[CMake] Building a library for both C and C++

[kgardenia42]

Hi list,

I am trying to write a CMakeLists.txt where the same source files are
compiled separately to both a C library and a C++ library.

So, lets say I have foo.c, bar.c and baz.c and I would like to build
mylib.a and mylib++.a

My intuition is to use one CMakefile and add multiple targets for each
library I want to build.  Does that seem like a reasonable approach?
Other suggestions welcome.  Also, can anyone point me to an open
source library that uses cmake and builds both a C and C++ version.

If that approach (one CMakeLists.txt to build both libraries) seems
reasonable then how can I override the language per target?

I know that I can force the use of a C++ compiler for source files:

SET_SOURCE_FILES_PROPERTIES( ${mylib_SRCS} PROPERTIES LANGUAGE CXX )

However, this seems to set the language globally and so now all
targets use the C++ compiler.

I couldn't seem to figure out how to do the equivalent thing
per-target.  Any suggestions?  i.e. is there another way (other than
SET_SOURCE_FILES_PROPERTIES) which could accomplish the "set the
language per target" functionality I need here?

Thanks.