How to match major version only in cmake - cmake

Question

I am trying to build a project that requires LLVM 11 as a dependency. They bundle a copy of LLVM 11.0.1. I want to build it against the system version, which is LLVM 11.1.0. In the cmake build files, they have:
find_package(LLVM 11.0 CONFIG)
If you try to use the system LLVM, you get the following error:
CMake Warning at 3rdparty/llvm.cmake:42 (find_package):
Could not find a configuration file for package "LLVM" that is compatible
with requested version "11.0".
The following configuration files were considered but not accepted:
/usr/lib/llvm/11/lib64/cmake/llvm/LLVMConfig.cmake, version: 11.1.0
/usr/lib/llvm/11/lib/cmake/llvm/LLVMConfig.cmake, version: 11.1.0
Call Stack (most recent call first):
3rdparty/CMakeLists.txt:436 (include)
I thought that changing the line to this would fix it:
find_package(LLVM 11 CONFIG)
but it doesn't, and I get the exact same error:
CMake Warning at 3rdparty/llvm.cmake:42 (find_package):
Could not find a configuration file for package "LLVM" that is compatible
with requested version "11".
The following configuration files were considered but not accepted:
/usr/lib/llvm/11/lib64/cmake/llvm/LLVMConfig.cmake, version: 11.1.0
/usr/lib/llvm/11/lib/cmake/llvm/LLVMConfig.cmake, version: 11.1.0
Call Stack (most recent call first):
3rdparty/CMakeLists.txt:436 (include)
What am I missing? Here is a full link to the code: https://github.com/RPCS3/rpcs3/blob/master/3rdparty/llvm.cmake

Answer 1

Whether a version is deemed compatible to the requested version is specified by the package you're trying to find. I haven't looked at the LLVM config, but I suspect it specifies that only the exact version is compatible instead of all versions with the same major version.
If you're running CMake 3.19 or later you can pass a version range to find_package, so you could try find_package(LLVM 11...<12 CONFIG) instead.