Building Out-of-Tree

While it is common to build a project in-place, many projects will also support building out-of-tree. That is, generated files such as object files and executables are created in a tree outside the project source code. This approach can be useful when building multiple versions of a project with different options.

Building out-of-tree simply involves invoking configure from an empty directory other than the top of the source tree.

For example, to create a debug build in the build-debug directory:

$ mkdir build-debug
$ cd build-debug
$ ../configure CFLAGS="-g -O0"
$ make
$ cd ..

And to create a release build in the build-release directory:

$ mkdir build-release
$ cd build-release
$ ../configure CFLAGS="-O2"
$ make
$ cd ..

Notes:

• The project must be enabled for out-of-tree builds, typically with the user of VPATH if using make
• The source tree should be clean (i.e. no build should be done in the original source directory), otherwise it will confuse make