cmd/vet: mismatch between Printf checks and actual behaviour

[dominikh]

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

go version go1.11 linux/amd64

What did you do?

• go run https://play.golang.org/p/5rBLFTsNpqZ
• go vet https://play.golang.org/p/5rBLFTsNpqZ
• compare outputs

What did you expect to see?

Vet to accept the first Printf call and to flag the second one

What did you see instead?

Vet flags the first call and accepts the second one

[dominikh]

/cc @mvdan

[dominikh]

Another false negative:

var x struct{ A *int }
fmt.Printf("%p\n", x)

[dominikh]

One more false negative:

var x [2]int
fmt.Printf("%p", x)

[dominikh]

Another false positive, presumably because the check is confused by the Error method it can't call. fmt.Printf is fine with that though, as long as the concrete type is a string. https://play.golang.org/p/qAs0Ye8atHL

[mvdan]

Thanks for the ping - I might have a look at this during the current cycle.

[gopherbot]

Change https://golang.org/cl/147758 mentions this issue: cmd/vet: fix some pointer false positives in printf

[mvdan]

I've filed an issue about the second case in the original comment, as I think vet is technically doing what fmt documents.

[gopherbot]

Change https://golang.org/cl/147997 mentions this issue: cmd/vet: fix printf false negative with nested pointers