/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/ is in golang-golang-x-crypto-dev 1:0.0~git20170629.0.5ef0053-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_amd64.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_amd64.s
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_noasm.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_test.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_vectors_test.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/internal/
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/internal/chacha20/
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/internal/chacha20/chacha_generic.go
/usr/share/gocode/src/golang.org/x/crypto/chacha20poly1305/internal/chacha20/chacha_test.go