rust-lang/rust — pull request #15971 by alexcrichton (2014-07-25 05:44:14+00:00)
Title: rustc: Compare paths with --extern, not bytes

The right hand side of the comparison in these checks are values of type
Option<&Path> which are normalized versions of the left-hand side, so they're
not guaranteed to be byte-for-byte equivalent even though they're the same path.

For this reasons, the command line arguments are promoted to paths for
comparison of equality.

This fixes a bug on windows where if a library was specified with --extern it
would then be picked up twice because it was not considered to have been
previously registered.