cmd/go: emit better error message on improper use go "go install"

[gopherbot]

by dean.w.schulze:

go version go1.1.2 windows/amd64
(Also happens in go version go1.1 windows/amd64)

GOPATH (Cygwin):
c:\dean\golang\go3p:c:\dean\courses\algorithms-stanford\design.and.analysis.of.algorithms.1\programming-questions\common\code\golang

The file algoutils.go is in the directory 

c:\dean\courses\algorithms-stanford\design.and.analysis.of.algorithms.1\programming-questions\common\code\golang\src\algoutils

From that directory run

    go install algoutils.go

go install: no install location for directory
C:\dean\courses\algorithms-stanford\design.and.analysis.of.algorithms.1\programming-questions\common\code\golang\src\algoutils
outside GOPATH

I get the same error if I run from Cygwin or if I run from DOS.  The DOS GOPATH is

GOPATH=c:\dean\golang\go3p;c:\dean\courses\algorithms-stanford\design.and.analysis.of.algorithms.1\programming-questions\common\code\golang

In both cases (DOS and Cygwin) the command "go install algoutils" works.  It's
just an issue of the algoutils.go file is given as the input.

[gopherbot]

Comment 1 by dean.w.schulze:

Slight correction.  The GOPATH in Cygwin was
c:\dean\courses\algorithms-stanford\design.and.analysis.of.algorithms.1\programming-questions\common\code\golang
Only one directory in the GOPATH.
When creating the GOPATH in .bashrc for Cygwin the directories have to be separated by a
semi-colon not a colon since the DOS conventions have to be followed.
This doesn't change the issue with using a .go file as the argument to "go install".

[adg]

Comment 2:

The issue is a bad error message. "go install" takes a package path as its argument, not
.go source files. The entire concept of installation is tied to package paths.

Labels changed: added priority-later, removed priority-triage.

Status changed to Accepted.

[robpike]

Comment 3:

"go install file.go" works just fine if GOBIN is set. I will file a separate issue for
that.

[rsc]

Comment 4:

This issue was closed by revision 159c2b7.

Status changed to Fixed.