From 28d61f4dfab52f4687236234039a217e612be9f7 Mon Sep 17 00:00:00 2001
From: kbkpbot <kbkpbot@sina.com>
Date: Sat, 28 Feb 2026 09:18:49 +0800
Subject: [PATCH] checker:fix compiler panic on wrong arg count with or block
 (#26665)

---
 vlib/v/checker/fn.v                              | 15 ++++++++++++---
 .../tests/method_call_on_undefined_err.out       |  7 -------
 .../wrong_arg_count_with_or_block_no_panic.out   | 16 ++++++++++++++++
 .../wrong_arg_count_with_or_block_no_panic.vv    | 15 +++++++++++++++
 4 files changed, 43 insertions(+), 10 deletions(-)
 create mode 100644 vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.out
 create mode 100644 vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index b1338fc25..616295460 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -1517,7 +1517,10 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 				}
 			}
 		}
-		c.check_expected_arg_count(mut node, func) or { return func.return_type }
+		c.check_expected_arg_count(mut node, func) or {
+			node.return_type = func.return_type
+			return func.return_type
+		}
 	}
 	// println / eprintln / panic can print anything
 	if args_len > 0 && fn_name in print_everything_fns {
@@ -2358,7 +2361,10 @@ fn (mut c Checker) method_call(mut node ast.CallExpr, mut continue_check &bool)
 				node.is_field = true
 				info := field_sym.info as ast.FnType
 
-				c.check_expected_arg_count(mut node, info.func) or { return info.func.return_type }
+				c.check_expected_arg_count(mut node, info.func) or {
+					node.return_type = info.func.return_type
+					return info.func.return_type
+				}
 				node.return_type = info.func.return_type
 				mut earg_types := []ast.Type{}
 
@@ -2546,7 +2552,10 @@ fn (mut c Checker) method_call(mut node ast.CallExpr, mut continue_check &bool)
 		&& method.ctdefine_idx != ast.invalid_type_idx {
 		node.should_be_skipped = c.evaluate_once_comptime_if_attribute(mut method.attrs[method.ctdefine_idx])
 	}
-	c.check_expected_arg_count(mut node, method) or { return method.return_type }
+	c.check_expected_arg_count(mut node, method) or {
+		node.return_type = method.return_type
+		return method.return_type
+	}
 	mut exp_arg_typ := ast.no_type // type of 1st arg for special builtin methods
 	mut param_is_mut := false
 	mut no_type_promotion := false
diff --git a/vlib/v/checker/tests/method_call_on_undefined_err.out b/vlib/v/checker/tests/method_call_on_undefined_err.out
index 6b8f5d36d..27e132e4b 100644
--- a/vlib/v/checker/tests/method_call_on_undefined_err.out
+++ b/vlib/v/checker/tests/method_call_on_undefined_err.out
@@ -56,10 +56,3 @@ vlib/v/checker/tests/method_call_on_undefined_err.vv:14:13: error: expected 0 ar
    16 |         exit(1)
 Details: have (string)
          want ()
-vlib/v/checker/tests/method_call_on_undefined_err.vv:14:31: error: unexpected `or` block, the function `foo` does not return an Option or a Result
-   12 | 
-   13 | fn main() {
-   14 |     res := foo('fe80::1234%ne0') or {
-      |                                  ~~~~
-   15 |         eprintln(err)
-   16 |         exit(1)
diff --git a/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.out b/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.out
new file mode 100644
index 000000000..b1078aa54
--- /dev/null
+++ b/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.out
@@ -0,0 +1,16 @@
+vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv:9:6: notice: condition is always true
+    7 |     // Test case: function with no params, called with extra args and or block with if-else
+    8 |     foo(1, 2, 3) or {
+    9 |         if true {
+      |            ~~~~
+   10 |             println('error')
+   11 |         } else {
+vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv:8:6: error: expected 0 arguments, but got 3
+    6 | fn main() {
+    7 |     // Test case: function with no params, called with extra args and or block with if-else
+    8 |     foo(1, 2, 3) or {
+      |         ~~~~~~~
+    9 |         if true {
+   10 |             println('error')
+Details: have (int literal, int literal, int literal)
+         want ()
diff --git a/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv b/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv
new file mode 100644
index 000000000..9c60e4b00
--- /dev/null
+++ b/vlib/v/checker/tests/wrong_arg_count_with_or_block_no_panic.vv
@@ -0,0 +1,15 @@
+// Test that wrong argument count with or block containing if-else
+// does not cause compiler panic (issue #26647)
+fn foo() ! {
+}
+
+fn main() {
+	// Test case: function with no params, called with extra args and or block with if-else
+	foo(1, 2, 3) or {
+		if true {
+			println('error')
+		} else {
+			println('other')
+		}
+	}
+}
-- 
2.39.5