When one CMakeLists.txt has several targets, add/delete-ing target affects emission of generator, even if a simple `add_custom_target(foo)` is added. This can be easily observable with Ninja generator. I guess other generators would be affected. This prevents CI. I am tracking difference of emitted build tree(s) between builds. I think, in general, it's not good thing to expose `unordered_map` to generated files. I could fix this, but I am afraid which would be suitable to CMake project. With s/`std::unordered_map`/`std::map`/ to `using cmTargetMap = std::unordered_map<std::string, cmTarget>;` in `cmMakefile.h`, emission will become stable. But this just stabilizes and would not be the right fix. I think it'd be best to emit targets with defined-order. `class cmMakefile` also has `OrderedTargets` but it is unavailable due to lack of a few targets, for example, `rebuild_cache` At first, let me show the right direction.