After a lot of discussion in this diff the consensus was that it is really hard to guess the users intention with their LLVM build. Instead of trying to guess if Debug or Release is the correct default option we opted for just not specifying CMAKE_BUILD_TYPE a error.
Discussion on discourse here:
https://discourse.llvm.org/t/rfc-select-a-better-linker-by-default-or-warn-about-using-bfd
Reviewed By: hans, mehdi_amini, aaron.ballman, jhenderson, MaskRay, awarzynski
Differential Revision: https://reviews.llvm.org/D124153
This patch updates the cmake options suggested when cross compiling. This should fix [#52819](https://github.com/llvm/llvm-project/issues/52819).
Brad King (Member of CMake) says:
The linked [CMAKE_CROSSCOMPILING](https://cmake.org/cmake/help/v3.22/variable/CMAKE_CROSSCOMPILING.html) documentation says:
This variable will be set to true by CMake if the `CMAKE_SYSTEM_NAME` variable has been set manually (i.e. in a toolchain file or as a cache entry from the cmake command line).
It is not meant to be set by project code or toolchain files. It is always set automatically. Don't put `set(CMAKE_CROSSCOMPILING ON)` anywhere in your code.
`CMAKE_CROSSCOMPILING` indicates only whether `CMAKE_SYSTEM_NAME` was set by the user/project/toolchain-file instead of by CMake.
In LLVM project, `CMAKE_CROSSCOMPILING` is used to determine whether to execute some tests on the host machine.
LLVM needs to use another method for that. `CMAKE_CROSSCOMPILING` is not a reliable indicator of whether produced binaries will run on the host, and does not claim so in its documentation. If one sets `CMAKE_SYSTEM_NAME` to Linux in a toolchain file, and builds on a Linux host, that doesn't mean the target architecture or minimum glibc version is the same.
Reviewed By: rengolin
Differential Revision: https://reviews.llvm.org/D119804
Seems like my sphynx version is different than the one in the bot, as it
accepted everything locally. I think this is the right fix...
llvm-svn: 269062
HowToCrossCompile was outdated and generating too much traffic on the mailing
list with similar queries. This change helps offset most of the problems that
were reported recently including:
* Removing the -ccc-gcc-name, adding --sysroot
* Making references to Debian's multiarch for target libraries
* Expanding -DCMAKE_CXX_FLAGS for both GCC and Clang
* Some formatting and clarifications in the text
llvm-svn: 269054
Tobias Hieta