I have dev-lang/rust-1.30.1-r1 and virtual/cargo-1.30.1 installed here. Installing firefox and thunderbird both fail with 0:04.77 checking rustc version... 1.30.1 0:04.77 ERROR: Cargo package manager not found. qlist dev-lang/rust showed that there is (only) the binary /usr/bin/cargo-1.30.1 By adding a symlink in /usr/bin ln -s cargo-1.30.1 cargo I could fix the problem. Probably, that's a bug in dev-lang/cargo.
Yes, it is already reported in Bug 671182
Set the rust version new via `eselect rust set rust-1.30.1` fixed the issue :)
*** This bug has been marked as a duplicate of bug 671182 ***
Same problem here. On several up to date Gentoo unstable amd64. This did not help, as it was already set: eselect rust set rust-1.30.1 But this worked for me: ln -s cargo-1.30.1 cargo