proposal: text/template: add {{break 2}} and {{continue 2}} support

[Drugoy]

Proposal Details

Issue #20531 introduced {{break}} and {{continue}} support, but they are currently limited to the innermost {{range}}.
I'd like to be able to {{break}} 2nd level {{range}} from inside an {{if ...}} block of an inner {{range}} block (to stop parsing a bigger list of objects when I've found what I was looking for).

[AlexanderYastrebov]

Currently a workaround is possible using a variable https://go.dev/play/p/Rt9WyUb-tsk:

{{ $done := false }}
{{ range .Lists }}
	{{ range $v := . }}
		{{ $v }}
		{{ if eq $v "bar" }}
			{{ $done = true }}
			{{ break }}
		{{ end }}
	{{ end }}
	{{ if $done }}
		{{ break }}
	{{ end }}
{{ end }}

[ianlancetaylor]

CC @robpike

[robpike]

The case arises rarely enough that the workaround seems fine. Templates do not have to support everything from other languages. Also, the numeric form of this (break 2) is famously error-prone. The right solution would involve adding statement labels, and that is a bridge too far.

[Drugoy]

Then 'no go' it is for this proposal.
Thank you.