Sorry, but comparing lines at that state is just bullshit.
I totally disagree, proportions will be same in any case.
Most of the comments of converted tests are missing.
Add 100-500 lines? ok.
You detect like a third of the things that the old configure detected.
I tried to use CMake way when it exists but for some other things, I porting checking from old autoconf system.
The thread safety check definitely aren't comparable. The int128 type checks aren't comparable.
The atomics check don't guard against compilers that allow to reference undefined functions at compile time.
I am not sure about "comparable", but anyway you can make PR with a fix or at least make an issue in my tracker and I fix it.
No LLVM detection.
Sure! Because my code base still on postgres 10. After all words about new build system and cmake here, I have no plan to support not released versions. I am not a masochist...