Remove the base.h include from source code.

[Shylock-Hg]

Is your feature request related to a problem? Please describe.
It's not a precompiled header again, and it include many headers which don't need in many source file. I think this will slow the compiling, so we'd better remove this include.

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[JingLiofLiJing]

As far as i know, if a source file needs a subset of header files listed in pch.h, when pch.gch is found, it will be used direclty instead of precompile those original header files again, which should speed up the building speed of this translation unit. Maybe the main trouble is not the speed , namespace pollution or symbolic conflicts may happen when including many unused header files including third-party header files in pch-header.h? @Shylock-Hg

[Shylock-Hg]

As far as i know, if a source file needs a subset of header files listed in pch.h, when pch.gch is found, it will be used direclty instead of precompile those original header files again, which should speed up the building speed of this translation unit. Maybe the main trouble is not the speed , namespace pollution or symbolic conflicts may happen when including many unused header files including third-party header files in pch-header.h? @Shylock-Hg

We don't enable the precompiled header already.

[JingLiofLiJing]

As far as i know, if a source file needs a subset of header files listed in pch.h, when pch.gch is found, it will be used direclty instead of precompile those original header files again, which should speed up the building speed of this translation unit. Maybe the main trouble is not the speed , namespace pollution or symbolic conflicts may happen when including many unused header files including third-party header files in pch-header.h? @Shylock-Hg

We don't enable the precompiled header already.

Sorry for my statement. Recently, i have implememted the cmake-pch module for my personal project and it successfully speeds up the whole compilation stage. But according to this issue, i have a little concern about the disadvantages of pch on large projects like nebula，and unsure wheteher to keep this module or not. Is there some engineering guidelines and experience in this area? @Shylock-Hg

[Shylock-Hg]

As far as i know, if a source file needs a subset of header files listed in pch.h, when pch.gch is found, it will be used direclty instead of precompile those original header files again, which should speed up the building speed of this translation unit. Maybe the main trouble is not the speed , namespace pollution or symbolic conflicts may happen when including many unused header files including third-party header files in pch-header.h? @Shylock-Hg

We don't enable the precompiled header already.

Sorry for my statement. Recently, i have implememted the cmake-pch module for my personal project and it successfully speeds up the whole compilation stage. But according to this issue, i have a little concern about the disadvantages of pch on large projects like nebula，and unsure wheteher to keep this module or not. Is there some engineering guidelines and experience in this area? @Shylock-Hg

See the detail in #2070