# qiBuild tips and tricks ¶

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

## 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)



## 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.