Can't use shared_library in custom_target command

[copelnug]

Example

foo_lib = shared_library(...)
custom_target('foo.dll.debug',
build_by_default: true,
command: [python3, extractDebugScript, foo_lib],
output: [libfoo.so.debug]
)

Error

Traceback (most recent call last):
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\mesonmain.py", line 112, in run
return options.run_func(options)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\msetup.py", line 230, in run
app.generate()
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\msetup.py", line 161, in generate
self._generate(env)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\msetup.py", line 210, in _generate
intr.backend.generate(intr)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\backend\ninjabackend.py", line 225, in generate
self.generate_target(t, outfile)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\backend\ninjabackend.py", line 326, in generate_target
self.generate_custom_target(target, outfile)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\backend\ninjabackend.py", line 508, in generate_custom_target
(srcs, ofilenames, cmd) = self.eval_custom_target_command(target)
File "c:\program files (x86)\python36-32\lib\site-packages\mesonbuild\backend\backends.py", line 893, in eval_custom_target_command
raise RuntimeError(err_msg.format(str(i), str(type(i))))
RuntimeError: Argument <SharedLibrary 25a6634@@foo@sha: foo.dll> is of unknown type <class 'mesonbuild.build.SharedLibrary'>

Workaround

It is necessary to use foo_lib.full_path() instead. This is different than what work for executable.
Also, foo_lib should be added to depends of custom_target.

[QuLogic]

You should pass it using @INPUT@, I believe:

custom_target('foo.dll.debug',
  build_by_default: true,
  command: [python3, extractDebugScript, '@INPUT@'],
  input: foo_lib,
  output: 'libfoo.so.debug'
)

[mikezackles]

@QuLogic Your suggestion didn't work for me. The only thing that worked was something like

custom_target('foo.dll.debug',
  build_by_default: true,
  command: [python3, extractDebugScript, foo_lib.full_path()],
  input: foo_lib,
  output: 'libfoo.so.debug'
)

[martinpitt]

This is a special case of #1848. I also found this via trying to build a .typelib for a shared library (issue #5968). As mentioned in #2296, #1848 or #5968, the documented example of using a built file as custom_target input: does not work. I get that, using "file objects" for that makes conceptual sense, even though it's quite a paradigm shift when coming from make where the file names are the primary objects to work with.

But then there's still an impedance mismatch: shared_library() does have four outputs, but (1) it is rather hard to see them -- the only way I found was to drop one of the arguments in install_dir: [true, true, true, true]), and read them from the error message:

ERROR: Target 'umockdev' has 4 outputs: ['libumockdev.so.0.3.0', 'umockdev.h', 'umockdev-1.0.vapi', 'UMockdev-1.0.gir'], but only 3 "install_dir"s were found.

Then I would expect to do something like this:

umockdev_lib = shared_library(...)

custom_target('UMockdev-1.0 typelib',
  command: [g_ir_compiler, '--output', '@OUTPUT@', '-l', 'libumockdev.so.0', '@INPUT@'],
  input: umockdev_lib[3],
  output: 'UMockdev-1.0.typelib',
  install: true,
  install_dir: get_option('libdir') / 'girepository-1.0')

But that doesn't work:

../meson.build:114:0: ERROR: Tried to index an object that doesn't support indexing.

I also tried to put the indexing into the command line:

  command: [g_ir_compiler, '--output', '@OUTPUT@', '-l', 'libumockdev.so.0', '@INPUT3@'],
  input: umockdev_lib,

but that doesn't work either:

ERROR: Command cannot have '@INPUT3@' since there are only 1 inputs

i. e. you only see the built .so, not the auxiliary outputs (.gir, .h and so on).

So I think this amounts to a design decision: Does meson want to chain builds with file objects or file names? In the former case, please provide proper output objects, in the latter case, re-enable input: 'filename' if filename is the output of some other rule.

Thanks!

[jpakkane]

Any particular reason why you are building typelibs by hand rather than using the builtins in the Gnome module?

[martinpitt]

@jpakkane : The Compiling Vala applications and libraries documentation says to use custom_target() (That documentation does not work due to said input: meson.current_build_dir() / 'Foo-1.0.gir', but at least to me the most obvious way how to fix it was to avoid input:.). I wasn't even aware of gnome.generate_dir(), thanks!

But also, (1) I need to post-process the .gir as Vala does not support explicit annotations (I need a Rename-to:), and (2) generate_dir() seems to be tailored towards a C library. My library is written in vala, and valac already generates the .gir file -- I just need to build the .typelib for it.