[SOLVED] cmake building in source directory, not PWD

Issue

The question Debug vs Release in CMake indicates that

cd ~/codebase
mkdir Release
cd Release
cmake -DCMAKE_BUILD_TYPE=Release ..
make

Will create the Makefile in release, and build the binary there. The intermediate .o files will be in a subdirectory of this.

However, when I do this with my project, CMake ignores the PWD that it is started from. The final target is always the directory ~/codebase/ which contains CMakeList.txt. In the cmake-gui tool, I specified the source and build directories to be the same directory, the FQN to codebase

I'm new to CMake, and don't know how to get this to work as I expect. What should I modify to get this work as expected?

Solution

If you are using a single configuration generator (Ninja/Unix-Makefiles)

Then you need a build folder for each configuration.

Like this:

# Configure the build
cmake -S . -B build/Debug -D CMAKE_BUILD_TYPE=Release

# Actually build the binaries
cmake --build build/Debug

For multi-configuration generators it's slightly different (Ninja Multi-Config, Visual Studio)

# Configure the build
cmake -S . -B build

# Actually build the binaries
cmake --build build --config Debug

If you are wondering why this is necessary it's because cmake isn't a build system. It's a meta-build system (IE a build system that creates build systems). This is basically the result of handling build systems that support multiple-configurations in 1 build. If you'd like a deeper understanding I'd suggest reading a bit about cmake in Craig Scott's book "Professional CMake: A Practical Guide

Note: My examples use newer cmake cli practices.

EDIT: That question you linked to has dangerously out of date answers...

Answered By - user12322620