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

Baesken, Matthias matthias.baesken at sap.com
Mon Dec 17 13:12:12 UTC 2018 

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 .


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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