all: if-is smartcast part 1 (#5730)

vlib/v/ast/ast.v

@@ -425,10 +425,10 @@ pub mut:
 pub struct IfExpr {
 pub:
 	tok_kind token.Kind
-	branches []IfBranch
 	left     Expr // `a` in `a := if ...`
 	pos      token.Position
 pub mut:
+	branches []IfBranch
 	is_expr  bool
 	typ      table.Type
 	has_else bool
@@ -439,7 +439,10 @@ pub:
 	cond     Expr
 	stmts    []Stmt
 	pos      token.Position
+	body_pos token.Position
 	comments []Comment
+pub mut:
+	smartcast bool // should only be true if cond is `x is sumtype`, it will be set in checker - if_expr
 }
 
 pub struct LockExpr {

vlib/v/ast/str.v

@@ -286,7 +286,7 @@ pub fn (node Stmt) str() string {
 					}
 				}
 				out += left.str()
-				if i < it.left.len - 1 {
+				if i < node.left.len - 1 {
 					out += ','
 				}
 			}