buildsystem: fix cyclic dependency on unnecessary timefile #1084
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This caused rebuilds because the generated files depend on the first file (see cmake sources, e.g. https://github.com/Kitware/CMake/blob/b4ccb6cd32029efa802dfdfa889c75bc16f65cf1/Source/cmMakefileTargetGenerator.cxx#L974-L1006). The first file (the timefile) is touched after the files were generated. The generated files are then older than the timefile, and are touched, causing rebuils for any (non-generated) source file depending on them.
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zuntrax
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Jan 27, 2019
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The timefile is problematic: cmake says in the implementation of
cmMakefileTargetGenerator::WriteMakeRule:-> the first output was the timefile, the extra ones are the generated sources.
But the timefile is touched after the sources were generated. The generated sources depend on the (now newer) timefile, so they need to be rebuilt, i.e. touched. Then the generated ones are newer than the dependent C++ files, causing funny unnecessary rebuilds.
Finally fixes #1075.