From 5c3742fbd2c25988b4ea36641d10612835c67842 Mon Sep 17 00:00:00 2001
From: Kris Cherven <50562493+krischerven@users.noreply.github.com>
Date: Tue, 21 Apr 2020 21:48:51 -0400
Subject: [PATCH]  parser: check var names in for loops

---
 vlib/v/parser/for.v | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/vlib/v/parser/for.v b/vlib/v/parser/for.v
index 8b8621463f..fa1545d53c 100644
--- a/vlib/v/parser/for.v
+++ b/vlib/v/parser/for.v
@@ -73,12 +73,23 @@ fn (var p Parser) for_stmt() ast.Stmt {
 			p.check(.comma)
 			key_var_name = val_var_name
 			val_var_name = p.check_name()
+			if p.scope.known_var(key_var_name) {
+				p.error('redefinition of `$key_var_name`')
+			}
+			if p.scope.known_var(val_var_name) {
+				p.error('redefinition of `$val_var_name`')
+			}
 			p.scope.register(key_var_name, ast.Var{
 				name: key_var_name
 				typ: table.int_type
 			})
+		} else if p.scope.known_var(val_var_name) {
+			p.error('redefinition of `$val_var_name`')
 		}
 		p.check(.key_in)
+		if p.tok.kind == .name && p.tok.lit in [key_var_name, val_var_name] {
+			p.error('redefinition of `$p.tok.lit`')
+		}
 		// arr_expr
 		cond := p.expr(0)
 		// 0 .. 10