Hi IOhannes,On Mon, 08 Sep 2025 14:57:28 +0200 =?utf-8?q?IOhannes_m_zm=C3=B6lnig_=28Debian/GNU=29?= <[email protected]> wrote:
this works nicely with CMake-3.x.however, for reasons unknown to me, the very same code with CMake-4.x installs the files to /usr/lib/$(DEB_HOST_MULTIARCH)
I looked into it, and it turns out CMake 4 gained some code in GNUInstallDirs.cmake to automatically update the CMAKE_INSTALL_<dir> variables if the CMAKE_INSTALL_PREFIX is changed after the initial configuration step, to deal with the special cases for the "/" and "/usr" prefixes (/lib/MULTIARCH, /etc, ...).
The code tries to be smart and not update the variables if they have a non-default value. However, "lib" happens to be the initial default for LIBDIR, so the CMake will happily (and wrongly) update your manually set variable when the CMAKE_INSTALL_PREFIX is initialized with "/usr".
I will file a bug with upstream. In the meantime, I found that using an equivalent but not string-equal value works around the issue. For example, both -DCMAKE_INSTALL_LIBDIR=./lib or -DMCAKE_INSTALL_LIBDIR=lib/ seem to work.
Cheers Timo -- ⢀⣴⠾⠻⢶⣦⠀ ╭────────────────────────────────────────────────────╮ ⣾⠁⢠⠒⠀⣿⡁ │ Timo Röhling │ ⢿⡄⠘⠷⠚⠋⠀ │ 9B03 EBB9 8300 DF97 C2B1 23BF CC8C 6BDD 1403 F4CA │ ⠈⠳⣄⠀⠀⠀⠀ ╰────────────────────────────────────────────────────╯
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