go/parser: example for ParseFile fails on golang.org (playground)

[aaash99999]

Please answer these questions before submitting your issue. Thanks!

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

n/a (error is on golang.org)

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

n/a

What did you do?

Visit https://golang.org/pkg/go/parser/#example_ParseFile (specifically, the example for ParseFile).
Click Run to run the example.

What did you expect to see?

Output of the program.

What did you see instead?

open example_test.go: No such file or directory

Program exited.

[sgen]

The example is being run in the (Go Playground)[https://play.golang.org/]
which is run with various restrictions, including (filesystem restrictions)[https://blog.golang.org/playground#TOC_3.2.]. I dont think this example is supposed to run in the playground.

Does the example work when you copy it to a new package and include a valid 'example_test.go' file?

[mvdan]

The example depends on its own file in the go/parser package: https://golang.org/src/go/parser/

I guess a way to make it work in the playground would be for the example to first write a file to disk, or to use a buffer/string as the source.

[mvdan]

I'll write up a quick CL doing that.

[sgen]

In (Inside the Go Playground)[https://blog.golang.org/playground] its mentioned that zip files may be uploaded for the purpose of examples. Perhaps uploading example_test.go is a better solution?

[mvdan]

I think that's a bit overkill. If the purpose of the example was precisely to use a file via filename and not a string/bytes/reader via src, then we can just make the example write the sample source to disk first.

[gopherbot]

CL https://golang.org/cl/39236 mentions this issue.