/cc @mvdan

Another false negative:

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

One more false negative:

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

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

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

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

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

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

This false positive seems related:

$ cat main.go
package main

import (
	"fmt"
)

type foo struct {
	root *node
}

type node struct {
	value int
}

type foo2 struct {
	root int
}

func main() {
	var t foo
	fmt.Printf("t = %x\n", &t)

	var t2 foo2
	fmt.Printf("t2 = %x\n", &t2)
}
bug $ vet .
/Users/dgryski/go/src/github.com/dgryski/bug/main.go:21:2: Printf format %x has arg &t of wrong type *github.com/dgryski/bug.foo

It seems like vet doesn't know that %x happily prints pointers, but it seem to only know not that for foo, not foo2 which doesn't itself contain a pointer.

(If it's not related, I can open another bug)

I don't intend to work more on vet during this cycle, so I'm unassigning myself in case someone else wants to continue the work. Right now, only the two bugs in the original post are fixed; the other four aren't fixed yet, assuming they're not duplicates.

/cc @alandonovan

Related: fmt.Sprintf("%d", new(int)) prints a string of decimal digits, which appears in practice to be almost always a mistake caused by forgetting to dereference a pointer to an integer. In this case the vet check is consistent with the behavior of fmt, but arguably the vet check should be intentionally stricter than fmt (since we can't change fmt). See #62595.