Go build: “Cannot find package” (even though GOPATH is set)

Question

Even though I have GOPATH properly set, I still can\'t get \"go build\" or \"go run\" to find my own packages. What am I doing wrong?

$ echo $GO         


        

Answer 1

Edit: since you meant GOPATH, see fasmat's answer (upvoted)

As mentioned in "How do I make go find my package?", you need to put a package xxx in a directory xxx.

See the Go language spec:

package math

A set of files sharing the same PackageName form the implementation of a package.
An implementation may require that all source files for a package inhabit the same directory.

The Code organization mentions:

When building a program that imports the package "widget" the go command looks for src/pkg/widget inside the Go root, and then—if the package source isn't found there—it searches for src/widget inside each workspace in order.

(a "workspace" is a path entry in your GOPATH: that variable can reference multiple paths for your 'src, bin, pkg' to be)

---

(Original answer)

You also should set GOPATH to ~/go, not GOROOT, as illustrated in "How to Write Go Code".

The Go path is used to resolve import statements. It is implemented by and documented in the go/build package.

The GOPATH environment variable lists places to look for Go code.
On Unix, the value is a colon-separated string.
On Windows, the value is a semicolon-separated string.
On Plan 9, the value is a list.

That is different from GOROOT:

The Go binary distributions assume they will be installed in /usr/local/go (or c:\Go under Windows), but it is possible to install them in a different location.
If you do this, you will need to set the GOROOT environment variable to that directory when using the Go tools.

Answer 2

To be able to find your project's packages without installing it, (which is common during development), simply append project path to GOPATH.

• In terminal (Linux):
  First run: GOPATH=$GOPATH:/path/to/project
  Then go run main.go should be able to find packages from the project itself.
  Similar for Mac; for Windows the delimiter is ; not :.
• In Goland:
  Settings -> Go -> GOPATH, under Project GOPATH, add project path.
  Then Goland should be able to find packages from the project itself during development.

Answer 3

If you have a valid $GOROOT and $GOPATH but are developing outside of them, you might get this error if the package (yours or someone else's) hasn't been downloaded.

If that's the case, try go get -d (-d flag prevents installation) to ensure the package is downloaded before you run, build or install.