html/template: make FuncMap an alias for text/template.FuncMap

[rogpeppe]

As discussed on Twitter recently, when generics come around, the html/template and text/template APIs can reasonably be abstracted into a single generic interface, but the fact that FuncMap is defined as two separate types makes it a bit harder than it could be.

I propose that in html/template, FuncMap shall be defined as an alias as follows:

package template
import "text/template"

type FuncMap = template.FuncMap

As html/template already imports text/template, there's no problem with a change in the dependency graph, and I can't currently see any potential issues from combining the two types.

[mvdan]

Do you think any reasonable user programs could break because of this change? I can imagine some artificial cases, like requiring the two types to be different via e.g. reflection, but I don't imagine anyone would be doing that.

[rsc]

Seems reasonable to me. Adding to minutes. /cc @robpike

[rsc]

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

[robpike]

Seems sound.

[rogpeppe]

I can imagine some artificial cases, like requiring the two types to be different via e.g. reflection, but I don't imagine anyone would be doing that.

I thought about that, but I couldn't think of a realistic case where it might be a problem, Hyrum's Law notwithstanding.

[rsc]

Based on the discussion above, this proposal seems like a likely accept.
— rsc for the proposal review group

[rsc]

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group

[gopherbot]

Change https://go.dev/cl/389156 mentions this issue: html/template: make FuncMap a type alias of text/template.FuncMap