[CMake] how to find out the compiler ID of a compiler which doesn't link

[Alexander Neundorf]

On Tuesday 23 February 2010, Alexander Neundorf wrote:
> On Monday 22 February 2010, Brad King wrote:
> > Alexander Neundorf wrote:
> > > Hi,
> > >
> > > it seems the IAR C/C++ compiler for AVR cannot generate executables,
> > > but only object files, and the linker has to be called explcitely on
> > > the generated object files:
> > > ftp://ftp.iar.se/WWWfiles/avr32/guides/ocavr32.pdf
> > >
> > > Which says:
> > > iccavr32 myfile.c
> > > xlink myfile.r82 -s __program_start -f lnkavr32.xcl
> > >
> > > Can this be made to work with the compiler ID detection in cmake via
> > > compiling a source file or is the only chance to use the new
> > > CMAKE_DETERMINE_COMPILER_ID_VENDOR() function ?
> >
> > It doesn't have to link.  We can parse the compiler id out of object
> > files. Look at lines in CMakeDetermineCCompiler that set
> >
> >   CMAKE_C_COMPILER_ID_TEST_FLAGS
> >
> > We already try compiling with just "-c" to get an object file.  Add the
> > equivalent flag for this compiler if necessary.  Basically we just try
> > with no flag, and then with each of the flags listed in this variable.
> > After each build we scan all files for the compiler id.  If the object
> > file is there it should work.
>
> This is for the AIR compiler, and it produces an IAR .r90 file.
> CMake tries to find the string in that file, but doesn't find it.
>
> Here (http://public.kitware.com/Bug/view.php?id=10176) such a file is
> attached (main.r90), and now I actually found the text in it :-)
> http://public.kitware.com/Bug/file_download.php?file_id=2896&type=bug
>
> Near the end there is the "Hello world", but mixed with "6"s. Very strange.

It seems this file format might be the "UBROF" format. But I also didn't find 
any documentation on that.
I'm thinking about just taking the binary object file, then appending all even 
bytes to it, and then appending all odd bytes to it. Then the interesting 
strings should be *somewhere* there.
Any better ideas ?

Alex