Bug#1110961: debhelper: Consider setting CMAKE_SYSTEM_PROCESSOR even when not cross-compiling

[Niels Thykier]

Control: tags -1 moreinfo help

Colin Watson:

Package: debhelper
Version: 13.24.2
Severity: wishlist

In https://bugs.debian.org/1103589, I noticed that the upstream
CMakeLists.txt was misdetecting the intended host architecture as arm64
due to `CMAKE_SYSTEM_PROCESSOR MATCHES
"^(aarch64|arm64|armv[89].?|ARM64)$"`.  debhelper's cmake buildsystem
sets CMAKE_SYSTEM_PROCESSOR when cross-compiling to armhf, but when not
cross-compiling it allows cmake to use its default.  According to
https://cmake.org/cmake/help/latest/variable/CMAKE_SYSTEM_PROCESSOR.html
that falls back to CMAKE_HOST_SYSTEM_PROCESSOR, which is just the output
of `uname -m` when building on Linux.

For CMAKE_SYSTEM_NAME it doesn't matter since the autodetection is
pretty likely to be correct, but it's fairly well-known that `uname -m`
is an inappropriate thing to use when configuring package builds.
Should debhelper perhaps pass -DCMAKE_SYSTEM_PROCESSOR also in the
non-cross-compiling case?

Thanks,

Hi Colin,

Thanks for the suggestion and for the follow up clarifying that more might be needed. Sadly, I am not an expert on this matter, so all I can do for now is tag the bug `moreinfo help`. I have CC'ed the CMake team in case they can help with this. For the CMake team, there is more context in https://bugs.debian.org/1110961#10 not quoted here.

Best regards,
Niels

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