Empty structs aren't decoded correctly in function arguments.

[dallbee]

This is a pretty minor thing, but it confused me enough to make me want to fix it, unless its a harder problem than I'm realizing.

Empty structs are decoded as ..., `` or sometimes as unknown.

I'd be happy to take a stab at this tonight if this is indeed a bug.

Examples:

//go:noinline
func Foo(x struct{}) {
	panic("test")
}

func TestFoo(t *testing.T) {
	Foo(struct{}{})
}

Results in:

1: running [Created by testing.(*T).Run @ testing.go:1238]
 testing testing.go:1143 tRunner.func1.2(*T(#1), func(#2))
 testing testing.go:1146 tRunner.func1(*T(#3))
 panic.go:965 panic(interface{}(#1))
 pp ppl_test.go:16 Foo()
 pp pp_test.go:20 TestFoo(*T(#3))
 testing testing.go:1193 tRunner(*T(#3), func(0x8952b8))
exit status 2

And

//go:noinline
func Foo(x chan struct{}) {
	panic("test")
}

func TestFoo(t *testing.T) {
	Foo(nil)
}

Results in:

1: running [Created by testing.(*T).Run @ testing.go:1238]
 testing testing.go:1143 tRunner.func1.2(*T(#1), func(#2))
 testing testing.go:1146 tRunner.func1(*T(#3))
 panic.go:965 panic(interface{}(#1))
 pp ppl_test.go:16 Foo(chan <unknown>(0x0))
 pp pp_test.go:20 TestFoo(*T(#3))
 testing testing.go:1193 tRunner(*T(#3), func(0x8952b8))
exit status 2

[maruel]

I added them to cmd/panic/main.go and the output is so-so from the stdlib. May want to investigate later. I need to fix the CI first though before starting to fix this.

[maruel]

CI is fixed. Just need someone to help here.