qiBuild tips and tricks

Here is a few collections of tips and tricks when using the qibuild framework

See also

• CMake coding guide
• CMake common mistakes

Use qibuild help

The builtin documentation is directly generated from the source code, so it will always be accurate.

Trust it and use it!

You can use

qibuild help

To see a short description of all qibuild actions, and also

$ qibuild help <action>

To see the full help of the given action

Subdirectories order

First of, a reminder: you should never use subdirs, but use add_subdirectory instead

subdirs is deprecated, and, worse, the parsing order when using subdirs is not defined!

Let’s assume you have a foobar project, with two libraries, foo and bar, with bar depending on foo

You could end up write something like

# foobar/ CMakeLists.txt
project(foobar)
add_subdirectory(bar)
add_subdirectory(foo)

# foobar/bar/CMakeLists.txt
qi_create_lib(bar bar.cpp)
qi_use_lib(bar foo)

# foobar/foo/CMakeLists.txt
qi_create_lib(foo bar.cpp)
qi_stage_lib(foo)

But then you will have this strange message:

$ qibuild configure foobar

Could not find module FindFoo.cmake or a configuration
file for package FOO.

Adjust CMAKE_MODULE_PATH to find FindFOO.cmake or set
FOO_DIR to the directory containing a CMake configuration
file for FOO.  The file will have one of the following
names:

FooConfig.cmake
foo-config.cmake

This strange message will magically go away the next time you run cmake or qibuild configure ...

Why?

Because CMake only parses the CMakeLists only once.

So by the time it gets through bar/CMakeLists.txt, it has not parsed foo/CMakeLists.txt yet, so the foo library has not been staged yet.

But it does not stop the processing, and stages the foo library anyway ...

So the basic rule should be:

Always clean up build/sdk when changing CMake dependencies

The fix is easy: make sure you stage the foo library before using it:

# foobar/ CMakeLists.txt
project(foobar)
add_subdirectory(foo)
add_subdirectory(bar)

Compile warnings

By default, qibuild will not change your compile flags at all.

If you work in a cross-platform environment, it is advised you use qi_sanitize_compile_flags

find_package(qibuild)
qi_sanitize_compile_flags()

This will triggers compile warnings for all platforms (cl.exe and gcc.exe)

You can then use

$ qibuild configure --werror

To make sure compile warnings will be treated as errors for any following build of the same project.