Custom values in Qt Creator (CMake) build settings

I want to achieve the equivalent of C++ #define foo "bar" but I don't want the value "bar" to be part of my code repository, and the value will depend on whether the build is Debug or Release.

How can I do this?

NB: I like the idea of using the following in CMakeLists.txt add_compile_definitions(foo="bar") but I don't know how to supply "bar" from the Qt Creator build settings.

Presumably I'd add a Key/Value pair but what would I put?

You need a 2 step process:

1. Add a Qt Creator build setting to create a CMake cache variable.
2. In CMakeLists.txt use the cache variable within a command.

For your example:

1. In Qt Creator build settings,

• either click Add > String setting Key to MYPROJECT_FOO and Value to bar
• or click Batch Edit... and add -DMYPROJECT_FOO:STRING=bar

2. In CMakeLists,

target_compile_definitions(mytarget PUBLIC foo="${MYPROJECT_FOO}")

(As advised by Guillaume Racicot it's better to apply the definition to a single target, as opposed to the entire project, which would be add_compile_definitions(foo="${MYPROJECT_FOO}").)

See also Qt Creator documentation CMake Build Configuration: Modifying Variable Values.

Thanks to Guillaume Racicot for deeper explanation of how CMake cache variables can be used.