Hi

I've just pushed a "scons-build" branch.

The build infrastructure is in main/scons. Python and SCons have to be
installed system-wide and available in $PATH. Currently we require Python
3, but that's easy to change.

So far main/fileaccess has been converted to SCons as a test. Its gbuild
files are still there; prj/makefile.mk determines whether to use gbuild or
scons. SCons is only used at a module level, build.pl is still the
launcher. You can build main/fileaccess in isolation by running "scons"
inside main/, or "scons -u" inside main/fileaccess, and clean by adding
"-c" (or "--clean") to those flags. It will correctly build the .cxx file,
link it into a library, install the library, run xsltproc on the .component
file, install the transformed .component file, and install the .xml file.
Everything can also be successfully cleaned.

At present FreeBSD has been tested, and I will test Windows soon. Other
platforms don't exist, and still have to be added in
main/site_scons/platform.

The converter is in gotoGBuild/, at the same level as main/ and test/. You
build it with Maven by running "mvn package". Then:

java -cp target/classes org.apache.openoffice.gotoSCons.GBuildConverter
parsingAnalysis ../main
Attempts to parse each gbuild module, printing out errors for those that
couldn't be, and a summary of which could be parsed.
What is also useful is:
java -cp target/classes org.apache.openoffice.gotoSCons.GBuildConverter
parsingAnalysis ../main 2>&1 | grep java.lang.Exception >
/tmp/errorsByModule.csv
Then open /tmp/errorsByModule.csv in AOO, use # as the field separator, and
you get a table of modules that failed and a reason for each one. Sort by
column B, and you can see how often a reason occurs, for example 21 modules
need AllLangResTarget implemented. That can inform further development.

To actually convert a module to SCons, use one of the modules that previous
results said could be parsed, eg. io, and run:
java -cp target/classes org.apache.openoffice.gotoSCons.GBuildConverter
parseModule ../main/io/Module_io.mk
It will print the converted SCons file to standard output.

Converting library names is currently broken. In main/fileaccess and
main/site_scons I've begun with dmake's way of naming libraries, like in
main/solenv/inc/libs.mk. GBuild re-did library naming by using 10
layer-specific rules, and then having tons of exceptions in
main/RepositoryFixes.mk; I am not sure which is worse. Maybe we should give
up the pretense, and just have a table in a CSV file, with platforms as
column headers, and library names as row headers, with the
platform-specific name in each field, and parse it with Python's built-in
CSV package on build startup?



On Sat, Feb 1, 2020 at 8:10 PM Peter Kovacs <pe...@apache.org> wrote:

> Hi Damjan,
>
> Let's try it. But I suggest to push to an own branch. There is no worth in
> trying and getting stuck in the same spot.
>
> Merge is done quickly. And it is great if others can have a look, too.
>
> All the best
> Peter
>
>
> Am 1. Februar 2020 13:36:42 MEZ schrieb Damjan Jovanovic <
> dam...@apache.org>:
> >Hi
> >
> >gbuild has become an unmaintainable nightmare. While there are only 37
> >internal dmake modules left (+ another 37 external modules), I cannot
> >motivate myself to convert even 1 more. At my development speed of
> >about 2
> >lines of code every 8 hours, gbuild is a disaster that wastes
> >unbelievable
> >amounts of time, and it's really not a development I can say I am proud
> >of.
> >It has the ugliest syntax ever, it can only be debugged through
> >experimentation, and nobody really understands it. Also, it doesn't
> >fully
> >work, eg. a lot of the newer targets I've added don't get cleaned on
> >"make
> >clean", CustomTarget fails to deliver files sometimes, etc.
> >
> >To that end, I've restarting playing with an old idea: to switch to the
> >SCons build system, using a tool to automatically convert build files
> >from
> >gbuild to SCons.
> >
> >I got my previous scons build (of 1 module) up and running very
> >quickly,
> >and it still works. Then I continued development of my gbuild parser
> >and
> >automated converter, which I've called gotoSCons, and got it to parse
> >most
> >of the build instructions in Module_xxx.mk, Library_xxx.mk,
> >Executable_xxx.mk and Package_xxx.mk and convert them to a SCons build
> >file
> >(SConscript).
> >
> >gotoSCons is relatively simple, about 1200 lines of Java, and I can
> >provide
> >it to interested parties, or put it in a Git branch. It already found 3
> >bugs in these gbuild files:
> >1. main/xmloff/Package_inc.mk duplicates this line:
> >$(eval $(call
>
> >gb_Package_add_file,xmloff_inc,inc/xmloff/XMLTextShapeImportHelper.hxx,xmloff/XMLTextShapeImportHelper.hxx))
> >I've committed a fix in 85bfc14eebba4af4847075b1cf1eaecfa87bcfc4
> >2. main/bean/Module_bean.mk adds no targets.
> >3. main/testgraphical/Module_testgraphical.mk does nothing.
> >
> >The gotoSCons parser is very strict, it tries hard to guarantee a
> >correct
> >conversion, and will immediately fail on non-deterministic sections,
> >such
> >as "ifeq ($(OS),WNT)". It will also immediately fail on deliverable
> >types
> >that I haven't implemented yet, such as AllLangResTarget_,
> >StaticLibrary_
> >etc., and commands within targets that I haven't implemented yet such
> >as
> >gb_Executable_set_targettype_gui and gb_Library_use_externals. Out of
> >our
> >total of 105 gbuild modules, 53 use non-deterministic sections, and
> >will
> >require some degree of manual conversion, but the converter should
> >eventually be able to handle the other 52 modules. Even with the
> >limited
> >deliverable/command support at present, it can successfully convert 19
> >modules. The conversion would be straightforward even if done manually,
> >as
> >both gbuild and SCons are high level build systems with similar
> >concepts:
> >includes, defines, cflags, libraries to link to, and so on (dmake is
> >the
> >difficult low-level tool).
> >
> >I love SCons. It's been easy integrating it into our build. It just
> >works.
> >It has beautiful clear syntax. It's understandable and debuggable. It
> >makes
> >development fun again. It's a well established build system, with a 20
> >year
> >history, supporting Python 2 and 3, supporting almost every platform
> >out
> >there including OS/2, supporting every version of MSVC including Visual
> >Studio 2019, supporting advanced features like ELF sonames, library
> >version
> >symlinks and library name prefixes and suffixes, flex and bison targets
> >(which we all need), automatically generating cleaning targets for
> >every
> >build target, can use checksums instead of timestamps to avoid
> >unnecessary
> >rebuilds, automatic header dependency extraction, can build a module by
> >itself instead of the whole project, parallelizes building at a file
> >level
> >(across module boundaries). It can build at least some AOO modules
> >without
> >Cygwin. It is easy to add custom targets, unlike gbuild where it's
> >almost
> >impossible. It is equal to or better than gbuild in just about
> >everything,
> >and we don't have to maintain it going forward like we do with gbuild:
> >its
> >developers develop it, and we just use it.
> >
> >If someone would like to get involved, please let me know soon, so we
> >can
> >decide on an API, file layout, etc. before I've begun committing any
> >changes (and relax, they would be committed to a separate branch until
> >we
> >are convinced it works well).
> >
> >I was the major force that led us into more gbuild, but now I think
> >it's
> >time to leave it. It's already coming apart at the seams, and I don't
> >see
> >it being developed further. It's based on ($eval), an optional extra
> >added
> >quite late, as an afterthought for special cases, probably not how GNU
> >make
> >was intended to be used at scale, and a feature absent in other
> >"make"s.
> >The only other project in the world that uses gbuild is LO, and I
> >recall
> >reading how it took them an enormous amount of work to migrate to it
> >fully.
> >Let's learn from their mistake?
> >
> >Regards
> >Damjan
>

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