From 00b68174eef6ec19c8bf5e09ac92db91cb7e8d23 Mon Sep 17 00:00:00 2001
From: Hedgegod <werstak192@gmail.com>
Date: Sat, 14 Feb 2026 21:54:54 +0300
Subject: [PATCH] checker: avoid panic on unresolved infix operand types in
 -check (fixes #26458) (#26607)

---
 vlib/v/checker/infix.v                               | 12 ++++++++++++
 .../tests/infix_is_unknown_module_no_panic.out       |  7 +++++++
 .../tests/infix_is_unknown_module_no_panic.vv        | 12 ++++++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 vlib/v/checker/tests/infix_is_unknown_module_no_panic.out
 create mode 100644 vlib/v/checker/tests/infix_is_unknown_module_no_panic.vv

diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index 6e245312d..960967c53 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -9,6 +9,10 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 		c.expected_type = former_expected_type
 	}
 	mut left_type := c.expr(mut node.left)
+	if left_type == ast.no_type {
+		node.left_type = left_type
+		return ast.void_type
+	}
 	mut left_sym := c.table.sym(left_type)
 	node.left_type = left_type
 	c.expected_type = left_type
@@ -81,6 +85,14 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 		}
 	}
 	mut right_type := c.expr(mut node.right)
+	if right_type == ast.no_type {
+		node.right_type = right_type
+		if node.op in [.key_is, .not_is] {
+			node.promoted_type = ast.bool_type
+			return ast.bool_type
+		}
+		return ast.void_type
+	}
 	if node.op == .key_is {
 		c.inside_x_is_type = false
 	}
diff --git a/vlib/v/checker/tests/infix_is_unknown_module_no_panic.out b/vlib/v/checker/tests/infix_is_unknown_module_no_panic.out
new file mode 100644
index 000000000..4c3a8f655
--- /dev/null
+++ b/vlib/v/checker/tests/infix_is_unknown_module_no_panic.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/infix_is_unknown_module_no_panic.vv:7:13: error: unknown module `io`
+    5 | fn main() {
+    6 |     _ := sample() or {
+    7 |         if err is io.Eof {
+      |                   ~~
+    8 |             return
+    9 |         }
diff --git a/vlib/v/checker/tests/infix_is_unknown_module_no_panic.vv b/vlib/v/checker/tests/infix_is_unknown_module_no_panic.vv
new file mode 100644
index 000000000..3f4f30c7f
--- /dev/null
+++ b/vlib/v/checker/tests/infix_is_unknown_module_no_panic.vv
@@ -0,0 +1,12 @@
+fn sample() !int {
+	return error('x')
+}
+
+fn main() {
+	_ := sample() or {
+		if err is io.Eof {
+			return
+		}
+		return
+	}
+}
-- 
2.39.5