cmd/compile: incorrect column reported for invalid struct field names

[dhowden]

Please answer these questions before submitting your issue. Thanks!

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

go1.10

Does this issue reproduce with the latest release?

Yes

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

GOARCH="amd64"
GOOS="darwin"

What did you do?

Tried to compile this (incorrect code):

package main

type Struct struct {}

func main() {
	x := Struct{
		InvalidName: 10,
	}
}

What did you expect to see?

prog.go:7:3: unknown field 'InvalidName' in struct literal of type Struct

	x := Struct{
		InvalidName: 10,
//		^
	}

What did you see instead?

prog.go:7:14: unknown field 'InvalidName' in struct literal of type Struct

	x := Struct{
		InvalidName: 10,
//		           ^
	}

Go Playground: https://play.golang.org/p/-UT1IgmXgQD

[mvdan]

This does not concern go/parser; rather, this is the compiler. The error comes from gc, and the position from syntax.

I also believe that this is working as intended, as the position of the key-value expression is the position of the colon token. There was an issue where @mdempsky suggested that, in the new syntax package, node positions shouldn't always be their start position. For example, in x + y, the position of the binary arithmetic expression should be the +. However, I can't seem to find that issue right now.

Having said that, I can understand that the error concerns the field name, not the entire key-value expression. Perhaps the error in this case should use the position for the field, and not the entire key-value expression.

Also cc @griesemer.

[mvdan]

Found the issue now; it's #16943.

[griesemer]

Package syntax provides all the relevant positions here. It's just a matter of using the right one. Will fix.

[gopherbot]

Change https://golang.org/cl/100457 mentions this issue: cmd/compile: use key position for key:val elements in composite literals