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gcc
Fedora 15 comes with GCC 4.6.0 as primary compiler. Users will be able to see compiled code improvements and use the newly added features, such as improved C++0x support, support for the Go language, REAL*16 support in Fortran, etc. See http://gcc.gnu.org/gcc-4.6/changes.html for user visible changes in it, and Features/GCC46