empty-block: ignore checking blocks of funcs and func literals (#17)

* Adds rule superfluous-else (an extension of indent-error-flow)

* Fix superfluous-else rule struct namming.

* Adds superfuous-else rule to the rules table

* Modifies empty-block rule to ignore bodies of
func literals and funcs

* add test cases on functions with a receiver for completeness

fixtures/empty-block.go

@@ -2,14 +2,19 @@
 
 package fixtures
 
-func f(x int) bool { // MATCH /this block is empty, you can remove it/
+func f(x int) bool {} // Must not match
 
-}
+type foo struct {}
+
+func (f foo) f(x *int) string {} // Must not match
+func (f *foo) g(y *int) string {} // Must not match
 
 func g(f func() bool) string {
 	{ // MATCH /this block is empty, you can remove it/
 	}
 
+	a := func(e error){} // Must not match
+
 	if ok := f(); ok { // MATCH /this block is empty, you can remove it/
 		// only a comment
 	} else {

rule/empty-block.go

@@ -17,7 +17,7 @@ func (r *EmptyBlockRule) Apply(file *lint.File, arguments lint.Arguments) []lint
 		failures = append(failures, failure)
 	}
 
-	w := lintEmptyBlock{make(map[*ast.IfStmt]bool), onFailure}
+	w := lintEmptyBlock{make([]*ast.BlockStmt, 0), onFailure}
 	ast.Walk(w, file.AST)
 	return failures
 }
@@ -28,16 +28,32 @@ func (r *EmptyBlockRule) Name() string {
 }
 
 type lintEmptyBlock struct {
-	ignore    map[*ast.IfStmt]bool
+	ignore    []*ast.BlockStmt
 	onFailure func(lint.Failure)
 }
 
 func (w lintEmptyBlock) Visit(node ast.Node) ast.Visitor {
+	fd, ok := node.(*ast.FuncDecl)
+	if ok {
+		w.ignore = append(w.ignore, fd.Body)
+		return w
+	}
+
+	fl, ok := node.(*ast.FuncLit)
+	if ok {
+		w.ignore = append(w.ignore, fl.Body)
+		return w
+	}
+
 	block, ok := node.(*ast.BlockStmt)
 	if !ok {
 		return w
 	}
 
+	if mustIgnore(block, w.ignore) {
+		return w
+	}
+
 	if len(block.List) == 0 {
 		w.onFailure(lint.Failure{
 			Confidence: 1,
@@ -50,3 +66,12 @@ func (w lintEmptyBlock) Visit(node ast.Node) ast.Visitor {
 
 	return w
 }
+
+func mustIgnore(block *ast.BlockStmt, blackList []*ast.BlockStmt) bool {
+	for _, b := range blackList {
+		if b == block {
+			return true
+		}
+	}
+	return false
+}