because I have a project that mixes C and Fortran, and compiling the C part with icc 12 and then the rest with ifort 11.1 gives some errors like this:
mumps_io_basic.c:(.text+0xc9): undefined reference to `__intel_sse2_strcpy'
and I can not use ifort 12.0 because it has a bug that affects the compilation of my code.
Mixing libraries of two major releases are not supported because we may introduce incompatibility features in new major release.
this symbol is from 12.0 "libirc.lib". you can link it to see if it solves the problem. But you may get run-time problems.
Note again: this is not supported.