errcheck: Fails if anything uses cgo

This is probably a known limitation, but I couldn’t find a ticket for it, so here goes:

errcheck fails if a dependency uses cgo (has import "C").

Additionally, it seems impossible to ignore this lack of “C” via -ignorepkg (or I just don’t know how to use the thing).

[0 tv@brute ~/src/2013/errcheck-bug-cgo]$ ls
repro.go
[0 tv@brute ~/src/2013/errcheck-bug-cgo]$ cat repro.go 
package main

import _ "github.com/jmhodges/levigo"

func main() {
}
[0 tv@brute ~/src/2013/errcheck-bug-cgo]$ errcheck .
error:failed to check package: could not type check: repro.go:3:10: could not import github.com/jmhodges/levigo (/home/tv/go/src/github.com/jmhodges/levigo/conv.go:4:8: could not import C (cannot find package "C" in any of:
    /home/tv/src/go/src/pkg/C (from $GOROOT)
    /home/tv/go/src/C (from $GOPATH)))
[1 tv@brute ~/src/2013/errcheck-bug-cgo]$ errcheck -ignorepkg=github.com/jmhodges/levigo .
error:failed to check package: could not type check: repro.go:3:10: could not import github.com/jmhodges/levigo (/home/tv/go/src/github.com/jmhodges/levigo/cache.go:6:8: could not import C (cannot find package "C" in any of:
    /home/tv/src/go/src/pkg/C (from $GOROOT)
    /home/tv/go/src/C (from $GOPATH)))
[1 tv@brute ~/src/2013/errcheck-bug-cgo]$ errcheck -ignorepkg=C .
error:failed to check package: could not type check: repro.go:3:10: could not import github.com/jmhodges/levigo (/home/tv/go/src/github.com/jmhodges/levigo/iterator.go:6:8: could not import C (cannot find package "C" in any of:
    /home/tv/src/go/src/pkg/C (from $GOROOT)
    /home/tv/go/src/C (from $GOPATH)))
[1 tv@brute ~/src/2013/errcheck-bug-cgo]$