/usr/share/gocode/src/golang.org/x/crypto/sha3/ is in golang-golang-x-crypto-dev 1:0.0~git20170407.0.55a552f+REALLY.0.0~git20161012.0.5f31782-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/gocode/src/golang.org/x/crypto/sha3/doc.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/hashes.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/keccakf.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/keccakf_amd64.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/keccakf_amd64.s
/usr/share/gocode/src/golang.org/x/crypto/sha3/register.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/sha3.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/sha3_test.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/shake.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/testdata/
/usr/share/gocode/src/golang.org/x/crypto/sha3/testdata/keccakKats.json.deflate
/usr/share/gocode/src/golang.org/x/crypto/sha3/xor.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/xor_generic.go
/usr/share/gocode/src/golang.org/x/crypto/sha3/xor_unaligned.go