cmd/gofmt: incorrect indentation of comments for LabeledStmt

[dave]

Please answer these questions before submitting your issue. Thanks!

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

go1.11

Does this issue reproduce with the latest release?

Yes

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

darwin/amd64

What did you do?

If a LabeledStmt has an inline comment before and after the Colon, then an inline comment on the previous line will be indented incorrectly:

https://play.golang.org/p/mSDEYsc_34O

This code should not change with gofmt:

package main

func main() {

	/* comment */
L /* long comment */ : /* comment */
	print("foo")

	goto L

}

... however it changes to:

package main

func main() {

			/* comment */
L /* long comment */ : /* comment */
	print("foo")

	goto L

}

[agnivade]

Curious to know - did you encounter this in a real-world code ?

[dave]

No, not real-world code. I'm analysing all the positions that gofmt allows comments to be attached to the AST - see: https://github.com/dave/dst/blob/remove-doc-comment/gendst/postests/position-tests.go#L112-L115

[agnivade]

I see. gofmt's heuristics are tuned for real world code. I wonder whether we should tackle a corner case like this.

@griesemer

[dave]

Yup agreed - unlikely to come up in normal use, but it's the only formatting anomaly I've found yet, so I thought I'd mention it. I certainly wouldn't be too upset if this didn't get fixed.

[griesemer]

It shouldn't be too hard to break alignment before a label. Assigning to myself so it stays in my radar but unlikely to get addressed anytime soon. Not important.

Thanks for reporting this irregularity.