I got this warning on a build:
> WARNING: Passed invalid keyword argument preset. This will become a hard error in the future.
I had to grep in meson code to understand that "preset" was the name of
the invalid argument. This is not obvious at all depending on the
argument name (here it looked like it was about argument presets).
Let's make it clearer by putting it in quotes.
While g-ir-scanner's compatible -I and -D flags cover what most dependencies
use, there's no guarantee that a dependency's cflags don't include more
exotic flags that conflict with the tool's own options.
For a real world example, mozjs-38 has '-include some-header-file.h', which
translates to '--include nclude another-file-to-scan.h' for the scanner;
unless for some reason there's an 'nclude' GIR available on the system,
the target will thus fail.
For this purpose, g-ir-scanner allows explicitly marking some flags as
preprocessor/compiler flags by guarding them with --cflags-begin and
--cflags-end. Make sure it is used this for all cflags, not only for
global and project flags.
This class now consolidates a lot of the logic that each external
dependency was duplicating in its class definition.
All external dependencies now set:
* self.version
* self.compile_args and self.link_args
* self.is_found (if found)
* self.sources
* etc
And the abstract ExternalDependency class defines the methods that
will fetch those properties. Some classes still override that for
various reasons, but those should also be migrated to properties as
far as possible.
Next step is to consolidate and standardize the way in which we call
'configuration binaries' such as sdl2-config, llvm-config, pkg-config,
etc. Currently each class has to duplicate code involved with that
even though the format is very similar.
Currently only pkg-config supports multiple version requirements, and
some classes don't even properly check the version requirement. That
will also become easier now.
There are cases where we need to specify arguments to gtkdoc-mkdb, like
telling it to scan extensions that are not '.h' and '.c'. Let's add a
new named argument to gnome.gtkdoc(), as well as the plumbing needed for
the gtk-doc helper script.
Usage:
pkgconfig.generate(
...
description : 'A library with custom variables.',
variables : ['foo=bar', 'datadir=${prefix}/data']
)
The variables 'prefix', 'libdir' and 'includedir' are reserved, meson will
fail with an error message.
Variables can reference each other with the pkgconfig notation, e.g.
variables : ['datadir=${prefix}/data',
'otherdatadir=${datadir}/other']
meson does not check this for correctness or that the referenced variable
exists, we merely keep the same order as specified.
Meson has a common pattern of using 'if len(foo) == 0:' or
'if len(foo) != 0:', however, this is a common anti-pattern in python.
Instead tests for emptiness/non-emptiness should be done with a simple
'if foo:' or 'if not foo:'
Consider the following:
>>> import timeit
>>> timeit.timeit('if len([]) == 0: pass')
0.10730923599840025
>>> timeit.timeit('if not []: pass')
0.030033907998586074
>>> timeit.timeit('if len(['a', 'b', 'c', 'd']) == 0: pass')
0.1154778649979562
>>> timeit.timeit("if not ['a', 'b', 'c', 'd']: pass")
0.08259823200205574
>>> timeit.timeit('if len("") == 0: pass')
0.089759664999292
>>> timeit.timeit('if not "": pass')
0.02340641999762738
>>> timeit.timeit('if len("foo") == 0: pass')
0.08848102600313723
>>> timeit.timeit('if not "foo": pass')
0.04032287199879647
And for the one additional case of 'if len(foo.strip()) == 0', which can
be replaced with 'if not foo.isspace()'
>>> timeit.timeit('if len(" ".strip()) == 0: pass')
0.15294511600222904
>>> timeit.timeit('if " ".isspace(): pass')
0.09413968399894657
>>> timeit.timeit('if len(" abc".strip()) == 0: pass')
0.2023209120015963
>>> timeit.timeit('if " abc".isspace(): pass')
0.09571301700270851
In other words, it's always a win to not use len(), when you don't
actually want to check the length.
configure a detection method, for those types of dependencies that have
more than one means of detection.
The default detection methods are unchanged if 'method' is not
specified, and all dependencies support the method 'auto', which is the
same as not specifying a method.
The dependencies which do support multiple detection methods
additionally support other values, depending on the dependency.
When cross compiling with mingw it's problematic to assume that there is
a binary called windres, and having to set it via an environment
variable seems wrong when there is a handy cross-file for just such a
situation.
This patch allows setting windres in the [binaries] section of the cross
file. If the build is a cross build, then the windows module will check
for windres being set in the cross file before checking the WINDRES
environment variable or looking for a windres binary.
You can now pass a list of strings to the install_dir: kwarg to
build_target and custom_target.
Custom Targets:
===============
Allows you to specify the installation directory for each
corresponding output. For example:
custom_target('different-install-dirs',
output : ['first.file', 'second.file'],
...
install : true,
install_dir : ['somedir', 'otherdir])
This would install first.file to somedir and second.file to otherdir.
If only one install_dir is provided, all outputs are installed there
(same behaviour as before).
To only install some outputs, pass `false` for the outputs that you
don't want installed. For example:
custom_target('only-install-second',
output : ['first.file', 'second.file'],
...
install : true,
install_dir : [false, 'otherdir])
This would install second.file to otherdir and not install first.file.
Build Targets:
==============
With build_target() (which includes executable(), library(), etc),
usually there is only one primary output. However some types of
targets have multiple outputs.
For example, while generating Vala libraries, valac also generates
a header and a .vapi file both of which often need to be installed.
This allows you to specify installation directories for those too.
# This will only install the library (same as before)
shared_library('somevalalib', 'somesource.vala',
...
install : true)
# This will install the library, the header, and the vapi into the
# respective directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : ['libdir', 'incdir', 'vapidir'])
# This will install the library into the default libdir and
# everything else into the specified directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : [true, 'incdir', 'vapidir'])
# This will NOT install the library, and will install everything
# else into the specified directories
shared_library('somevalalib', 'somesource.vala',
...
install : true,
install_dir : [false, 'incdir', 'vapidir'])
true/false can also be used for secondary outputs in the same way.
Valac can also generate a GIR file for libraries when the `vala_gir:`
keyword argument is passed to library(). In that case, `install_dir:`
must be given a list with four elements, one for each output.
Includes tests for all these.
Closes https://github.com/mesonbuild/meson/issues/705
Closes https://github.com/mesonbuild/meson/issues/891
Closes https://github.com/mesonbuild/meson/issues/892
Closes https://github.com/mesonbuild/meson/issues/1178
Closes https://github.com/mesonbuild/meson/issues/1193
This avoids unnecessary rebuilds occuring when Meson regenerates the
build.ninja file. Previously, if the ordering of the commandline
arguments changed then Ninja would consider the outputs dirty and
rebuild them.
Jussi Pakkanen