Configuring a build directory
Often you want to change the settings of your build after it has been
generated. For example you might want to change from a debug build
into a release build, set custom compiler flags, change the build
options provided in your meson.options file and so on.
The main tool for this is the meson configure command.
You invoke meson configure by giving it the location of your build
dir. If omitted, the current working directory is used instead. Here's
a sample output for a simple project.
Core properties
Source dir /home/jpakkane/clangdemo/2_address
Build dir /home/jpakkane/clangdemo/2_address/buildmeson
Core options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
auto_features auto [enabled, disabled, auto] Override value of all 'auto' features
backend ninja [ninja, vs, vs2010, vs2015, vs2017, vs2019, vs2022, xcode] Backend to use
buildtype release [plain, debug, debugoptimized, release, minsize, custom] Build type to use
debug false [true, false] Debug
default_library shared [shared, static, both] Default library type
install_umask 0022 [preserve, 0000-0777] Default umask to apply on permissions of installed files
layout mirror [mirror, flat] Build directory layout
optimization 3 [plain, 0, g, 1, 2, 3, s] Optimization level
prefer_static false [true, false] Whether to try static linking before shared linking
strip false [true, false] Strip targets on install
unity off [on, off, subprojects] Unity build
warning_level 1 [0, 1, 2, 3, everything] Compiler warning level to use
werror false [true, false] Treat warnings as errors
Backend options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
backend_max_links 0 >=0 Maximum number of linker processes to run or 0 for no limit
Base options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
b_asneeded true [true, false] Use -Wl,--as-needed when linking
b_colorout always [auto, always, never] Use colored output
b_coverage false [true, false] Enable coverage tracking.
b_lto false [true, false] Use link time optimization
b_lundef true [true, false] Use -Wl,--no-undefined when linking
b_ndebug false [true, false, if-release] Disable asserts
b_pch true [true, false] Use precompiled headers
b_pgo off [off, generate, use] Use profile guided optimization
b_sanitize none [none, address, thread, undefined, leak, memory, address,undefined] Code sanitizer to use
b_staticpic true [true, false] Build static libraries as position independent
Compiler options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
c_args [] Extra arguments passed to the C compiler
c_link_args [] Extra arguments passed to the C linker
c_std c99 [none, c89, c99, c11, c17, c18, c2x, c23, c2y, gnu89, gnu99, gnu11, gnu17, gnu18, gnu2x, gnu23, gnu2y] C language standard to use
cpp_args [] Extra arguments passed to the C++ compiler
cpp_debugstl false [true, false] STL debug mode
cpp_link_args [] Extra arguments passed to the C++ linker
cpp_std c++11 [none, c++98, c++03, c++11, c++14, c++17, c++1z, c++2a, c++20, gnu++03, gnu++11, gnu++14, gnu++17, gnu++1z, gnu++2a, gnu++20] C++ language standard to use
fortran_std [] [none, legacy, f95, f2003, f2008, f2018] language standard to use
Directories:
Option Current Value Description
------ ------------- -----------
bindir bin Executable directory
datadir share Data file directory
includedir include Header file directory
infodir share/info Info page directory
libdir lib/x86_64-linux-gnu Library directory
libexecdir libexec Library executable directory
localedir share/locale Locale data directory
localstatedir /var/local Localstate data directory
mandir share/man Manual page directory
prefix /usr/local Installation prefix
sbindir sbin System executable directory
sharedstatedir /var/local/lib Architecture-independent data directory
sysconfdir etc Sysconf data directory
Project options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
array_opt [one, two] [one, two, three] array_opt
combo_opt three [one, two, three] combo_opt
free_array_opt [one, two] free_array_opt
integer_opt 3 >=0, <=5 integer_opt
other_one false [true, false] other_one
some_feature enabled [enabled, disabled, auto] some_feature
someoption optval An option
Testing options:
Option Current Value Possible Values Description
------ ------------- --------------- -----------
errorlogs true [true, false] Whether to print the logs from failing tests
stdsplit true [true, false] Split stdout and stderr in test logs
These are all the options available for the current project arranged
into related groups. The first column in every field is the name of
the option. To set an option you use the -D option. For example,
changing the installation prefix from /usr/local to /tmp/testroot
you would issue the following command.
meson configure -Dprefix=/tmp/testroot
Then you would run your build command (usually meson compile), which
would cause Meson to detect that the build setup has changed and do
all the work required to bring your build tree up to date.
Since 0.50.0, it is also possible to get a list of all build options
by invoking meson configure with the
project source directory or the path to the root meson.build. In
this case, Meson will print the default values of all options similar
to the example output from above.
Per project subproject options rewrite (Since 1.8)
A common requirement when building large projects with many
subprojects is to build some (or all) subprojects with project options
that are different from the "main project". This has been sort of
possible in a limited way but is now natively supported. Per project
options can be added, changed and removed at runtime using the command
line, in other words, without editing existing meson.build files.
Starting with version 1.8 you can specify per-project option settings.
These can be specified for every top level (i.e. not project) options.
Suppose you have a project that has a single subproject called
numbercruncher that does heavy computation. During development you
want to build that subproject with optimizations enabled but your main
project without optimizations. This can be done by specifying a custom
value to the given subproject:
meson configure -Dnumbercruncher:optimization=3
Another case might be that you want to build with warnings as errors,
but some subproject does not support it. To configure werror per
subproject you can do:
meson configure -Dwerror=true -Dnaughty:werror=false
You can also specify a different value on the top level project. For example you could enable optimizations on all subprojects but not the top level project:
meson configure -Doptimization=2 -D:optimization=0
Note the colon after the second D.
Subproject specific values can be removed with -U
meson configure -Usubproject:optionnname
The results of the search are