[Cmake] Determining host compiler/OS from CMake

[Ian Scott]

I don't know how useful adding detailed compiler support to CMakeLists.txt
is.
Either your compiler options are the default ones set by cmake, or you can
set them manually.

Where I do think there is a problem is the inability to set options for
single .cxx file. I have a file in VXL that doesn't compile properly with
gcc 2.95. The problem is exhibited in a subtle lack of IEEE rounding
conformity. I can use some of gcc's -f options to fiddle with the code out
and make it go away. These options have performance implications and so I
only want to run them for one file.
Currently I run the compiler by hand over that file, and then set it read
only, so that I don;t accidently compile over it.
My ideal solution (short of getting a better compiler) would be to modify
the relevant CMakeLists.txt file so that it included an optional
CMakeListsLocal.txt file. I could then check the CMakeLists.txt file into
the VXL repository. My CMakeListsLocal.txt file would contain an option to
modify the compiler options on my problematic .cxx file.

I don't plan to implement this :-(

Ian.

> -----Original Message-----
> From: Andy Cedilnik [mailto:Andy.Cedilnik at kitware.com]
> Sent: Thursday, February 28, 2002 5:15 PM
> To: Bill Hoffman; Parag Chandra; cmake at public.kitware.com
> Subject: Re: [Cmake] Determining host compiler/OS from CMake
>
>
> At 11:53 AM 2/28/2002 -0500, Bill Hoffman wrote:
> >Short answer: No, currently there is not.
> >
> >>Is there a predefined Cmake variable that I can use to
> determine the
> >>compiler and/or the operating system that Cmake is running
> under? I d
> >>like Cmake to be able to set some flags via the
> ADD_DEFINITIONS command
> >>using this information.
>
> Not to want to start the flame fights, but it may be a good
> idea to add
> some minimal support for getting compiler information in CMake.
> I mean, you can always do things in your C files and determine
> what compiler it is, but we could have something like:
> CMAKE_CXX_COMPILER_TYPE, which would say something like
> gcc,  hpux-aCC,  msvc, or bcc. This way developer could do some
> tricks inside CMake versus inside source files.
>
> There is a "hacky" way of determining certain things already. For
> example you can say IF(BORLAND) for borland or IF(WIN32) IF(UNIX)
> for cygwin and so on.
>
> So, simple mechanism for describing compiler and platform:
>
> COMPILER_TYPE=gcc
> COMPILE_PLATFORM=win32
> = cygwin
>
> Comments?
>
>                          Andy
>
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