From 43e96ce5bb74a45d97d1de5265975be1127c3fcf Mon Sep 17 00:00:00 2001
From: Swastik Baranwal <swstkbaranwal@gmail.com>
Date: Mon, 26 Feb 2024 02:09:56 +0530
Subject: [PATCH]  parser: disallow defining map key more than once  (#20905)

---
 vlib/v/parser/parse_type.v                | 6 ++++++
 vlib/v/parser/tests/map_key_twice_err.out | 4 ++++
 vlib/v/parser/tests/map_key_twice_err.vv  | 2 ++
 3 files changed, 12 insertions(+)
 create mode 100644 vlib/v/parser/tests/map_key_twice_err.out
 create mode 100644 vlib/v/parser/tests/map_key_twice_err.vv

diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
index 839b30405..6d8285719 100644
--- a/vlib/v/parser/parse_type.v
+++ b/vlib/v/parser/parse_type.v
@@ -140,6 +140,12 @@ fn (mut p Parser) parse_map_type() ast.Type {
 		return 0
 	}
 	p.check(.rsbr)
+	if p.tok.kind == .lsbr {
+		if p.peek_tok.kind !in [.rsbr, .number] {
+			p.error_with_pos('maps can only have a single key', p.peek_tok.pos())
+			return 0
+		}
+	}
 	value_type := p.parse_type()
 	if value_type.idx() == 0 {
 		// error is reported in parse_type
diff --git a/vlib/v/parser/tests/map_key_twice_err.out b/vlib/v/parser/tests/map_key_twice_err.out
new file mode 100644
index 000000000..05bd066de
--- /dev/null
+++ b/vlib/v/parser/tests/map_key_twice_err.out
@@ -0,0 +1,4 @@
+vlib/v/parser/tests/map_key_twice_err.vv:1:14: error: maps can only have a single key
+    1 | _ := map[u8][u8]{}
+      |              ~~
+    2 |
diff --git a/vlib/v/parser/tests/map_key_twice_err.vv b/vlib/v/parser/tests/map_key_twice_err.vv
new file mode 100644
index 000000000..df6a93784
--- /dev/null
+++ b/vlib/v/parser/tests/map_key_twice_err.vv
@@ -0,0 +1,2 @@
+_ := map[u8][u8]{}
+
-- 
2.39.5