range-val-address: fix false positive

[bernhardreisenberger]

This PR fixes the false positive detected by archseer. i added a few more tests too.

Closes #553

[archseer]

Thanks for the quick fix! This looks good to me.

[chavacava]

Hi @bernhardreisenberger, thanks for the bug fix (and sorry for the late response)

Testing the fix against Kubernetes code base (kubernetes/vendor/...) raised a nil pointer dereference:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x6bbcd2]

goroutine 2022 [running]:
github.com/mgechev/revive/rule.rangeValAddress.Visit(0xc009fe3400, 0xc00a2ff1d0, 0x7d1f60, 0xc009fc5db0, 0x7ceec0, 0xc00b8fd510)
	/workspaces/revive/rule/range-val-address.go:56 +0x72

https://github.com/bernhardreisenberger/revive/blob/4f55759aa2d003b1efc1c58623ed2fd0f616bbb3/rule/range-val-address.go#L53-L56

	t := w.file.Pkg.TypeOf(value)

	ast.Walk(rangeBodyVisitor{
		valueIsStarExpr: strings.HasPrefix(t.String(), "*"),

It seems that t is nil in some cases thus t.String() fails. The origin of this problem might be that file.Pkg.TypeCheck() is returning an error but we do not check for it.

nit: the README.md need to be updated to indicate that the rule is typed

[bernhardreisenberger]

Hi @chavacava

README.md is updated, and nil pointer dereference is fixed. should work fine now.

[chavacava]

Thanks @bernhardreisenberger!