From fab65047d3bced165c79cea5fa49828ccefced1b Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 05:02:13 +0300
Subject: [PATCH] parser: fix inaccurate error message in match expressions
 (fixes #13669)

---
 vlib/v/parser/expr.v                                | 8 +++++++-
 vlib/v/parser/tests/match_invalid_case_expr_err.out | 7 +++++++
 vlib/v/parser/tests/match_invalid_case_expr_err.vv  | 9 +++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/parser/tests/match_invalid_case_expr_err.out
 create mode 100644 vlib/v/parser/tests/match_invalid_case_expr_err.vv

diff --git a/vlib/v/parser/expr.v b/vlib/v/parser/expr.v
index ae067b639..b2c200a35 100644
--- a/vlib/v/parser/expr.v
+++ b/vlib/v/parser/expr.v
@@ -891,7 +891,13 @@ fn (mut p Parser) infix_expr(left ast.Expr) ast.Expr {
 	if op in [.decl_assign, .assign] {
 		p.inside_assign_rhs = true
 	}
-	right = p.expr(if op == .power { precedence - 1 } else { precedence })
+	if p.inside_match_case && p.tok.kind == .lcbr {
+		// In a match branch, a bare `{` opens the branch body; it is not the rhs of
+		// the infix operator.
+		p.unexpected(prepend_msg: 'invalid expression:')
+	} else {
+		right = p.expr(if op == .power { precedence - 1 } else { precedence })
+	}
 	p.inside_assign_rhs = old_assign_rhs
 	if op in [.plus, .minus, .mul, .power, .div, .mod, .lt, .eq] && mut right is ast.PrefixExpr {
 		mut right_expr := right.right
diff --git a/vlib/v/parser/tests/match_invalid_case_expr_err.out b/vlib/v/parser/tests/match_invalid_case_expr_err.out
new file mode 100644
index 000000000..518953da1
--- /dev/null
+++ b/vlib/v/parser/tests/match_invalid_case_expr_err.out
@@ -0,0 +1,7 @@
+vlib/v/parser/tests/match_invalid_case_expr_err.vv:4:8: error: invalid expression: unexpected token `{`
+    2 |     x := 1
+    3 |     match true {
+    4 |         x >  {
+      |              ^
+    5 |             y := 0
+    6 |         }
diff --git a/vlib/v/parser/tests/match_invalid_case_expr_err.vv b/vlib/v/parser/tests/match_invalid_case_expr_err.vv
new file mode 100644
index 000000000..434882115
--- /dev/null
+++ b/vlib/v/parser/tests/match_invalid_case_expr_err.vv
@@ -0,0 +1,9 @@
+fn test_match_invalid_case_expr() {
+	x := 1
+	match true {
+		x >  {
+			y := 0
+		}
+		else {}
+	}
+}
-- 
2.39.5