nakedret

nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.

Installation

go get -u github.com/alexkohler/nakedret

Usage

Similar to other Go static anaylsis tools (such as golint, go vet) , nakedret can be invoked with one or more filenames, directories, or packages named by its import path. Nakedret also supports the ... wildcard.

nakedret [flags] files/directories/packages

Currently, the only flag supported is -l, which is an optional numeric flag to specify the maximum length a function can be (in terms of line length). If not specified, it defaults to 5.

Purpose

As noted in Go's Code Review comments:

Naked returns are okay if the function is a handful of lines. Once it's a medium sized function, be explicit with your return values. Corollary: it's not worth it to name result parameters just because it enables you to use naked returns. Clarity of docs is always more important than saving a line or two in your function.

This tool aims to catch naked returns on non-trivial functions.

Example

Let's take the types package in the Go source as an example:

$ nakedret -l 25 types/
types/check.go:245 checkFiles naked returns on 26 line function 
types/typexpr.go:443 collectParams naked returns on 53 line function 
types/stmt.go:275 caseTypes naked returns on 27 line function 
types/lookup.go:275 MissingMethod naked returns on 39 line function

Below is one of the not so intuitive uses of naked returns in types/lookup.go found by nakedret (nakedret will return the line number of the last naked return in the function):

func MissingMethod(V Type, T *Interface, static bool) (method *Func, wrongType bool) {
	// fast path for common case
	if T.Empty() {
		return
	}

	// TODO(gri) Consider using method sets here. Might be more efficient.

	if ityp, _ := V.Underlying().(*Interface); ityp != nil {
		// TODO(gri) allMethods is sorted - can do this more efficiently
		for _, m := range T.allMethods {
			_, obj := lookupMethod(ityp.allMethods, m.pkg, m.name)
			switch {
			case obj == nil:
				if static {
					return m, false
				}
			case !Identical(obj.Type(), m.typ):
				return m, true
			}
		}
		return
	}

	// A concrete type implements T if it implements all methods of T.
	for _, m := range T.allMethods {
		obj, _, _ := lookupFieldOrMethod(V, false, m.pkg, m.name)

		f, _ := obj.(*Func)
		if f == nil {
			return m, false
		}

		if !Identical(f.typ, m.typ) {
			return m, true
		}
	}

	return
}

TODO

• Unit tests (may require some refactoring to do correctly)
• supporting toggling of build.Context.UseAllFiles may be useful for some.
• Configuration on whether or not to run on test files
• Vim quickfix format?

Contributing

Pull requests welcome!

Other static analysis tools

If you've enjoyed nakedret, take a look at my other static anaylsis tools!

• unimport - Finds unnecessary import aliases
• prealloc - Finds slice declarations that could potentially be preallocated.