Help needed with gobject-introspection

Ken Brown kbrown@cornell.edu
Mon May 25 15:04:14 GMT 2020


On 5/24/2020 1:00 PM, Ken Brown via Cygwin-apps wrote:
> On 5/24/2020 12:45 PM, Ken Brown via Cygwin-apps wrote:
>> On 5/24/2020 11:56 AM, Jon Turney wrote:
>>> On 21/05/2020 18:07, Ken Brown via Cygwin-apps wrote:
>>>> On 5/21/2020 11:48 AM, Jon Turney wrote:
>>>>> On 21/05/2020 16:13, Ken Brown via Cygwin-apps wrote:
>>>>>> On 5/21/2020 9:24 AM, Jon Turney wrote:
>>>>>>> On 20/05/2020 15:50, Ken Brown via Cygwin-apps wrote:
>>>>>>>> On 5/19/2020 7:04 PM, Ken Brown via Cygwin-apps wrote:
>>>>>>>>> I would like to adopt gimp and related packages.  At the moment I'm 
>>>>>>>>> having trouble with babl, which is needed for gegl0.4, which is needed 
>>>>>>>>> for gimp. The problem involves gobject-introspection.
>>>>>>>>>
>>>>>>>>> If I disable introspection, the build works fine.  This would be OK, 
>>>>>>>>> since babl has been built without introspection for several years. But 
>>>>>>>>> then the gegl0.4 build complains about the missing babl introspection 
>>>>>>>>> files, so I would have to disable introspection there too, which hasn't 
>>>>>>>>> been done in the past.
>>>>>>>>>
>>>>>>>>> So my preference is to figure out what the problem is and get the babl 
>>>>>>>>> build working with introspection.  I'm attaching my cygport file and 
>>>>>>>>> patch.
>>>>>>>>>
>>>>>>>>> Here's the failing command...
>>>>>>>>>
>>>>>>>>> /usr/bin/g-ir-scanner -I/usr/include/gobject-introspection-1.0 
>>>>>>>>> -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -D_REENTRANT 
>>>>>>>>> --no-libtool --namespace=Babl --nsversion=0.1 --warn-all --output 
>>>>>>>>> babl/Babl-0.1.gir --c-include=babl.h 
>>>>>>>>> '--identifier-filter-cmd=/usr/bin/python3 
>>>>>>>>> /tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/babl/identfilter.py' 
>>>>>>>>> -DBABL_IS_BEING_COMPILED 
>>>>>>>>> -I/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/babl 
>>>>>>>>> -I/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl 
>>>>>>>>> -I./. -I../. -I./babl/base/. -I../babl/base/. 
>>>>>>>>> --filelist=/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl/4170c83@@babl-0.1@sha/Babl_0.1_gir_filelist 
>>>>>>>>> --cflags-begin -fno-unsafe-math-optimizations 
>>>>>>>>> -Wdeclaration-after-statement -Winit-self -Wmissing-declarations 
>>>>>>>>> -Wmissing-prototypes -Wold-style-definition -Wpointer-arith -mmmx -msse 
>>>>>>>>> -mfpmath=sse -I./. -I../. -I./babl/base/. -I../babl/base/. --cflags-end 
>>>>>>>>> --library babl-0.1 
>>>>>>>>> -L/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl 
>>>>>>>>> --extra-library=m --extra-library=dl --extra-library=lcms2
>>>>>>>>>
>>>>>>>>> ...and the error message:
>>>>>>>>>
>>>>>>>>> g-ir-scanner: link: gcc -o 
>>>>>>>>> /tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/tmp-introspectCwCaUc/Babl-0.1.exe 
>>>>>>>>> -ggdb -O2 -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 
>>>>>>>>> -fstack-protector-strong --param=ssp-buffer-size=4 
>>>>>>>>> -fdebug-prefix-map=/tmp/cygbabl/babl-0.1.74-1.x86_64/build=/usr/src/debug/babl-0.1.74-1 
>>>>>>>>> -fdebug-prefix-map=/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74=/usr/src/debug/babl-0.1.74-1 
>>>>>>>>> /tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/tmp-introspectCwCaUc/Babl-0.1.o 
>>>>>>>>> -L. -lbabl-0.1 -lm -ldl -llcms2 
>>>>>>>>> -L/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl 
>>>>>>>>> -Wl,-rpath,/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl 
>>>>>>>>> -lgio-2.0 -lgobject-2.0 -Wl,--export-all-symbols -lgmodule-2.0 
>>>>>>>>> -lglib-2.0 -lintl
>>>>>>>>> ERROR: can't resolve libraries to shared libraries: babl-0.1
>>>>>>>>>
>>>>>>>>> I don't understand the error message, because the command line contains
>>>>>>>>>
>>>>>>>>> -L/tmp/cygbabl/babl-0.1.74-1.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/babl
>>>>>>>>>
>>>>>>>>> and that directory contains libbabl-0.1.dll.a and cygbabl-0.1-0.dll. I 
>>>>>>>>> even tried adding that directory to my PATH to make sure the right 
>>>>>>>>> cygbabl-0.1-0.dll would be found, but that didn't help.
>>>>>>>
>>>>>>> This might possibly be related to the problem described in the comment for:
>>>>>>>
>>>>>>> https://github.com/mesonbuild/meson/pull/2880/commits/8a27c08b05e4537d5061d30ddd8aad9dc52cf1c4 
>>>
>>>
>>>
>>>
>>> Yeah, this looks extremely plausible, there seem to be no GObject derived 
>>> types in babl's interface.
>>>
>>> It might be possible to work around this by patching in a dummy GObject 
>>> derived type which does nothing.
>>>
>>> I'll have to see if I can find my notes about how I debugged this before.
>>>
>>>>>>>> By the way, in case you're wondering why I disabled the building of 
>>>>>>>> docs, it's because I was getting a build failure there too.  I don't 
>>>>>>>> know if this is related to the introspection failure.  The failing 
>>>>>>>> command there is
>>>>>>>>
>>>>>>>> /usr/bin/meson --internal exe --unpickle 
>>>>>>>> /tmp/cygbabl/babl-0.1.74-2.x86_64/src/babl-0.1.74/x86_64-pc-cygwin/meson-private/meson_exe_env_7bf39b99114d34540b83d26a5d8f097e05882836.dat 
>>>>>>>>
>>>>>>>> cp: target 'docs/index.html.tmp' is not a directory
>>>>>>>>
>>>>>>>> I don't know why it's not showing me the actual cp command that fails. 
>>>>>>>
>>>>>>> I believe it's is an infelicity in meson that it doesn't echo the actual 
>>>>>>> failing command here.
>>>>>>>
>>>>>>> Noted here: 
>>>>>>> https://github.com/mesonbuild/meson/pull/3716#issuecomment-395746838
>>>>>>>
>>>>>>>> The corresponding information in docs/meson.build is
>>>>>>>>
>>>>>>>> Reference_html = custom_target('Reference.html',
>>>>>>>>    input : [
>>>>>>>>      'Reference-static.html',
>>>>>>>>      'toc',
>>>>>>>>      index_html_tmp,
>>>>>>>>    ],
>>>>>>>>    output: [ 'Reference.html', ],
>>>>>>>>    command: [
>>>>>>>>      env_bin,
>>>>>>>>      'cp', '@INPUT0@', '@OUTPUT@',
>>>>>>>>      '&&', xml_insert, '@OUTPUT@', 'TOC', '@INPUT1@',
>>>>>>>>      '&&', xml_insert, '@OUTPUT@', 'BablBase', '@INPUT2@',
>>>>>>>>    ],
>>>>>>>>    build_by_default: true,
>>>>>>>> )
>>>>>>>>
>>>>>>>> There are several such custom targets in the file, and for all except 
>>>>>>>> this one, I see the actual cp command in the log.  This is the only one 
>>>>>>>> for which meson generates a 'meson --unpickle' command instead of a cp 
>>>>>>>> command.
>>>>>>>
>>>>>>> Yeah, I wasn't expecting it to use this method of executing the command 
>>>>>>> line (storing it in a pickle and then using a python wrapper to execute 
>>>>>>> it) to be used except on Windows, so I'll have to take a more detailed 
>>>>>>> look at why that's happening.
>>>
>>> So, it's correct that it runs this command indirectly via the pickle, because 
>>> it needs to interpose itself to do some PATH manipulation to add the DLL, 
>>> because this target has the 'babl-html-dump' tool, which is linked with the 
>>> DLL, in it's input (indirectly).
>>>
>>>>>> Thanks.  FWIW, the recipe for building docs/Reference.html translates to
>>>>>>
>>>>>>    /usr/bin/env \
>>>>>>       cp ../docs/Reference-static.html docs/Reference.html \
>>>>>>        && ../docs/tools/xml_insert.sh docs/Reference.html TOC ../docs/toc \
>>>>>>        && ../docs/tools/xml_insert.sh \
>>>>>>           docs/Reference.html BablBase docs/index.html.tmp
>>>>>>
>>>>>> This succeeds when run manually in the build directory.  So something must 
>>>>>> have gone wrong in the pickling/unpickling process.
>>>>>
>>>>>
>>>>> patching /usr/lib/python3.6/site-packages/mesonbuild/scripts/meson_exe.py 
>>>>> something like this might shed some light:
>>>>>
>>>>> --- meson_exe.py.bak    2020-05-21 15:01:19.187046500 +0100
>>>>> +++ meson_exe.py        2020-05-21 15:09:29.485915300 +0100
>>>>> @@ -57,6 +57,8 @@
>>>>>                   ['Z:' + p for p in exe.extra_paths] + 
>>>>> child_env.get('WINEPATH', '').split(';')
>>>>>               )
>>>>>
>>>>> +    print(cmd_args)
>>>>> +
>>>>>       p = subprocess.Popen(cmd_args, env=child_env, cwd=exe.workdir,
>>>>>                            close_fds=False,
>>>>>                            stdout=subprocess.PIPE,
>>>>
>>>> OK, now the log shows
>>>>
>>>> cp: target 'docs/index.html.tmp' is not a directory
>>>> ['/usr/bin/env', 'cp', '../docs/Reference-static.html', 
>>>> 'docs/Reference.html', '&&', 
>>>> '/home/kbrown/src/cygpackages/babl/babl-0.1.74-1.x86_64/src/babl-0.1.74/docs/tools/xml_insert.sh', 
>>>> 'docs/Reference.html', 'TOC', '../docs/toc', '&&', 
>>>> '/home/kbrown/src/cygpackages/babl/babl-0.1.74-1.x86_64/src/babl-0.1.74/docs/tools/xml_insert.sh', 
>>>> 'docs/Reference.html', 'BablBase', 'docs/index.html.tmp']
>>>>
>>>> This does indeed shed some light.  If I remove all the commas but leave the 
>>>> single quotes, the command fails with the same error message as before:
>>>>
>>>> cp: target 'docs/index.html.tmp' is not a directory
>>>>
>>>> If I also remove the single quotes, the command succeeds.  I think the 
>>>> problem is the quotes around the double ampersands, so they are treated as 
>>>> arguments to the cp command instead of being interpreted by the shell 
>>>> executing the command.
>>>
>>> So, yeah, this is a meson bug, which I will work on (if this command ends up 
>>> in the build.ninja, it's executed by ninja with 'sh -c', but if it ends up in 
>>> a pickle, it's executed by meson with execve())
>>
>> Yes, that does seem like a meson bug.  But is it also a babl bug to some 
>> extent?   When babl puts '&&' in a command argument, it's assuming that the 
>> command will be executed by 'sh -c'.
>>
>> I have very little experience with meson.  Have you ever seen this issue in 
>> other projects that use meson?
> 
> I just noticed this, at https://mesonbuild.com/Custom-build-targets.html :
> 
>    Meson only permits you to specify one command to run. This is
>    by design as writing shell pipelines into build definition
>    files leads to code that is very hard to maintain. If your
>    compilation requires multiple steps you need to write a wrapper
>    script that does all the necessary work.
> 
> We're not talking about a shell pipeline here, but it's similar.  So I'm 
> thinking this really is a babl bug.

Regardless of whose bug it is, I've got a simple but ugly workaround (attached), 
now that you've explained to me what's going on.

Ken
-------------- next part --------------
--- origsrc/babl-0.1.74/docs/meson.build	2020-01-12 18:26:51.000000000 -0500
+++ src/babl-0.1.74/docs/meson.build	2020-05-24 22:10:24.081359400 -0400
@@ -54,22 +54,26 @@ index_html = custom_target('index.html',
   build_by_default: true,
 )
 
-Reference_html = custom_target('Reference.html',
+Reference_html_tmp = custom_target('Reference.html.tmp',
   input : [
     'Reference-static.html',
     'toc',
-    index_html_tmp,
   ],
-  output: [ 'Reference.html', ],
+  output: [ 'Reference.html.tmp', ],
   command: [
     env_bin,
     'cp', '@INPUT0@', '@OUTPUT@',
     '&&', xml_insert, '@OUTPUT@', 'TOC', '@INPUT1@',
-    '&&', xml_insert, '@OUTPUT@', 'BablBase', '@INPUT2@',
   ],
-  build_by_default: true,
 )
 
+Reference_html = custom_target('Reference.html',
+  input : [ Reference_html_tmp, index_html_tmp, ],
+  output: [ 'Reference.html', ],
+  command: [ xml_insert, '@INPUT0@', 'BablBase', '@INPUT1@', 'cat_result' ],
+  build_by_default: true,
+  capture: true,
+)
 
 CMYK_html = custom_target('CMYK.html',
   input : [
--- origsrc/babl-0.1.74/docs/tools/xml_insert.sh	2020-01-12 18:26:51.000000000 -0500
+++ src/babl-0.1.74/docs/tools/xml_insert.sh	2020-05-25 07:54:31.875472500 -0400
@@ -7,6 +7,9 @@
 #
 # xml_insert.sh bar.xml foo foo.inc
 #
+# If there's a fourth argument, cat the final result.
+#
+#
 # 2005 © Øyvind Kolås
 #
 # FIXME: add argument checking / error handling
@@ -97,6 +100,9 @@ tailno=`expr $numlines - $splitno`
 head -$splitno $tmp_file > $1
 cat $3 >> $1
 tail -$tailno $tmp_file >> $1
+if test -n "$4"; then
+  cat $1
+fi
 
 rm -rf $tmp_dir
 


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