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.
Special wrap modes:
nofallback: Don't download wraps for dependency() fallbacks
nodownload: Don't download wraps for all subproject() calls
Subprojects are used for two purposes:
1. To download and build dependencies by using .wrap files if they
are not provided by the system. This is usually expressed via
dependency(..., fallback: ...).
2. To download and build 'copylibs' which are meant to be used by
copying into your project. This is always done with an explicit
subproject() call.
--wrap-mode=nofallback will never do (1)
--wrap-mode=nodownload will do neither (1) nor (2)
If you are building from a release tarball, you should be able to
safely use 'nodownload' since upstream is expected to ship all
required sources with the tarball.
If you are building from a git repository, you will want to use
'nofallback' so that any 'copylib' wraps will be download as
subprojects.
Note that these options do not affect subprojects that are git
submodules since those are only usable in git repositories, and you
almost always want to download them.
For newer VS versions, we can simply rely on 'VisualStudioVersion' being
set in the environment.
For VS2010, we fall back to check 'VSINSTALLDIR' for the version string.
If the backend can not be auto detected, we raise an exception to make the
user choose an explicit backend.
We also print the detected backend to the meson log.
VS2017 requires the 'WindowsTargetPlatformVersion' property to be set.
We gather the version to use from the environment variable
'WindowsSDKVersion' that will be set by the VS developer command prompt.
With the exception of things like sysconfdir (/etc), every other
installation directory option must be inside the prefix.
Also move the prefix checks to coredata.py since prefix can also be set
from inside project() with default_options and via mesonconf. Earlier
you could set prefix to a relative path that way.
This also allows us to return consistent values for get_option('xxxdir')
regardless of whether relative paths are passed or absolute paths are
passed while setting options on the command-line, via mesonconf, or via
default_options in project(). Now the returned path will *always* be
relative to the prefix.
Includes a unit test for this, and a failing test.
Closes#1299
The script will manually delete all custom_target outputs that are
directories instead of files. This is needed because on platforms other
than Windows, Ninja only deletes directories while cleaning if they are
empty.
Closes#1220
I hit an issue when building gtk-doc documentation. The issue is
my fault, but the error output from Meson makes it look like an
internal error:
[0/1] 'Running external command libtracker-sparql-doc.'
Building documentation for libtracker-sparql
Traceback (most recent call last):
File "/home/sam/meson/meson.py", line 26, in <module>
sys.exit(main())
File "/home/sam/meson/meson.py", line 23, in main
return mesonmain.run(launcher, sys.argv[1:])
File "/home/sam/meson/mesonbuild/mesonmain.py", line 249, in run
sys.exit(run_script_command(args[1:]))
File "/home/sam/meson/mesonbuild/mesonmain.py", line 239, in run_script_command
return cmdfunc(cmdargs)
File "/home/sam/meson/mesonbuild/scripts/gtkdochelper.py", line 183, in run
options.ignore_headers.split('@@') if options.ignore_headers else [])
File "/home/sam/meson/mesonbuild/scripts/gtkdochelper.py", line 133, in build_gtkdoc
gtkdoc_run_check(mkhtml_cmd, os.path.join(abs_out, 'html'))
File "/home/sam/meson/mesonbuild/scripts/gtkdochelper.py", line 55, in gtkdoc_run_check
raise MesonException('\n'.join(err_msg))
mesonbuild.mesonlib.MesonException: 'gtkdoc-mkhtml' failed with status 6
warning: failed to load external entity "../overview.sgml"
../libtracker-sparql-docs.sgml:20: element include: XInclude error :
could not load ../overview.sgml, and no fallback was found
warning: failed to load external entity "../examples.sgml"
../libtracker-sparql-docs.sgml:41: element include: XInclude error :
could not load ../examples.sgml, and no fallback was found
FAILED: libtracker-sparql-doc
After this patch, the output is much clearer:
[0/1] 'Running external command libtracker-sparql-doc.'
Building documentation for libtracker-sparql
Error in gtkdoc helper script:
'gtkdoc-mkhtml' failed with status 6
warning: failed to load external entity "../overview.sgml"
../libtracker-sparql-docs.sgml:20: element include: XInclude error :
could not load ../overview.sgml, and no fallback was found
warning: failed to load external entity "../examples.sgml"
../libtracker-sparql-docs.sgml:41: element include: XInclude error :
could not load ../examples.sgml, and no fallback was found
Note the actual errors from xsltproc are swallowed by gtkdoc-mkhtml
1.25.1, they're only displayed in the example above because I made a
patch: <https://bugzilla.gnome.org/show_bug.cgi?id=774812>
In Fedora we don't care about prefix, we want to ensure that libdir
is /usr/lib64, localedir is /usr/share/locale, and cetera.
Additionally, we don't need to ensure that prefix is absolute as we
check it in main.
Fixes: cc19bf0f45 ("Move option validation in objects rather than doing it only in the conf script.")
Closes: https://github.com/mesonbuild/meson/issues/869
Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
When installing Meson, distutils may choose to put shim scripts in the
`PATH` that only set up the egg requirements before launching the real
`meson.py` contained in the egg.
This means that `__file__` points to the real `meson.py` file, but
launching it directly is doomed to fail as it's missing the metadata
contained in the shim to set up the path egg, resulting in errors when
trying to import the `mesonbuild` module.
A similar issue affects Meson when installed as a zipapp, with the
current code going great lengths to figure out how to relaunch itself.
Using `argv[0]` avoids these issues as it gives us the way the current
executable has been launched, so we are pretty much guaranteed that
using it will create another instance of the same executable. We only
need to resolve relative paths as the current working directory may
get changed before re-launching the script, and using `realpath()` for
that saves us the trouble of manually resolving links and getting caught
in endless loops.
This also mean that `meson_script_file` no longer necessarily point to a
absolute file, so rename it to `_launcher` which hopefully would be less
prone to inducing false assumptions.
After c01b183e5, the mtime of coredata.dat is always newer than all the
other build files, which made regen_checker think that they always had
to be regenerated. Now we set the mtime of the file to a value before
the build files are generated and that makes everything behave as it did
earlier.
Otherwise we'll mark the build directory as successfully configured even
if there's an error while doing the actual generation.
Reported on IRC by 'sdgsgad'
When a CustomTarget is run with a command that is an executable built
by the project which also has a DLL built in the same project as a
dependency, the EXE can't run on Windows because the DLL can't be found.
On UNIX-like systems, we set the RPATH using the linker so these
dependencies can be found, but on Windows the only way is to set the
PATH environment variable.
The same problem exists for tests, so we reuse that infrastructure by
creating a new meson_exe.py script that can be used as a wrapper to run
CustomTarget commands on Windows. This can later also be extended to add
support for setting an environment while calling the command needed to
generate a CustomTarget: https://github.com/mesonbuild/meson/issues/266
Jussi Pakkanen