[CMake] Setting environment variables prebuild

[Kito Berg-Taylor]

Thanks for the quick reply,

The main reason why setting the environment variables by hand is not a
clean solution is that setting environment variables globally on windows
machines requires administrator privileges. I'm sure I could get the
environment variables set on all our build machines, but this is an
unwelcome hassle that will introduce problems every time a new machine
is added into the build process. If such functionality does not already
exist, I proposeg the following (and would be willing to submit a patch
if there is interest):

When SET( ENV{FOO} bar ) is found in a CMake file, add the following to
the project files:

For Unix Makefiles simply defining a macro with the variables name
should be sufficient. So 

FOO := bar

It should be able to do the same in most other generated projects, for
example in eclipse one could add the following to the .project:

<dictionary>
	<key>org.eclipse.cdt.make.core.environment</key>
	<value>FOO=bar</value>
</dictionary>

however, I don't believe this should be necessary, since eclipse just
invokes the makefile, which should then work correctly.

On a side note, when testing this I noticed that this worked fine for
the QNX_HOST and QNX_TARGET variables, but setting PATH in this manner
seemed to have no effect (WinXP, GNU Make).

-kito

On Tue, 2009-03-03 at 09:32 -0600, kent williams wrote:
> You're not missing anything per se.  If you set environment variables
> in your CMakeLists.txt file for some operations it's just too late. In
> particular, it doesn't add commands to the build files it generates to
> set the environment variables the way you need them.
> 
> You can get around this -- I think -- by setting the QNX environment
> variables before you run CMake, and making sure they're set before you
> try and build or use Eclipse.  CMake also will honor CXX, CC, CXXFLAGS
> and CFLAGS environment variables, using them to initialize the
> corresponding CMAKE variables.
> 
> This is the sort of squirrelly messing about that is an inevitable
> part of being a software developer. That's why they pay you the big
> bucks.
> 
> On Tue, Mar 3, 2009 at 9:13 AM, Kito Berg-Taylor
> <kito.berg-taylor at dlr.de> wrote:
> > Hello all,
> >
> > I'm very new to cmake, so excuse me if I'm missing some obvious
> > functionality that cmake already has.
> >
> > I am building a project using a QNX cross-compile toolchain that I
> > setup. For those not familiar with the QNX toolchain, the QNX compiler
> > qcc is a wrapper around gcc that's mostly the same but has a few
> > peculiarities. Of particular relevance, it requires QNX_HOST and
> > QNX_TARGET (and QNX_CONFIGURATION on win32) to be set as environment
> > variables. I have setup my toolchain_qnx640.cmake file to automatically
> > locate the $QNX_HOST (...etc) path and then set it as follows:
> >
> > SET( ENV{QNX_HOST} ${PATH_TO_QNX_HOST} )
> >
> > This allows the configure/generate steps to work correctly, however when
> > I go to build the project unless these variables are set separately in
> > the environment, the build will fail. In other words, CMake is not
> > setting this variable as part of the build (although it did set them
> > when it went to test the compiler, because qcc passed the compiler
> > test).
> >
> > When building from UNIX Makefiles I can set the variable at the console
> > and then "make" and it will work. When using Codeblocks projects if (and
> > only if) I change the project compiler to QCC Compiler it will also
> > build, since Codeblocks knows how to setup the environment for QCC. I
> > can't find a way to make QCC the default compiler when generating the
> > project (otherwise this will get overridden every time the project is
> > re-generated). Eclipse CDT projects similarly won't build, unless I mess
> > around with the project settings (new to eclipse, haven't found the
> > right settings yet).
> >
> > Am I missing something? Is this a bug/design choice?
> >
> > I realize that the simple answer is to just set these environment
> > variables on the machines before building, but this is not always
> > possible (and shouldn't be necessary).
> >
> > I've included the toolchain_qnx640.cmake file below in case it makes
> > things a little clearer. I welcome any input...
> >
> > SET( CMAKE_SYSTEM_NAME Qnx )
> > SET( CMAKE_SYSTEM_VERSION 6.4.0 )
> > SET( CMAKE_SYSTEM_PROCESSOR x86 )
> > SET( TOOLCHAIN QNX )
> >
> > # used to help us find the programs
> > # CMAKE_EXECUTABLE_SUFFIX wasn't working
> > # because it found the target suffix, which
> > # is not what we want here
> > IF( CMAKE_HOST_WIN32 )
> >  SET( HOST_EXECUTABLE_SUFFIX ".exe" )
> > ENDIF( CMAKE_HOST_WIN32 )
> >
> > # see if we can find QNX_HOST and QNX_TARGET
> > # this is not the most intelligent search, but it should
> > # serve our purposes for now
> > FIND_PATH( QNX_HOST
> >  NAME usr/bin/qcc${HOST_EXECUTABLE_SUFFIX}
> >  PATHS $ENV{QNX_HOST} C:/Programme/CodeBlocks/QNXSDK630/host/win32/x86
> >  NO_CMAKE_PATH
> >  NO_CMAKE_ENVIRONMENT_PATH
> > )
> >
> > FIND_PATH( QNX_TARGET
> >  NAME usr/include/qnx_errno.h
> >  PATHS $ENV{QNX_TARGET} C:/Programme/CodeBlocks/QNXSDK630/target/qnx6
> >  NO_CMAKE_PATH
> >  NO_CMAKE_ENVIRONMENT_PATH
> > )
> >
> > # QNX_CONFIGURATION only exists in windows
> > IF( CMAKE_HOST_WIN32 )
> >  FIND_PATH( QNX_CONFIGURATION
> >    NAME bin/qnxactivate.exe
> >    PATHS $ENV{QNX_CONFIGURATION}
> > C:/Programme/CodeBlocks/QNXSDK630/config
> >    NO_CMAKE_PATH
> >    NO_CMAKE_ENVIRONMENT_PATH
> >  )
> > ENDIF( CMAKE_HOST_WIN32 )
> >
> > # export the QNX flags so that QNX can use them too
> > # this is necessary for qcc to work, otherwise it will
> > # complain about the license and missing QNX_HOST,QNX_TARGET
> > SET( ENV{QNX_HOST} ${QNX_HOST} )
> > SET( ENV{QNX_TARGET} ${QNX_TARGET} )
> > IF( CMAKE_HOST_WIN32 )
> >  SET( ENV{QNX_CONFIGURATION} ${QNX_CONFIGURATION} )
> >
> >  # cygwin1.dll needs to be in the PATH for qcc to run
> >  SET( ENV{PATH} "$ENV{PATH};${QNX_HOST}/usr/bin" )
> > ENDIF( CMAKE_HOST_WIN32 )
> >
> > # Find some basic programs
> > SET( CMAKE_MAKE_PROGRAM "${QNX_HOST}/usr/bin/make
> > ${HOST_EXECUTABLE_SUFFIX}"    CACHE PATH "QNX Make Program" )
> > SET( CMAKE_SH           "${QNX_HOST}/usr/bin/sh
> > ${HOST_EXECUTABLE_SUFFIX}"      CACHE PATH "QNX shell Program" )
> > SET( CMAKE_AR           "${QNX_HOST}/usr/bin/ntox86-ar
> > ${HOST_EXECUTABLE_SUFFIX}"      CACHE PATH "QNX ar Program" )
> > SET( CMAKE_NM           "${QNX_HOST}/usr/bin/ntox86-nm
> > ${HOST_EXECUTABLE_SUFFIX}"      CACHE PATH "QNX nm Program" )
> > SET( CMAKE_OBJCOPY      "${QNX_HOST}/usr/bin/ntox86-objcopy
> > ${HOST_EXECUTABLE_SUFFIX}" CACHE PATH "QNX objcopy Program" )
> > SET( CMAKE_OBJDUMP      "${QNX_HOST}/usr/bin/ntox86-objdump
> > ${HOST_EXECUTABLE_SUFFIX}" CACHE PATH "QNX objdump Program" )
> > SET( CMAKE_LINKER       "${QNX_HOST}/usr/bin/qcc
> > ${HOST_EXECUTABLE_SUFFIX}"     CACHE PATH "QNX Linker Program" )
> > SET( CMAKE_STRIP        "${QNX_HOST}/usr/bin/ntox86-strip
> > ${HOST_EXECUTABLE_SUFFIX}"   CACHE PATH "QNX Strip Program" )
> >
> > SET( CMAKE_C_COMPILER ${QNX_HOST}/usr/bin/qcc${HOST_EXECUTABLE_SUFFIX} )
> > SET( CMAKE_CXX_COMPILER ${QNX_HOST}/usr/bin/qcc
> > ${HOST_EXECUTABLE_SUFFIX} )
> >
> > SET( CMAKE_C_FLAGS "-Vgcc_ntox86 -w1" CACHE STRING "qcc c flags" FORCE )
> > SET( CMAKE_CXX_FLAGS "-Vgcc_ntox86 -lang-c++ -w1" CACHE STRING "qcc cxx
> > flags" FORCE )
> >
> > SET( CMAKE_FIND_ROOT_PATH ${QNX_TARGET} )
> > SET( CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER )
> > SET( CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY )
> > SET( CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY )
> >
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