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.
Sometimes you want to link to a C++ library that exports C API, which
means the linker must link in the C++ stdlib, and we must use a C++
compiler for linking. The same is also applicable for objc/objc++ etc,
so we can keep using clike_langs for the priority order.
Closes https://github.com/mesonbuild/meson/issues/1653
This detects and allows passing a generated file as a vs_module_def, it
also adds a testcase that tests using configure_file to generate the
.def file.
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
Previously, two functionally identical builds could produce different
build.ninja files. The ordering of the rules themselves doesn't affect
behaviour, but unnecessary changes in commandline arguments can cause
spurious rebuilds and if the ordering of the overall file is stable
than it's easy to use `diff` to compare different build.ninja files
and spot the differences in ordering that are triggering the unnecessary
rebuilds.
Now as long as you have a C compiler available in the project, it will
be used to compile assembly even if the target contains a C++ compiler
and even if the target contains only assembly and C++ sources.
Earlier, the order in which sources appeared in a target would decide
which compiler would be used.
However, if the project only provides a C++ compiler, that will be
used for compiling assembly sources.
If this breaks your use-case, please tell us.
Includes a test that ensures that all of the above is adhered to.
Use an ordered dict for the compiler dictionary and sort it according
to a priority order: fortran, c, c++, etc.
This also ensures that builds are reproducible because it would be
a toss-up whether a C or a C++ compiler would be used based on the
order in which compilers.items() would return items.
Closes https://github.com/mesonbuild/meson/issues/1370
We were adding them to the CompilerArgs instance in the order in which
they are specified, which is wrong because later dependencies would
override previous ones. Add them in the reverse order instead.
Closes https://github.com/mesonbuild/meson/issues/1495
This changes how generated files are added to the VS project.
Previously, they were all added as a single CustomBuildStep with all
generator commands, inputs and outputs merged together.
Now, each input file is added separately to the project and is given a
CustomBuild command. This adds all generator input files to the files list
in the VS gui and allows to run only some of the generator commands if
only some of the input files have changed.
We check for the existence of PDB files in the install script, so we
don't need to do all this mucking about here. That's more robust too
because we don't need to parse build arguments in buildtype=plain
and decide if the PDB file would be generated.
This means replacing @PLAINNAME@ and @BASENAME@ in the outputs. This is
the same feature as generator().
This is only allowed when there is only one input file for obvious
reasons + failing test for this.
Factor it out into a function in mesonlib.py. This will allow us to
reuse it for generators and for configure_file(). The latter doesn't
implement this at all right now.
Also includes unit tests.
Without this, files() in the arguments give an error because it's a list
of mesonlib.File objects:
Array as argument 1 contains a non-string.
It also breaks in nested lists. Includes a test for this.
At the same time, also fix the order in which compile arguments are
added. Detailed comments have been added concerning the priority and
order of the arguments.
Also adds a unit test and an integration test for the same.
With the 'install_mode' kwarg, you can now specify the file and
directory permissions and the owner and the group to be used while
installing. You can pass either:
* A single string specifying just the permissions
* A list of strings with:
- The first argument a string of permissions
- The second argument a string specifying the owner or
an int specifying the uid
- The third argument a string specifying the group or
an int specifying the gid
Specifying `false` as any of the arguments skips setting that one.
The format of the permissions kwarg is the same as the symbolic
notation used by ls -l with the first character that specifies 'd',
'-', 'c', etc for the file type omitted since that is always obvious
from the context.
Includes unit tests for the same. Sadly these only run on Linux right
now, but we want them to run on all platforms. We do set the mode in the
integration tests for all platforms but we don't check if they were
actually set correctly.
Set the rules for the symlinking on the target itself, and then reuse
that information while generating aliases during the build, and then
pass it to the install script too.
Jussi Pakkanen
Dylan Baker
Nirbheek Chauhan
Jon Turney
Sam Thursfield
Patrick Griffis
Nicolas Schneider
Mike Sinkovsky
Elliott Sales de Andrade
Igor Gnatenko