Add support for else-if/else chains

testdata/src/default_config/else_if.go

@@ -0,0 +1,20 @@
+func fn() {
+	if true { // want "block should not start with a whitespace"
+
+		fmt.Println("a")
+	}
+
+	if true {
+		fmt.Println("a")
+	} else if false { // want "block should not start with a whitespace"
+
+		fmt.Println("b")
+	} else { // want "block should not start with a whitespace"
+
+		fmt.Println("c")
+		fmt.Println("c")
+		fmt.Println("c")
+		return // want "return statements should not be cuddled if block has more than two lines"
+
+	} // want "block should not end with a whitespace"
+}

testdata/src/default_config/else_if.go.golden

@@ -0,0 +1,16 @@
+func fn() {
+	if true { // want "block should not start with a whitespace"
+		fmt.Println("a")
+	}
+
+	if true {
+		fmt.Println("a")
+	} else if false { // want "block should not start with a whitespace"
+		fmt.Println("b")
+	} else { // want "block should not start with a whitespace"
+		fmt.Println("c")
+		fmt.Println("c")
+		fmt.Println("c")
+		return // want "return statements should not be cuddled if block has more than two lines"
+	} // want "block should not end with a whitespace"
+}

wsl.go

@@ -766,7 +766,14 @@ func (p *processor) firstBodyStatement(i int, allStmt []ast.Stmt) ast.Node {
 			}
 		}
 
-		p.parseBlockBody(nil, statementBodyContent)
+		// If statement bodies will be parsed already when finding block bodies.
+		// The reason is because if/else-if/else chains is nested in the AST
+		// where the else bit is a part of the if statement. Since if statements
+		// is the only statement that can be chained like this we exclude it
+		// from parsing it again here.
+		if _, ok := stmt.(*ast.IfStmt); !ok {
+			p.parseBlockBody(nil, statementBodyContent)
+		}
 	case []ast.Stmt:
 		// The Body field for an *ast.CaseClause or *ast.CommClause is of type
 		// []ast.Stmt. We must check leading and trailing whitespaces and then
@@ -946,6 +953,8 @@ func (p *processor) findBlockStmt(node ast.Node) []*ast.BlockStmt {
 	var blocks []*ast.BlockStmt
 
 	switch t := node.(type) {
+	case *ast.BlockStmt:
+		return []*ast.BlockStmt{t}
 	case *ast.AssignStmt:
 		for _, x := range t.Rhs {
 			blocks = append(blocks, p.findBlockStmt(x)...)
@@ -968,6 +977,8 @@ func (p *processor) findBlockStmt(node ast.Node) []*ast.BlockStmt {
 		blocks = append(blocks, p.findBlockStmt(t.Call)...)
 	case *ast.GoStmt:
 		blocks = append(blocks, p.findBlockStmt(t.Call)...)
+	case *ast.IfStmt:
+		blocks = append([]*ast.BlockStmt{t.Body}, p.findBlockStmt(t.Else)...)
 	}
 
 	return blocks