by russel.winder:

When installing packages, the default compiler uses a directory that identifies the
platform of the installed: for example, $GOPATH/package/linux_amd64 on a 64-bit Linux
machine. GCCGo on the other hand simply uses $GOPATH/pkg/gccgo. For a filestore shared
by multiple machines with heterogenous platforms this leads to problems.

The standard compiler should perhaps include an identifier in the name ;

    $GOPATH/pkg/go_linux_amd64

and then GCCGo should use:

    $GOPATH/pkg/gccgo_linux_amd64