[CMake] How to build only when file contents are actually changed?

[Eric Noulard]

2012/8/14 Peng Yu <pengyu.ut at gmail.com>:
>>> o Makepp will not recompile if only comments or whitespace in
>>>   C/C++ sources have changed.  This is especially important for header
>>>   files which are automatically generated by other programs and are
>>>   included in many modules.  Even if the date has changed because the
>>>   file was remade, makepp won't recompile if the file hasn't changed.
>>>
>>
>> That's plenty dangerous! Only a full C/C++ compiler can decide whether
>> something is a comment or not (as this requires full parsing
>> capabilities) and further it might interfere with compiler bugs; I
>> remember having the problem that with -O3 and old version of the Apple
>> GCC produced code that segfaulted depending on whether a certain comment
>> line was present or not!
>
> This depends on how many different things in C++ are used. With some
> restrictions, the drawbacks of this approach can be circumvented. To
> work with some legacy code which include things that may cause
> failure, makepp may not be the appropriate tool. For a project
> starting from scratch (so these intruding things can be forbidden),
> makepp can be a very good tool as it results in much less makefile to
> write compared with cmake.