1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
# How do I do X in Meson?
This page lists code snippets for common tasks. These are written mostly using the C compiler, but the same approach should work on almost all other compilers.
# Set compiler
When first running Meson, set it in an environment variable.
```console
$ CC=mycc meson <options>
```
# Set default C/C++ language version
```meson
project('myproj', 'c', 'cpp',
default_options : ['c_std=c11', 'cpp_std=c++11'])
```
# Enable threads
Lots of people seem to do this manually with `find_library('phtread')` or something similar. Do not do that. It is not portable. Instead do this.
```meson
thread_dep = dependency('threads')
executable(..., dependencies : thread_dep)
```
# Set extra compiler and linker flags from the outside (when e.g. building distro packages)
The behaviour is the same as with other build systems, with environment variables during first invocation.
```console
$ CFLAGS=-fsomething LDFLAGS=-Wl,--linker-flag meson <options>
```
# Use an argument only with a specific compiler
First check which arguments to use.
```meson
if meson.get_compiler('c').get_id() == 'clang'
extra_args = ['-fclang-flag']
else
extra_args = []
endif
```
Then use it in a target.
```meson
executable(..., c_args : extra_args)
```
If you want to use the arguments on all targets, then do this.
```meson
if meson.get_compiler('c').get_id() == 'clang'
add_global_arguments('-fclang-flag', language : 'c')
endif
```
# Set a command's output to configuration
```meson
txt = run_command('script', 'argument').stdout().strip()
cdata = configuration_data()
cdata.set('SOMETHING', txt)
configure_file(...)
```
# Generate a runnable script with `configure_file`
`configure_file` preserves metadata so if your template file has execute permissions, the generated file will have them too.
## Producing a coverage report
First initialise the build directory with this command.
```console
$ meson <other flags> -Db_coverage=true
```
Then issue the following commands.
```console
$ ninja
$ ninja test
$ ninja coverage-html (or coverage-xml)
```
The coverage report can be found in the meson-logs subdirectory.
## Add some optimization to debug builds ##
By default the debug build does not use any optimizations. This is the desired approach most of the time. However some projects benefit from having some minor optimizations enabled. Gcc even has a specific compiler flag `-Og` for this. To enable its use, just issue the following command.
```console
$ mesonconf -Dc_args=-Og
```
This causes all subsequent builds to use this command line argument.
## Use address sanitizer
Clang comes with a selection of analysis tools such as the [address sanitizer](http://clang.llvm.org/docs/AddressSanitizer.html). Meson has native support for these with the `b_sanitize` option.
```console
$ meson <other options> -Db_sanitize=address
```
After this you just compile your code and run the test suite. Address sanitizer will abort executables which have bugs so they show up as test failures.
## Use Clang static analyzer
Install scan-build and configure your project. Then do this:
```console
$ ninja scan-build
```
## Use profile guided optimization
Using profile guided optimization with GCC is a two phase operation. First we set up the project with profile measurements enabled and compile it.
```console
$ meson <Meson options, such as --buildtype=debugoptimized> -Db_pgo=generate
$ ninja -C builddir
```
Then we need to run the program with some representative input. This step depends on your project.
Once that is done we change the compiler flags to use the generated information and rebuild.
```console
$ mesonconf -Db_pgo=use
$ ninja
```
After these steps the resulting binary is fully optimized.
## Add math library (`-lm`) portably
Some platforms (e.g. Linux) have a standalone math library. Other platforms (pretty much everyone else) do not. How to specify that `m` is used only when needed?
```meson
cc = meson.get_compiler('c')
m_dep = cc.find_library('m', required : false)
executable(..., dependencies : m_dep)
```
## Install an executable to `libexecdir`
```meson
executable(..., install : true, install_dir : get_option('libexecdir'))
```
----
[Wiki home](index.md)
|
