build-webkit: Don't remove CMakeFiles directory

• Component: CMake
• Status: RESOLVED FIXED

[Fujii Hironori]

[CMake][Win] ninja: error: build.ninja:35: loading 'CMakeFiles\rules.ninja': The system cannot find the file specified.

WinCairo and PlayStation builders are rarely observing the following error.

https://build.webkit.org/#/builders/731/builds/1945

> ninja: error: build.ninja:35: loading 'CMakeFiles\rules.ninja': The system cannot find the file specified.
> include CMakeFiles\rules.ninja
>                               ^ near here

[Fujii Hironori]

I don't know how this problem appears. But, it's easy to reproduce the error by removing WebKitBuild/{Debug,Release}/CMakeFiles directory manually.
However, this problem doesn't happen if I remove both CMakeFiles directory and CMakeCache.txt. It executes cmake to regenerate in such a case.
removeCMakeCache actually removes both. Weird.

https://github.com/WebKit/WebKit/blob/5a049809955a360f7ec43aa244acc1e65b4b70e6/Tools/Scripts/webkitdirs.pm#L2683-L2684

> unlink($cmakeCache) if -e $cmakeCache;
> rmtree($cmakeFiles) if -d $cmakeFiles;

[Fujii Hironori]

Steps to reproduce:

1. Invoke .\Tools\Scripts\build-webkit
   CMakeLists.txt and CMakeFiles directory are created.
2. Add "message(FATAL_ERROR)" to Source/cmake/OptionsCommon.cmake
3. Invoke .\Tools\Scripts\build-webkit
   CMakeLists.txt and CMakeFiles directory are removed.
   Only CMakeLists.txt is created.
4. Invoke .\Tools\Scripts\build-webkit
   Report the ninja error

[Fujii Hironori]

Bug#165008 introduced this bug.
And, CMake 3.8 fixed the CMake problem. 

https://gitlab.kitware.com/cmake/cmake/-/issues/13934#note_200624
https://gitlab.kitware.com/cmake/cmake/-/commit/25b6e7b710d7739cca44ed19bf45a190e72a6b82

I'm going to revert the WebKit change.

[Fujii Hironori]

Created attachment 465079 [details]
Patch

[Carlos Alberto Lopez Perez]

(In reply to Fujii Hironori from comment #4)
> Created attachment 465079 [details]
> Patch

I don't understand why or how this patch would work.

As far as I can see what CMake developers did on 3.8 was to also purge the CMakeFiles directory if the CMakeCache.txt file was removed, which is also basically what the current code in the script 'build-webkit' does.

So why patching the script 'build-webkit' to not remove the CMakeFiles directory fixes the problem? CMake is also supposed to remove this directory in any case, doesn't it?

I'm confused, sorry

[Fujii Hironori]

IIUC, it removes ${CMAKE_BINARY_DIR}/CMakeFiles/${CMAKE_VERSION} directory.
https://gitlab.kitware.com/cmake/cmake/-/blob/master/Source/cmGlobalGenerator.cxx#L584

rules.ninja is not removed becaused it is in ${CMAKE_BINARY_DIR}/CMakeFiles directory.

[Michael Catanzaro]

Comment on attachment 465079 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=465079&action=review

Fujii, I think you might be the only developer still attaching patches to Bugzilla. :P

> COMMIT_MESSAGE:11
> +And, the original CMake proglem was fixed by CMake 3.8.

problem

[Fujii Hironori]

Created attachment 465090 [details]
Patch

[Fujii Hironori]

Created attachment 465093 [details]
[fast-cq] Patch

[EWS]

Committed 260563@main (4e08fdf96101): <https://commits.webkit.org/260563@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 465093 [details].