speedup compilation with help of cmake 3.6 pch support #13581
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Since cmake 3.16 there is cross-platform support of precompiled
headers in cmake. So I add code to check version of cmake,
and if it is recent enough build system switches to cmake's pch
support.
I tested with such command:
touch qt/main.cpp && time ninja MAPS.ME
Before: ~ 35 seconds on my machine (average)
After: ~ 21 seconds (average)
What make this speedup possible:
happens only if something changed, while current PCH script cause
recompilation of headers every run of ninja. It takes ~ 4 seconds
and I include map/framework.hpp for "qt".