MantisBT - CMake
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IDProjectCategoryView StatusDate SubmittedLast Update
0012652CMakeCMakepublic2012-01-03 15:492016-06-10 14:31
ReporterSean McBride 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
PlatformOSOS Version
Product VersionCMake 2.8.7 
Target VersionFixed in Version 
Summary0012652: CMAKE_<LANG>_FLAGS are passed for linking too, but this causes warnings for compilation-only flags
DescriptionSearching the archives, I see that CMake deliberately passes the CMAKE_<LANG>_FLAGS for linking too:

<http://www.cmake.org/pipermail/cmake/2010-July/038090.html> [^]

If I add -std=c++0x to CMAKE_CXX_FLAGS, then compilation is fine, but clang will warn when linking:

clang-3: warning: argument unused during compilation: '-std=c++0x'

For one's own projects, one could do something like:

SET_SOURCE_FILES_PROPERTIES(${MYCPPS} PROPERTIES COMPILE_FLAGS --std=c++0x)

But my hope was to use --std=c++0x on my CMake/VTK/ITK dashboards to make sure their codebases are foreword-compatible with the new language standard.

Above all, it seems weird that something named CMAKE_C_FLAGS is passed to the linker when we already have CMAKE_EXE_LINKER_FLAGS and the like.

I realize changing this has compatibility implications.
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Issue History
Date ModifiedUsernameFieldChange
2012-01-03 15:49Sean McBrideNew Issue
2012-01-03 16:23David ColeTarget Version => CMake 2.8.8
2012-01-03 16:32Brad KingNote Added: 0028151
2012-02-21 16:07David ColeStatusnew => backlog
2012-04-19 08:41David ColeTarget VersionCMake 2.8.8 =>
2012-04-19 08:42David ColeNote Added: 0029233
2012-10-18 04:35Amine ChadlyNote Added: 0031257
2016-06-10 14:28Kitware RobotNote Added: 0041952
2016-06-10 14:28Kitware RobotStatusbacklog => resolved
2016-06-10 14:28Kitware RobotResolutionopen => moved
2016-06-10 14:28Kitware RobotAssigned To => Kitware Robot
2016-06-10 14:31Kitware RobotStatusresolved => closed

Notes
(0028151)
Brad King   
2012-01-03 16:32   
We have always had to pass compilation flags to the compiler front-end when using it for linking. It matters at least for C++ because some compilers actually do real compilation at link time to do template instantiation (pre-linker). Since we've always done it for that reason we don't know where else it matters.

The behavior would have to be configured on a per-flag, per-toolchain basis. This is non-trivial. It really requires the long-requested feature of abstracting all optional behavior into properties that get mapped to flags as implementation details.
(0029233)
David Cole   
2012-04-19 08:42   
Unset target version... This is not going to change unless somebody has a concrete proposal that "fixes it" but also preserves backward compatibility for the cases where the flags are required for linking...
(0031257)
Amine Chadly   
2012-10-18 04:35   
What do you think of using a CMAKE_COMPILE_FLAGS_TO_LINKER or whatever cooler name you can come up with ? We could use it as a Boolean (true by default to keep today's behavior) that appends (or not) the compiler flags to the linker

Or we could use CMAKE_COMPILE_AND_LINK_FLAGS to specify flags that would be appended to both CMAKE_CXX_FLAGS and CMAKE_EXE_LINKERS_FLAGS.

Hope this helps.
(0041952)
Kitware Robot   
2016-06-10 14:28   
Resolving issue as `moved`.

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