Passing build variables using command line

Usage
#1

I’d like to override the cmake cached variable using the command line. But if a variable is repeatedly provided, does the last value take effect?

# what is the value of FOO?
> cmake -DFOO=123 -DFOO=321

Update:
Test result shows that the last value takes effect. However, I couldn’t find any documentation describing such behavior. Is this behavior consistent across different OS? Should I write script based on this assumption?

#2

This is easy to test:

message("${foo}")

$ cmake -Dfoo=first -Dfoo=second -P foo.cmake
second
#3

Yes, the last takes place from my test as well. However, this behavior is not documented anywhere. I’m wondering if I can write script based on this assumption.

#4

Given CMake’s backwards compatibility guarantees, it is likely something we’d need to guarantee in the future. Please open an issue for us to make sure it is in the documentation.

1 Like
#5

Thanks! The issue has been created.

Documentation: override the same build variable multiple times from command line (#21707) · Issues · CMake / CMake · GitLab (kitware.com)