gccgo: does not error on unused var

[Dmitry Vyukov]

gccgo successfully compiles the following incorrect program:

package a
func g() {
    var f = func() {}
}

Both gc and gotype say:

test.go:3:6: f declared but not used

gofrontend is on commit 81810917af7ba19e1f9f8efc8b1989f7d6419d30

[Dmitry Vyukov]

@ianlancetaylor

[Caleb Spare]

That program is not incorrect. From the spec:

Implementation restriction: A compiler may make it illegal to declare a variable inside a function body if the variable is never used.

So gccgo is free to allow the unused var.

I'm not sure whether gccgo disallows other unused vars, though (don't have a gccgo installation available right now).

[Chris Manghane]

This is a gccgo bug; it doesn't check if variables initialized by a function literal are ever used. I don't think this is on purpose, despite the disclaimer in the specification.

[GopherBot]

CL https://golang.org/cl/13908 mentions this issue.