cmd/doc: nearest-match package resolution not performed for type queries

[willfaught]

Please answer these questions before submitting your issue. Thanks!

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

go version go1.7.4 darwin/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/will.faught/Developer/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.7.4_2/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.7.4_2/libexec/pkg/tool/darwin_amd64"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/jt/c0hjffqj6gxbhy00gm0btzkr79h225/T/go-build032171883=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"

What did you do?

File $GOPATH/src/t/u/u.go:

package u

type U struct{}

func (u *U) M() {}

$ go doc u
package u // import "t/u"

type U struct { ... }
$ go doc u U

What did you expect to see?

$ go doc u U
type U struct{}

func (u *U) M()

What did you see instead?

$ go doc u U
doc: cannot find package "u" in any of:
	/usr/local/Cellar/go/1.7.4_2/libexec/src/u (from $GOROOT)
	/Users/will.faught/Developer/go/src/u (from $GOPATH)
exit status 1

[alexd765]

(Should get the prefix cmd/doc:)

This is related to #18664.

In the function parseArgs we spend a lot of effort to find the right thing for go doc with one argument, but we spend no effort for two arguments.

[bradfitz]

/cc @robpike

[robpike]

Looks like it should be fixed.

[willfaught]

Edited the description to correct the file path to be $GOPATH/src/t/u/u.go instead of $GOPATH/src/t/u.go (consistent with the package u // import "t/u" part).

[gopherbot]

Change https://golang.org/cl/59413 mentions this issue: cmd/doc: search for packages in the two-arg case