I am trying to compile boost with gcc-4.7 on FreeBSD-10.
I added USE_GCC=4.7 to Makefile.

Build fails:

###
### Using 'gcc' toolset.
###
rm -rf bootstrap
mkdir bootstrap
gcc47 -o bootstrap/jam0 command.c compile.c constants.c debug.c function.c glob.c hash.c hdrmacro.c headers.c jam.c jambase.c jamgram.c lists.c make.c make1.c object.c option.c output.c parse.c pathunix.c regexp.c rules.c scan.c search.c subst.c timestamp.c variable.c modules.c strings.c filesys.c builtins.c pwd.c class.c native.c md5.c w32_getreg.c modules/set.c modules/path.c modules/regex.c modules/property-set.c modules/sequence.c modules/order.c execunix.c fileunix.c
./bootstrap/jam0 -f build.jam --toolset=gcc --toolset-root= clean
...found 1 target...
...updating 1 target...
...updated 1 target...
./bootstrap/jam0 -f build.jam --toolset=gcc --toolset-root=
...found 50 targets...
...updating 3 targets...
[MKDIR] bin.freebsdx86_64
[COMPILE] bin.freebsdx86_64/b2
gcc: not found

    "gcc"   -o bin.freebsdx86_64/b2 "-DNDEBUG" "-DOPT_HEADER_CACHE_EXT" "-DOPT_GRAPH_DEBUG_EXT" "-DOPT_SEMAPHORE" "-DOPT_AT_FILES" "-DOPT_DEBUG_PROFILE" "-DOPT_FIX_TARGET_VARIABLES_EXT" "-DOPT_IMPROVED_PATIENCE_EXT" "-DYYSTACKSIZE=5000" "-pedantic" "-fno-strict-aliasing" "-s" "-O3" "-Wno-long-long" "command.c" "compile.c" "constants.c" "debug.c" "function.c" "glob.c" "hash.c" "hcache.c" "headers.c" "hdrmacro.c" "jam.c" "jambase.c" "jamgram.c" "lists.c" "make.c" "make1.c" "mem.c" "object.c" "option.c" "output.c" "parse.c" "regexp.c" "rules.c" "scan.c" "search.c" "subst.c" "w32_getreg.c" "timestamp.c" "variable.c" "modules.c" "strings.c" "filesys.c" "builtins.c" "pwd.c" "class.c" "native.c" "md5.c" "modules/set.c" "modules/path.c" "modules/regex.c" "modules/property-set.c" "modules/sequence.c" "modules/order.c" "execunix.c" "fileunix.c" "pathunix.c"

...failed [COMPILE] bin.freebsdx86_64/b2...
...skipped bjam for lack of b2...
...failed updating 1 target...
...skipped 1 target...


As you see, it first uses "gcc47" but then tries to use just "gcc" which is not
present on FreeBSD-10 at all.

Seems that it does not honor $CXX correctly.