Are you?
>>>>>
>>>> It looks like this comes from libpng. It has this in
>>>> src/java.desktop//share/native/libsplashscreen/libpng/pngpriv.h:
>>>>
>>>> /* Feature Test Macros.  The following are defined here to ensure
>>>> that correctly
>>>>   * implemented libraries reveal the APIs libpng needs to build and
>>>> hide those
>>>>   * that are not needed and potentially damaging to the compilation.
>>>>   *
>>>>   * Feature Test Macros must be defined before any system header is
>>>> included (see
>>>>   * POSIX 1003.1 2.8.2 "POSIX Symbols."
>>>>   *
>>>>   * These macros only have an effect if the operating system supports
>>>> either
>>>>   * POSIX 1003.1 or C99, or both.  On other operating systems
>>>> (particularly
>>>>   * Windows/Visual Studio) there is no effect; the OS specific tests
>>>> below are
>>>>   * still required (as of 2011-05-02.)
>>>>   */
>>>> #ifndef _POSIX_SOURCE
>>>> # define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
>>>> #endif
>>>>
>>>> This in turn triggers _XOPEN_OR_POSIX to be defined in
>>>> /usr/include/sys/feature_tests.h and so triggers the error.
>>>>
>>>> What I'm not clear about is if libpng is trying to declare that it
>>>> should not be compiled with any newer standards, and so by doing
>>>> that, we risk introducing problems. Reading in the system header, it
>>>> seems the _XPG6 macro is internal and should not be used by the
>>>> application. It's derived from _XOPEN_SOURCE=600 or
>>>> _POSIX_C_SOURCE=200112L which is what applications should use.
>>>
>>> Interesting. We should probably define one, or both of these. Perhaps
>>> globally for all native files and compilers. It might have been the
>>> case that the solstudio compiler set _POSIX_C_SOURCE for us before,
>>> prior to setting -std=c99. The following stack overflow article claims
>>> that this is at least the behavior of gcc/clang:
>>>
>>> https://stackoverflow.com/questions/21867897/c89-and-posix-at-the-
>> same-time
>>>
>>>
>>> So we might have had an implicit _POSIX_C_SOURCE that we now miss.
>>> That would explain why this starts to fail. I'll see if I can confirm
>>> this the next time I log into a Solaris computer.
>> Of course it was not as simple. Setting:
>>     ifeq ($(OPENJDK_TARGET_OS), solaris)
>>       LIBSPLASHSCREEN_CFLAGS += -D_POSIX_C_SOURCE=200112L -
>> D_XOPEN_SOURCE=600
>>     endif
>>
>> instead made us fail with:
>> open/src/java.desktop/unix/native/libsplashscreen/splashscreen_sys.c",
>> line 143: error: incomplete struct/union/enum timezone: tz
>>
>> I don't have more time to dig into this now. Overall, changes such as
>> these make it all feel a bit scary; I recommend that any change to this
>> be made in JDK 13 and not 12.
>>
>> /Magnus
>>>
>>> Otoh, the same article claims, and it sounds reasonable, that we
>>> should set these variables ourself, to be well behaved and to minimize
>>> surprises. And I think this applies to all unix platforms, regardless
>>> of compiler being used. I'll see if I can kick off a test job with
>>> this to see how/if it influences other platforms. But it sounds like
>>> something we should do; the level of posix conformance should be
>>> controlled by us, not left to chance. We also need to verify, of
>>> course, that all platforms we want to support is capable of
>>> supporting  _POSIX_C_SOURCE=200112L. I doubt there's a problem
>> though.
>>> Possibly on AIX...
>>>
>>> /Magnus
>>>
>>>>
>>>> So the the question is, is it ok to override the requirements of
>>>> libpng or should it receive special treatment? If we are fine with
>>>> overriding, then we should use one of the public APIs instead.
>>>>
>>>> /Erik
>>>>
>>>>> /Magnus
>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> David
>>>>>>
>>>>>> On 13/12/2018 7:02 am, Magnus Ihse Bursie wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 2018-12-12 20:08, Magnus Ihse Bursie wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2018-12-12 19:12, Magnus Ihse Bursie wrote:
>>>>>>>>>  From the bug report:
>>>>>>>>> "Currently  we disable C99 in the Solaris build by setting
>>>>>>>>> -xc99=%none%.
>>>>>>>>> This differs from a lot of other build environments like
>>>>>>>>> gcc/Linux or VS2013/2017 on Windows where C99 features work.
>>>>>>>>> We should remove this difference on Solaris and remove or
>>>>>>>>> replace the setting.
>>>>>>>>>
>>>>>>>>> Kim Barrett mentioned :
>>>>>>>>> "I merely mentioned the C++14 work as evidence that removing
>>>>>>>>> -xc99=%none% didn?t appear harmful."
>>>>>>>>> However it will take more time until  the C++14 change is in."
>>>>>>>>>
>>>>>>>>> I am currently running a test build on our CI build system to
>>>>>>>>> confirm that this does not break the Solaris build (but I'd be
>>>>>>>>> highly surprised if it did). I will not push this until the
>>>>>>>>> builds are cleared.
>>>>>>>> Of course it was not that simple... :-( Two AWT libraries (at
>>>>>>>> least) failed to build. I'm currently investigating if there's a
>>>>>>>> simple fix to that.
>>>>>>> New attempt, that fixes the two AWT libraries:
>>>>>>> WebRev:
>>>>>>> http://cr.openjdk.java.net/~ihse/JDK-8215296-build-solstudio-with-
>> c99/webrev.01
>>>>>>> <http://cr.openjdk.java.net/%7Eihse/JDK-8215296-build-solstudio-
>> with-c99/webrev.01>
>>>>>>>
>>>>>>>
>>>>>>> Now this passes the CI build test.
>>>>>>>
>>>>>>> /Magnus
>>>>>>>>
>>>>>>>> /Magnus
>>>>>>>>>
>>>>>>>>> /Magnus
>>>>>>>>>
>>>>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8215296
>>>>>>>>> Patch inline:
>>>>>>>>> diff --git a/make/autoconf/flags-cflags.m4
>>>>>>>>> b/make/autoconf/flags-cflags.m4
>>>>>>>>> --- a/make/autoconf/flags-cflags.m4
>>>>>>>>> +++ b/make/autoconf/flags-cflags.m4
>>>>>>>>> @@ -559,7 +559,7 @@
>>>>>>>>> TOOLCHAIN_CFLAGS="-errshort=tags"
>>>>>>>>>
>>>>>>>>> TOOLCHAIN_CFLAGS_JDK="-mt $TOOLCHAIN_FLAGS"
>>>>>>>>> - TOOLCHAIN_CFLAGS_JDK_CONLY="-xc99=%none -xCC -Xa -W0,-
>> noglobal
>>>>>>>>> $TOOLCHAIN_CFLAGS" # C only
>>>>>>>>> + TOOLCHAIN_CFLAGS_JDK_CONLY="-std=c99 -xCC -W0,-noglobal
>>>>>>>>> $TOOLCHAIN_CFLAGS" # C only
>>>>>>>>> TOOLCHAIN_CFLAGS_JDK_CXXONLY="-features=no%except -
>> norunpath
>>>>>>>>> -xnolib" # CXX only
>>>>>>>>> TOOLCHAIN_CFLAGS_JVM="-template=no%extdef -
>> features=no%split_init \
>>>>>>>>>           -library=stlport4 -mt -features=no%except
>>>>>>>>> $TOOLCHAIN_FLAGS"
>>>>>>>>
>>>>>>>
>>>>>
>>
>

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