Unable to locate 'gcc' on Snow Leopard during installation

--- This issue was originally reported by alec-c4 on github. Moved here verbatim. ---

Hi, on attempt to install webroar on osx snow leopard i see

bash-3.2# webroar install
Checking for the dependencies ...
Checking for ruby........found at /opt/local/bin/ruby.
Checking for libruby.1.8.7.dylib........found.
Checking for openssl-ruby........found.
Checking for zlib-ruby........found.
Checking for ruby_headers........found at /opt/local/lib/ruby/1.8/i686-darwin10/ruby.h.
Checking for rubygems........found.
Checking for /usr/bin/gcc-4.2........not found.
Unable to find /usr/bin/gcc-4.2 at any of these locations /opt/nginx/sbin,/opt/local/bin,/opt/local/sbin,/usr/bin,/bin,/usr/sbin,/sbin,/usr/local/bin,/usr/X11/bin,/usr/bin,/usr/sbin,/sbin,/usr/local/sbin,/opt/local/lib/ruby/gems/1.8/gems/webroar-0.2.3/bin
Checking for make........found at /usr/bin/make.
Checking for starling........found at /opt/local/bin/starling.
Checking for Xcode.app........found at /Developer/Applications/Xcode.app.
The following dependencies required for installation could not be found:
/usr/bin/gcc-4.2 Please refer the user guide for the list of prerequisites. Sorry, WebROaR could not be installed on this machine.

but

bash-3.2# gcc -v
Using built-in specs.
Target: i686-apple-darwin10
Configured with: /var/tmp/gcc/gcc-5646~6/src/configure --disable-checking --enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin10 --with-gxx-include-dir=/include/c++/4.2.1 --program-prefix=i686-apple-darwin10- --host=x86_64-apple-darwin10 --target=i686-apple-darwin10
Thread model: posix
gcc version 4.2.1 (Apple Inc. build 5646)
bash-3.2# whereis gcc
/usr/bin/gcc

how can i solve it?