[CMake] CMake rebuilds every time

[Arindam Mukherjee]

On Thu, Oct 25, 2012 at 6:02 PM, Arindam Mukherjee
<arindam.mukerjee at gmail.com> wrote:
> On Mon, Oct 22, 2012 at 5:55 PM, David Cole <david.cole at kitware.com> wrote:
>> On Mon, Oct 22, 2012 at 6:38 AM, Arindam Mukherjee
>> <arindam.mukerjee at gmail.com> wrote:
>>> On Mon, Oct 22, 2012 at 4:06 PM, Arindam Mukherjee
>>> <arindam.mukerjee at gmail.com> wrote:
>>>> I am sorry I missed your response. Here are the details:
>>>>
>>>> 1. I have a shell / batch script which does two things:
>>>>     a. cd build_dir && cmake $SRC_PATH
>>>>     b. make   # On Unix
>>>>
>>>>     On Windows, for step b., we run
>>>>     devenv proj.sln /Build "Release|x86" /out <logfile_path>
>>>>
>>>> Here is the top level CMakeLists.txt:
>>>> http://pastebin.com/QWG4wSuf
>>>>
>>>> Here is a CMakeLists.txt in one of the subdirs:
>>>> http://pastebin.com/QYGCpH7k
>>>>
>>>> These are fairly representative of how the CMakeLists.txt are.
>>>
>>> I should have added - we have source files with extension ".C" (i.e.
>>> .C in caps) and these are meant to be C++ sources.
>>>
>>>>
>>>> Regards,
>>>> Arindam
>>>>
>>>> On Tue, Oct 16, 2012 at 9:04 PM, David Cole <david.cole at kitware.com> wrote:
>>>>> What does your CMakeLists look like?
>>>>>
>>>>> Only the necessary rebuild steps should be taken on an incremental build.
>>>>>
>>>>> How do you invoke a rebuild? (Just typing 'make' or some other mechanism?)
>>>>>
>>>>>
>>>>> On Mon, Oct 15, 2012 at 6:22 AM, Arindam Mukherjee
>>>>> <arindam.mukerjee at gmail.com> wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I have a cross-platform build setup using cmake 2.8.9 which builds on
>>>>>> 5 different OSs. However it rebuilds every time even when neither the
>>>>>> Makefile timestamps nor the source file timastamps had changed.
>>>>>> Examining the generated Makefiles I can see that all .o, .i and .s
>>>>>> targets have been marked .PHONY. Don't know if this is the reason for
>>>>>> it. How to fix this to not rebuild every time but do incremental
>>>>>> builds?
>>>>>>
>>>>>> Thanks,
>>>>>> Arindam
>>>>>> --
>>>>>>
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>>
>> The *.C files will only be seen as "C" files on Windows because the
>> file system is case insensitive, so there is no difference between "c"
>> and "C"... Use ".cpp" or ".cxx" to name C++ source files.
>
> I have attached a .tgz archive with which the issue can be reproduced.
> Here are the instructions to run the
> build on a Linux system with gcc and gmake (I have tested it on RHEL
> 5.0 and Lubuntu 12.04):
>
> $ mkdir -p cmake_dbg && cmake_dbg
> $ tar xfz <path_to_archive>/cmake_dbg.tgz
> $ . ./bldenv `pwd`
> $ cd my_proj
> $ ./src/mk/build
>
> The sources get rebuilt every time I run ./src/mk/build. Tested with
> cmake 2.8.9 and 2.8.7.
>
> I added the following line to the top-level CMakeLists.txt file:
>
> set (CMAKE_SKIP_RULE_DEPENDENCY TRUE)
>
> and I can now get incremental builds
> (source:http://www.vtk.org/Wiki/CMake_Useful_Variables#Various_Options).
> However I was hoping I didn't have to do that because I am not really
> changing any options.
>

Did someone get a chance to look at this one.

Arindam