cmake --install and passing -j arg

Usage
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1

The following command works in 3.20:
cmake --install . -prefix <path> -- -j8
but in 3.30 it results in:
Unknown argument --

The documentation for the cmake --install command in both 3.20 and the latest 3.30 don’t say that -- is supported; though it is for the --build command. I assume it was either working as undocumented behavior in 3.20 or was being silently ignored.
This issue said that -j or --parallel option is available for --install which would be an alternative the for specific case of wanting to pass -j but that doesn’t seem to be true and there is nothing present in the documentation for this either.

Is there a way to run the equivalent of [make|ninja] install -j8 through the cmake --install command so it isn’t generator dependent? Whilst following the make convention of:

Running ‘make install’ with a different value of prefix from the one used to build the program should not recompile the program.

2

Seems like a command line parsing change. @robert.maynard?

3

I haven’t double checked but prior to 3.30 I think it was ignored completely.

To use parallel installs now, a project needs to opt-in via the INSTALL_PARALLEL global property. In CMake >= 3.31 that should enable using -j with cmake --install.

4

Thanks - I’ll give this a try and report back