Are the commands "cmake -build . --target package" and "cpack ." equivalent?

Usage
1

Are the commands “cmake -build . --target package” and “cpack .” fully equivalent?

If yes, why would one ever use the former?

(One possible reason I know: Under Windows, cpack is ambiguous, as Chocolatey has an obsolete cpack.exe.)

2

They are more or less equivalent, yes. The package target exists so you can run make package or ninja package. Running cmake --build . --target package does seem a little silly to me… if you’re using the CMake command line tools anyway, you might as well use cpack at that point.

3

The cmake --build . --target package command is logically equivalent to running cpack, but there are important differences:

  • I think cmake --build . --target package will also build the all target first, whereas running cpack directly won’t. Perhaps @kyle.edwards can confirm this?
  • Running cpack directly supports many options that allow you to control the behavior (e.g. specifying which package generators to use), whereas cmake --build . --target package can only support the defaults set by the project.
  • If you want to create a multi-config package, you can do that by invoking cpack -C .... There is no equivalent for cmake --build . --target package, which can only build/package a single configuration.
4

Yes, package is a build-in target in CMake with dependeny to ALL.

I mentioned that here yesterday:

5

cpack . will also run the install target on your project, so it also basically has a dependency on ALL as well.

6

Turns out that’s not accurate. cpack will run the cmake_install.cmake script, it won’t build the install target. I did some local testing to confirm that my original comment was correct: cmake --build . --target package will also build the all target first, whereas running cpack directly won’t.

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7

Hmm, guess I was mistaken then. There was definitely some reason I had split the packaging steps out from the main build in our superbuilds, but maybe that was due to looking to support different packaging layouts with a single build tree (where install dirs depend on the packaging format).