cmd/gofmt: inconsistent whitespace after map value type

[dsnet]

Consider the following:

var _ = map[string]func() bool{
	"Func": func() bool {
		return false
	},
}

On one line it's go fmt'd as func() bool{ and as func() bool { on the other line. Note the space between bool and {.

In the previous case, this is the syntax for a map literal, while the latter is a function declaration.

Perhaps we should always output a space after a type expression (e.g., func() bool or chan bool) that contains a space?

[mknyszek]

CC @griesemer

[mknyszek]

Is this new at tip or has this behavior been present in Go 1.18 and earlier?

[dsnet]

I believe this has been the behavior since forever.

Given that Go1.19 is going to cause lots of code churn anyways (due to godoc formatting). This might be the best time to fix all the little go fmt quirks.

[cespare]

Personally I like it better how it is now.

The change would increase consistency in a textual sense by making the two strings the same (func() bool {) but syntactically it's less consistent since how map (and slice, array, ...) literals are formatted depends on the spelling of the type.

With the way it is today, when one's eyes see the space (or not) it's an immediate clue about whether you're reading, for example, a map literal or a function literal. And that is a tiny boon to readability.