var golang.org/x/tools/internal/gcimporter.pkgExts
2 uses
golang.org/x/tools/internal/gcimporter (current package)
gcimporter.go#L78: var pkgExts = [...]string{".a", ".o"}
gcimporter.go#L139: for _, ext := range pkgExts {
The pages are generated with Golds v0.4.9. (GOOS=linux GOARCH=amd64)