go mod does not work correctly

[jacking212]

What version of Go are you using (go version)?

$ go version
go version go1.12.1 linux/amd64

Does this issue reproduce with the latest release?

i am using the latest version download from golang.org/dl

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/jay/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/usr/local/lib/go/gopath"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/lib/go/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/lib/go/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/jay/workspace/goproject/modtest/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build438757086=/tmp/go-build -gno-record-gcc-switches"

What did you do?

i created a test project using go mod, but it got a mistakes when building.
the detail as follows:
main.go

package main
import(
    _ "golang.org/x/text"    
    _ "golang.org/x/crypto"    
    _ "golang.org/x/net"  
    _ "golang.org/x/sys"   
    "fmt"
)
// i had tried delete the imports, and found that only 'golang.org/x/text' could work correctly.

func main(){
    fmt.Println("x")
}

go.mod

module modtest

go 1.12

require (
        golang.org/x/crypto v0.0.0-20190320223903-b7391e95e576
        golang.org/x/net v0.0.0-20190324223953-e3b2ff56ed87
        golang.org/x/sys v0.0.0-20190322080309-f49334f85ddc
        golang.org/x/text v0.3.0
)
// the version of package was auto generated.   i set all latest before building the program.

What did you expect to see?

if it run correctly,it should print 'x'

What did you see instead?

[jay@jay modtest]$ go run main.go
go: finding golang.org/x/net latest
go: finding golang.org/x/crypto latest
build command-line-arguments: cannot load golang.org/x/crypto: cannot find module providing package golang.org/x/crypto

[jacking212]

the gopath files :

[jay@jay gopath]$ tree -L 5  
.
`-- pkg
    `-- mod
        |-- cache
        |   |-- download
        |   |   |-- github.com
        |   |   `-- golang.org
        |   |-- lock
        |   `-- vcs
        |       |-- 3d9b894478eea73fae540a3c6900133702ad88e0dbb703558d5c10d87962b8f1
        |       |-- 3d9b894478eea73fae540a3c6900133702ad88e0dbb703558d5c10d87962b8f1.info
        |       |-- 3d9b894478eea73fae540a3c6900133702ad88e0dbb703558d5c10d87962b8f1.lock
        |       |-- 4a22365141bc4eea5d5ac4a1395e653f2669485db75ef119e7bbec8e19b12a21
        |       |-- 4a22365141bc4eea5d5ac4a1395e653f2669485db75ef119e7bbec8e19b12a21.info
        |       |-- 4a22365141bc4eea5d5ac4a1395e653f2669485db75ef119e7bbec8e19b12a21.lock
        |       |-- 5b03666c2d7b526129bad48c5cea095aad8b83badc1daa202e7b0279e3a5d861
        |       |-- 5b03666c2d7b526129bad48c5cea095aad8b83badc1daa202e7b0279e3a5d861.info
        |       |-- 5b03666c2d7b526129bad48c5cea095aad8b83badc1daa202e7b0279e3a5d861.lock
        |       |-- 5c9bf7c1f1703ada412b15f25fe9823c0520278a873c6408060a99ea99e1f38e
        |       |-- 5c9bf7c1f1703ada412b15f25fe9823c0520278a873c6408060a99ea99e1f38e.info
        |       |-- 5c9bf7c1f1703ada412b15f25fe9823c0520278a873c6408060a99ea99e1f38e.lock
        |       |-- 60a9437416860492593650e193a1cf609f2902b80f52b9c964888a14bbb4be1c
        |       |-- 60a9437416860492593650e193a1cf609f2902b80f52b9c964888a14bbb4be1c.info
        |       |-- 60a9437416860492593650e193a1cf609f2902b80f52b9c964888a14bbb4be1c.lock
        |       |-- 76a8992ccba6d77c6bcf031ff2b6d821cf232e4ad8d1f2362404fbd0a798d846
        |       |-- 76a8992ccba6d77c6bcf031ff2b6d821cf232e4ad8d1f2362404fbd0a798d846.info
        |       |-- 76a8992ccba6d77c6bcf031ff2b6d821cf232e4ad8d1f2362404fbd0a798d846.lock
        |       |-- b7497faebb7c089572d87623a2670f0affcfebc950e7ccadab2b5959887cf2c3
        |       |-- b7497faebb7c089572d87623a2670f0affcfebc950e7ccadab2b5959887cf2c3.info
        |       |-- b7497faebb7c089572d87623a2670f0affcfebc950e7ccadab2b5959887cf2c3.lock
        |       |-- de5fd3af413a4f3f969455ae522b4002fcb7bb4c158f339396dfc77710c9007d
        |       |-- de5fd3af413a4f3f969455ae522b4002fcb7bb4c158f339396dfc77710c9007d.info
        |       `-- de5fd3af413a4f3f969455ae522b4002fcb7bb4c158f339396dfc77710c9007d.lock
        |-- github.com
        |   `-- golang
        |       |-- [email protected]
        |       |-- [email protected]
        |       `-- [email protected]
        `-- golang.org
            `-- x
                |-- [email protected]
                |-- [email protected]
                |-- [email protected]
                |-- [email protected]
                |-- [email protected]
                `-- [email protected]

[bcmills]

The error message here is correct. There is no importable package at the root of the golang.org/x/crypto module, and there is no other module providing such a package.