MantisBT - CMake
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ID	Project	Category	View Status	Date Submitted	Last Update
0014252	CMake	(No Category)	public	2013-06-28 09:13	2016-06-10 14:31

Reporter	Mojca Miklavec
Assigned To	Kitware Robot
Priority	normal	Severity	minor	Reproducibility	always
Status	closed	Resolution	moved
Platform	x86_64-darwin	OS	Mac OS X	OS Version	10.7.5
Product Version	CMake 2.8.10.2
Target Version		Fixed in Version

Summary	0014252: Unsupported "-arch x86_64" mysteriously ends up in Fortran_FLAGS
Description	http://public.kitware.com/pipermail/cmake-developers/2013-January/006230.html [^] An unsupported compiler flag "-arch x86_64" mysteriously sneaks into Fortran_FLAGS when -DCMAKE_OSX_ARCHITECTURES="x86_64" is passed to cmake. That flag CMAKE_OSX_ARCHITECTURES is added automatically to all projects in MacPorts (third-party package manager for Mac OS X) even when cross-compiling or compilation of fat binaries (like i386+x86_64) is not needed, so no project that needs Fortran and CMake can be compiled (luckily there are not many such projects, but it's still a showstopper to switch to CMake). The g95 compiler ignores "-arch <...>" flag, but GCC's gfortran 4.x throws an error and breaks compilation. I could probably try to prevent DCMAKE_OSX_ARCHITECTURES from being passed to cmake (via some tricks in MacPorts or by modifying MacPorts sources), but I still believe that passing "-arch x86_64" to Fortran_FLAGS is a bug in CMake.
Steps To Reproduce	Compiled Root (root.cern.ch) or any minimal project which needs Fortran with cmake \ -DCMAKE_Fortran_COMPILER=/opt/local/bin/gfortran-mp-4.5 \ -DCMAKE_C_COMPILER=/usr/bin/clang \ -DCMAKE_CXX_COMPILER=/usr/bin/clang++ \ -DCMAKE_INSTALL_PREFIX=/path/to/install \ -DCMAKE_OSX_ARCHITECTURES="x86_64" ../path/to/sources In that particular project the generated file misc/minicern/CMakeFiles/minicern.dir/flags.make ends up containing the following variables (among others): C_FLAGS = -m64 -pipe -W -Wall -fsigned-char -fno-common -O2 -g-arch x86_64 -fPIC -I<path/to/some/include/dirs> Fortran_FLAGS = -m64 -std=legacy -arch x86_64 -fPIC -I<path/to/some/include/dirs> The flag "-arch x86_64" shouldn't be there.
Additional Information	Citing http://public.kitware.com/pipermail/cmake-developers/2013-January/006230.html [^] The "-arch" flag is hard-coded here: http://cmake.org/gitweb?p=cmake.git;a=blob;f=Source/cmLocalGenerator.cxx;hb=v2.8.10.2#l1826 [^] It was added to CMake way back when universal binary support was first added to OS X under the assumption that all compilers that would be used in combination with CMAKE_OSX_ARCHITECTURES would support the flag. Obviously the assumption is wrong. The hard-coded flag needs to be replaced with a lookup of a new per-language platform information variable, perhaps called CMAKE_<LANG>_OSX_ARCHITECTURE_FLAG -Brad Some more links: - https://trac.macports.org/ticket/37732 [^] (about the -arch flag in Fortran) - https://trac.macports.org/ticket/37688 [^] ([also] about development of a package for Root using CMake) - https://sft.its.cern.ch/jira/browse/ROOT-4874 [^] (not strictly related)
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Issue History
Date Modified	Username	Field	Change
2013-06-28 09:13	Mojca Miklavec	New Issue
2013-06-28 09:28	Brad King	Additional Information Updated	bug_revision_view_page.php?rev_id=1203#r1203
2013-06-28 09:31	Brad King	Note Added: 0033397
2016-06-10 14:29	Kitware Robot	Note Added: 0042305
2016-06-10 14:29	Kitware Robot	Status	new => resolved
2016-06-10 14:29	Kitware Robot	Resolution	open => moved
2016-06-10 14:29	Kitware Robot	Assigned To	=> Kitware Robot
2016-06-10 14:31	Kitware Robot	Status	resolved => closed

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