[CMake] Complete rebuild after svn update

[william.crocker at analog.com]

Have you checked the Makefiles which CMake creates
to see if there are any surprising dependencies
which could be causing the large extent of the recompile.

Alex Brooks wrote:
> Thanks for the quick responses.
> Comments inline:
> 
> Eric:
> 
>> May be svn is the culprit.
>>
>> Did you have a look at the timestamp of the file/directory enclosing
>> (and up) the
>> changed CMakeLists.txt after the svn update?
>>
>> May be a single change inside a directory change the timestamp
>> of a set of file?
> 
> When an svn update pulls in a change to a CMakeLists.txt file, the following 
> timestamps are updated:
>  1. the timestamp of the CMakeLists.txt file itself, and
>  2. the timestamp of the directory.
> 
> If I manually do a 'touch CMakeLists.txt', it changes the timestamp of the file 
> itself but not the directory.
> 
> I don't know why this might cause a complete rebuild.
> If I manually do 'touch .; touch CMakeLists.txt; make' somewhere in the source 
> tree, it doesn't force a rebuild.
>  
>> Another option may be that this particular CMakeLists.txt is generating
>> (using configure_file) some file that is [indirectly] included by many
>> other?
> 
> I've looked for this kind of thing.  Files which do not depend on any 
> dynamically-generated files also get rebuilt.
>  
>> May be you can have look at the dependencies in
>> CMakeFiles/Makefile.cmake
> 
> I don't have this file, but I have CMakeFiles/Xxx.dir/depend.cmake.
> Here's a sample:
> 
> # CMAKE generated file: DO NOT EDIT!
> # Generated by "Unix Makefiles" Generator, CMake Version 2.8
> 
> orca/src/hydrolibs/hydrodll/CMakeFiles/HydroDll.dir/dll.cpp.o: 
> orca/src/hydrolibs/hydrodll/dll.cpp
> orca/src/hydrolibs/hydrodll/CMakeFiles/HydroDll.dir/dll.cpp.o: 
> orca/src/hydrolibs/hydrodll/dll.h
> orca/src/hydrolibs/hydrodll/CMakeFiles/HydroDll.dir/dll.cpp.o: 
> orca/src/hydrolibs/hydrodll/exceptions.h
> 
> In this case, when a rebuild is forced I always see dll.cpp.o get rebuilt 
> (despite no changes to dll.h/dll.cpp/exceptions.h)
> All of these files are written by hand, not are generated using configure_file.
> 
> 
> Marcel:
> 
>> Or do you use keyword expansion in your CMakeLists.txt file. Keywords,
>> like $Id$, $Author$, etc. are a relict from CVS, but still supported by
>> Subversion, though you have to explicitly activate it using properties.
> 
> No, I don't use anything like this.  If I diff the files mentioned in e.g. the 
> "hydrodll" directory above, there are no changes (and the timestamps haven't 
> moved).  But an svn update to an unrelated directory causes a rebuild.
> 
> 
> Any other ideas?
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