crabtw/rust — comment on commit ecd7d93c30acdf02fc95f5318e0657d3ac802837
File: src/comp/back/link.rs line 666
By crabtw:

libexecinfo provides backtrace, backtrace_symbols_fd functions. rustrt needs them.
The "-z origin" is to add the "origin" flag to. If this flag is missing, the $ORIGIN in rpath has no effect.

For /usr/local/lib/gcc46 etc, because I have some problems with the default gcc (4.2.1) of FreeBSD 8.2-Release,
I use newer gcc (4.6) to compile rustrt and rustllvm.
However, the compiled objects need some symbols that do not exist in old libstdc++.
I have to add extra library paths and rpaths to link with the new one because ld only looks /usr/lib and /usr/local/lib by default.
I add gcc44 and gcc46 paths because users may install either gcc44 or gcc46.

I hope these answer your questions.