MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0012286CMakeCMakepublic2011-06-19 13:082011-06-20 13:26
ReporterJérôme Gardou 
Assigned To 
PrioritynormalSeveritytweakReproducibilityalways
StatusclosedResolutionno change required 
PlatformMinGW - ccacheOSWindowsOS Version
Product VersionCMake 2.8.4 
Target VersionFixed in Version 
Summary0012286: Includes should be with unix path style when CMAKE_<LANG>_USE_RESPONSE_FILE_FOR_INCLUDES is set
DescriptionFor the reactos progject, we would like to use ccache to speed up compilation.

Unfortunately, cmake uses Response files to set includes of source files (like @Cmakefiles/target.dir/includes_C.rsp) and ccache doesn't support that.

Fortunately, we can set the CMAKE_<LANG>_USE_RESPONSE_FILE_FOR_INCLUDES variable to OFF and cmake will stop generating such files and will concatenate them to the flags. But it will use the windows path style, ie -IX:\some\path\to\some\header.h which is wrong.

You could as well use unix path style, or double backslashes. Please find the attached patch. This shouldn't break anything, all compiler I know of support the "/" path separator.
Steps To ReproduceCreate any module with MinGW (no need to use ccache) with the CMAKE_C_USE_RESPONSE_FILE_FOR_INCLUDES set to OFF, and see the result.
Additional Information
TagsNo tags attached.
Relationships
Attached Filespatch 0002-Use-unix-path-style-for-includes-when-CMAKE_-LANG-_U.patch (857) 2011-06-19 13:08
https://public.kitware.com/Bug/file/3949/0002-Use-unix-path-style-for-includes-when-CMAKE_-LANG-_U.patch
Issue History
Date ModifiedUsernameFieldChange
2011-06-19 13:08Jérôme GardouNew Issue
2011-06-19 13:08Jérôme GardouFile Added: 0002-Use-unix-path-style-for-includes-when-CMAKE_-LANG-_U.patch
2011-06-20 09:04Brad KingStatusnew => backlog
2011-06-20 09:15Brad KingNote Added: 0026914
2011-06-20 11:52Jérôme GardouNote Added: 0026916
2011-06-20 11:52Brad KingNote Added: 0026917
2011-06-20 11:53Brad KingNote Edited: 0026917bug_revision_view_page.php?bugnote_id=26917#r364
2011-06-20 11:58Jérôme GardouNote Added: 0026919
2011-06-20 12:01Brad KingNote Added: 0026920
2011-06-20 12:37Jérôme GardouNote Added: 0026921
2011-06-20 12:54Jérôme GardouNote Edited: 0026921bug_revision_view_page.php?bugnote_id=26921#r368
2011-06-20 13:26Brad KingNote Added: 0026922
2011-06-20 13:26Brad KingStatusbacklog => closed
2011-06-20 13:26Brad KingResolutionopen => no change required

Notes
(0026914)
Brad King   
2011-06-20 09:15   
We started using response files for include paths here:

  http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=9a0b9bc8 [^]
  http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=86cb17b1 [^]

because some projects use really long include path lists that the mingw32-make shell could not handle.

Patch 0002-Use-unix-path-style-for-includes-when-CMAKE_-LANG-_U.patch modifies AddIncludeFlags which is only about the final command line generation. Path conversion has already taken place by that point so converting it back is incorrect. CMake stores all paths internally using forward slashes. Then the generators convert to the proper slashes at the end.

The cmLocalGenerator::GetIncludeFlags method calls Convert methods to format file paths for generation into the build system. It is not wrong to use backslashes in this context. The flags appear on a command line for a *Windows* shell inside mingw32-make.
(0026916)
Jérôme Gardou   
2011-06-20 11:52   
OK, but then it should use x:\\some\\Path, as doing otherwise breaks compilation. IMHO, all windows path should be defined that way.
(0026917)
Brad King   
2011-06-20 11:52   
(edited on: 2011-06-20 11:53)
Does it break compilation without ccache? We've been using backslashes in this generator for YEARS and never seen a problem.
(0026919)
Jérôme Gardou   
2011-06-20 11:58   
Good point, if you don't experience any problem, then it's likely to be ccache fault. I guess I'll have to work a patch on their side. Thanks for pointing this out.

BTW, what about using some make variable such as C_INCLUDES (along with C_FLAGS and C_DEFINES) defined in flags.make instead of adding yet another file dependency? This way you wouldn't need any gcc 3.x special variable.
(0026920)
Brad King   
2011-06-20 12:01   
C_INCLUDES instead of response files? The reason for the response file is not a limitation of the make tool. The windows command line cannot exceed 32K bytes or so (I think it is a CreateProcess API limitation). Projects with really long paths to their source/build trees and lots of include directories cannot build unless the long lists are left out of the command line invocation.
(0026921)
Jérôme Gardou   
2011-06-20 12:37   
(edited on: 2011-06-20 12:54)
OK... Anyway, thanks for pointing me in the right direction. I guess you can close the bug now.

EDIT : btw, if you look at the response file, you'll notice that paths are unix-styled. That's what made me think it was a cmake bug.
(0026922)
Brad King   
2011-06-20 13:26   
Re 0012286:0026921: The response files use forward slashes because that is what gcc's documentation requires. I understand the confusion. Good discussion.