From b853aa74b008eb2e90d19e86c42d08dfede762df Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Tue, 21 Apr 2026 05:40:52 +0300
Subject: [PATCH] checker: fix ?&t cannot be compared to nil in comptime
 indirections branch (fixes #26893)

---
 vlib/v/checker/containers.v                   |  2 +-
 vlib/v/checker/infix.v                        | 22 ++++++++++---
 ..._generic_method_ret_ptr_none_assert_test.v | 33 +++++++++++++++++++
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/vlib/v/checker/containers.v b/vlib/v/checker/containers.v
index 7599be33b..562b52216 100644
--- a/vlib/v/checker/containers.v
+++ b/vlib/v/checker/containers.v
@@ -1082,7 +1082,7 @@ fn (mut c Checker) check_append(mut node ast.InfixExpr, left_type ast.Type, righ
 	mut right_sym := c.table.sym(right_type)
 	mut left_sym := c.table.sym(left_type)
 	if left_type.has_flag(.option) && node.left is ast.Ident && node.left.or_expr.kind == .absent {
-		c.check_option_infix_expr(node, left_type, right_type, left_sym, right_sym)
+		c.check_option_infix_expr(mut node, left_type, right_type, left_sym, right_sym)
 	}
 	right_pos := node.right.pos()
 	// `array << elm`
diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index d9b6441e2..45597e9ad 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -368,7 +368,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 				}
 			}
 
-			c.check_option_infix_expr(node, left_type, right_type, left_sym, right_sym)
+			c.check_option_infix_expr(mut node, left_type, right_type, left_sym, right_sym)
 
 			// In SQL, `field == nil`/`field != nil` is lowered to NULL comparisons.
 			if !c.inside_sql {
@@ -802,7 +802,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 					}
 				}
 			} else {
-				c.check_option_infix_expr(node, left_type, right_type, left_sym, right_sym)
+				c.check_option_infix_expr(mut node, left_type, right_type, left_sym, right_sym)
 			}
 			if node.left.is_nil() || node.right.is_nil() {
 				c.error('cannot use `${node.op.str()}` with `nil`', node.pos)
@@ -1085,7 +1085,7 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 	// TODO: move this to symmetric_check? Right now it would break `return 0` for `fn()?int `
 	if node.left !in [ast.Ident, ast.IndexExpr, ast.SelectorExpr, ast.ComptimeSelector]
 		|| node.op in [.eq, .ne] {
-		c.check_option_infix_expr(node, left_type, right_type, left_sym, right_sym)
+		c.check_option_infix_expr(mut node, left_type, right_type, left_sym, right_sym)
 	}
 
 	left_is_result := left_type.has_flag(.result)
@@ -1417,7 +1417,15 @@ fn (mut c Checker) check_sort_external_variable_access(node ast.Expr) bool {
 	return true
 }
 
-fn (mut c Checker) check_option_infix_expr(node ast.InfixExpr, left_type ast.Type, right_type ast.Type, left_sym ast.TypeSymbol, right_sym ast.TypeSymbol) {
+fn (c &Checker) option_payload_can_compare_to_nil(typ ast.Type, sym ast.TypeSymbol) bool {
+	mut option_type := typ
+	if sym.kind == .alias && sym.info is ast.Alias && sym.info.parent_type.has_flag(.option) {
+		option_type = sym.info.parent_type
+	}
+	return option_type.clear_option_and_result().is_any_kind_of_pointer()
+}
+
+fn (mut c Checker) check_option_infix_expr(mut node ast.InfixExpr, left_type ast.Type, right_type ast.Type, left_sym ast.TypeSymbol, right_sym ast.TypeSymbol) {
 	// SQL expressions can compare optional values directly, but anon fn bodies in SQL
 	// should keep regular option checks.
 	if c.inside_sql && !c.inside_anon_fn {
@@ -1427,6 +1435,12 @@ fn (mut c Checker) check_option_infix_expr(node ast.InfixExpr, left_type ast.Typ
 		|| (left_sym.kind == .alias && (left_sym.info as ast.Alias).parent_type.has_flag(.option))
 	right_is_option := right_type.has_flag(.option)
 		|| (right_sym.kind == .alias && (right_sym.info as ast.Alias).parent_type.has_flag(.option))
+	if left_is_option && node.right.is_nil()
+		&& c.option_payload_can_compare_to_nil(left_type, left_sym) {
+		node.right = ast.None{}
+		node.right_type = ast.none_type
+		return
+	}
 	if (node.left is ast.None && right_is_option)
 		|| (node.right is ast.None && left_is_option)
 		|| (left_sym.kind == .none || right_sym.kind == .none) {
diff --git a/vlib/v/tests/options/option_generic_method_ret_ptr_none_assert_test.v b/vlib/v/tests/options/option_generic_method_ret_ptr_none_assert_test.v
index 770e6dcfd..03d8ab3e6 100644
--- a/vlib/v/tests/options/option_generic_method_ret_ptr_none_assert_test.v
+++ b/vlib/v/tests/options/option_generic_method_ret_ptr_none_assert_test.v
@@ -112,3 +112,36 @@ fn test_generic_method_returning_option_reference_preserves_many_values() {
 	}
 	assert list.size == 0
 }
+
+struct Tag {
+	id     string
+	parent ?&Tag
+}
+
+fn is_nil_field[T](val T) bool {
+	$if T.indirections != 0 {
+		return val == unsafe { nil }
+	}
+	return false
+}
+
+fn is_not_nil_field[T](val T) bool {
+	$if T.indirections != 0 {
+		return val != unsafe { nil }
+	}
+	return false
+}
+
+fn test_option_pointer_can_compare_to_nil_in_comptime_indirection_branch() {
+	orphan := Tag{}
+	child := &Tag{
+		id: 'child'
+	}
+	parent := Tag{
+		parent: child
+	}
+	assert !is_nil_field(orphan.id)
+	assert is_nil_field(orphan.parent)
+	assert !is_nil_field(parent.parent)
+	assert is_not_nil_field(parent.parent)
+}
-- 
2.39.5