-----Original Message-----
From: Tobias Hunger <[email protected]>
Date: Wednesday, September 27, 2017 at 6:11 PM
To: Michael Jackson <[email protected]>
Cc: qt-creator <[email protected]>
Subject: Re: [Qt-creator] QtCreator 4.3/4.4 + CMake likes to "rebuild" my
project, a lot.
Hi Michael,
On Wed, Sep 27, 2017 at 3:58 PM, Michael Jackson
<[email protected]> wrote:
> I have seen this problem more than a few times and with a 45 minute build
time for our project it is starting to get in the way. Our project is CMake
based (I am using CMake 3.8 or 3.9 depending on the particular workstation that
I am using at the time) and also uses Qt 5.9.1 64 bit. All the code is C++.
What will happen is that I load the project, QtCreator properly configures for
the build (Debug) and I build the project successfully. I quit QtCreator.
Relaunch QtCreator and when I click Debug for our application QtCreator will
pretty much rebuild the entire project. NOTHING changed between when I last
built, quit QtCreator and relaunched QtCreator. I use ninja as the build tool.
When you open the project, then cmake will go through the
configure/generate steps again. Is that what you are referring to?
That is how cmake wants this to be handled, so there is nothing I can
do there.
Or does the actual build rebuild huge parts of the project? That could
be triggered by cmake configur/generate mentioned above: Do you create
some central header file or something from cmake? That would be a bug
that I'd need to file with upstream cmake:-/
Best Regards,
Tobias
Tobias,
I am trying to figure out the difference between the following 2
workflows.
1:
+ From a terminal, configure project with CMake
+ Build project. [ All files are compiled ]
+ rerun CMake on the current build folder.
+ Build project. NO files are rebuilt. Ninja takes about 4 seconds to 4 run.
2:
+ Open QtCreator and "Open Project" by pointing at the Top Level
CMakeLists.txt file
+ QtCreator configures the project into a temp directory.
+ Click the "Build Project" Hammer Icon. QtCreator then reconfigures project
into the proper build directory and proceeds to build the entire project.
+ Quit QtCreator.
+ Open QtCreator and load the project. QtCreator loads the project by running
CMake again on the build directory.
+ Click the Hammer Icon to build the project. A VERY Large portion of the
project is rebuilt (1100 files out of 1900 files total).
I can't get this to recreate often. I had it happen on my macOS machine when I
was running QtCreator 4.3 a lot. That seems to have settled down but then I had
it happen yesterday on my Windows 10, running VS2015 tooling with Ninja as the
build system. CMake version on the Windows 10 machine was 3.8.x.
And yes, I do create more than a few header files that are included in many of
the files BUT I wrote specific CMake code to generate the header into a temp
file, compare that file with any existing file via an MD5 hash and if the
contents are different only then is the new header file copied into place. I
did this specifically because I was having this same issue with *all* the build
systems that I was using.
Is QtCreator doing any kind of file stat or file copy before/during/after the
CMake phase? I just can not figure out what is triggering the full builds.
Thanks
Mike Jackson
PS: I like the adjustments to the CMake projects in QtCreator 4.4. Easier to
navigate around the project structure.
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