cmake -E env much slower than plain env

Development
1

I was made aware of the following commit by the ccache maintainer. Apparently the raw env command is way faster than cmake -E env, which I guess is understandable. If you use cmake -E env a lot in a project, I guess maybe this could add up. I don’t know if we use it heavily internally within CMake for user projects, at least not enough to be noticeable outside use cases like those for launchers like ccache.

2

Can we get a profile of what takes so long? Is CMake still looking for CMAKE_ROOT and the like even when in -E mode?

3

You should be able to get them yourself easily I guess:

$ time env FOO=BAR true

real 0m0,001s
user 0m0,001s
sys 0m0,000s

$ time cmake -E env FOO=BAR true

real 0m0,006s
user 0m0,006s
sys 0m0,000s