c:\Users\Alex\dev\go\src>go tool compile -e %GOROOT%\test\fixedbugs\bug345.dir\main.go
c:\users\alex\dev\go\test\fixedbugs\bug345.dir\main.go:11:2: import path contains invalid character ':': "c:/Users/Alex/dev/go/src/io"
c:\users\alex\dev\go\test\fixedbugs\bug345.dir\main.go:25:8: undefined: io
c:\users\alex\dev\go\test\fixedbugs\bug345.dir\main.go:28:2: undefined: io

c:\Users\Alex\dev\go\src>

c:\Users\Alex\dev\go\src>type c:\users\alex\dev\go\test\fixedbugs\bug345.dir\main.go
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
        "bufio"
        goio "io"

        "./io"
)

func main() {
        // The errors here complain that io.X != io.X
        // for different values of io so they should be
        // showing the full import path, which for the
        // "./io" import is really ..../go/test/io.
        // For example:
        //
        // main.go:25: cannot use w (type "/Users/rsc/g/go/test/fixedbugs/bug345.dir/io".Writer) as type "io".Writer in function argument:
        //      io.Writer does not implement io.Writer (missing Write method)
        // main.go:27: cannot use &x (type *"io".SectionReader) as type *"/Users/rsc/g/go/test/fixedbugs/bug345.dir/io".SectionReader in function argument

        var w io.Writer
        bufio.NewWriter(w) // ERROR "[\w.]+[^.]/io|has incompatible type"
        var x goio.SectionReader
        io.SR(&x) // ERROR "[\w.]+[^.]/io|has incompatible type"
}

c:\Users\Alex\dev\go\src>

        "./io"

        "c:/Users/Alex/dev/go/src/io"

$GOPATH\golang\go\test>ver

Microsoft Windows [Version 10.0.18362.418]

$GOPATH\golang\go\test>go version
go version go1.13.3 windows/amd64

$GOPATH\golang\go\test>go run run.go -- fixedbugs/bug345.go

$GOPATH\Google\golang\go\test>goissue run run.go -- fixedbugs/bug345.go

$GOPATH\golang\go\test>