How can I skip CMake compiler identification? - c++

Question

I'm running some tests on my software environment. This does hundreds of calls to CMake to configure many projects, always using the same compiler.
For every call to CMake, it checks the compiler:
-- Selecting Windows SDK version to target Windows 10.0.16299.
-- The C compiler identification is MSVC 19.0.24215.1
-- The CXX compiler identification is MSVC 19.0.24215.1
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio 14.0/VC/bin/x86_amd64/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
This takes a while and is useless to be done many time as it will always end with the same result on the machine running those tests.
Is there no way to "cache" compiler check result and have it be done once only?

Answer 1

fdan recommended (in a comment) to add a top level CMake projects adding all sub-projects using add_subdirectory. I did not try that but it looks like something that would wok.
In the mean time, I found an alternative is to:
Create an empty CMakeLists.txt file
Run CMake on it, it checks the compiler. This produces some files including a CMakeCache.txt and a CMakeFiles folder.
For every next project you will run CMake on
Copy the output of the first run you did with the empty project (including CMakeCache.txt and a CMakeFiles folder)
Modify CMakeCache.txt content to reference the new project folder instead of the old one (else Cmake will report CMake Error: The current CMakeCache.txt directory ... is different than the directory ... where CMakeCache.txt was created).
Then compiler check will not be processed when you'll configure the next project