From c6afba84ade4f27bf4ba448bac7b300bffbacd37 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 06:06:51 +0300
Subject: [PATCH] checker: fix wrong error when smartcasting references to
 sumtypes (fixes #17236)

---
 vlib/v/checker/infix.v                          | 10 ++++++++--
 vlib/v/gen/c/cgen.v                             |  2 +-
 vlib/v/gen/c/infix.v                            | 14 +++++++++++++-
 vlib/v/tests/conditions/ifs/if_smartcast_test.v | 17 +++++++++++++++++
 4 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index 09ddd2e15..4fc6907bc 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -883,8 +883,14 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 					&& !c.comptime.is_comptime(node.left) {
 					c.error('`${op}` can only be used with interfaces and sum types', node.pos) // can be used in sql too, but keep err simple
 				} else if mut left_sym.info is ast.SumType {
-					if typ !in left_sym.info.variants
-						&& c.unwrap_generic(typ) !in left_sym.info.variants {
+					variant_typ := if left_type.nr_muls() > 0
+						&& typ.nr_muls() <= left_type.nr_muls() {
+						typ.set_nr_muls(0)
+					} else {
+						typ
+					}
+					if variant_typ !in left_sym.info.variants
+						&& c.unwrap_generic(variant_typ) !in left_sym.info.variants {
 						c.error('`${left_sym.name}` has no variant `${typ_sym.name}`', right_pos)
 					}
 				} else if left_sym.info is ast.Interface {
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index f5991587b..0727e3f3e 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -7757,7 +7757,7 @@ fn (mut g Gen) ident(node ast.Ident) {
 									styp := g.base_type(resolved_var.typ)
 									g.write('*(${styp}*)')
 								}
-							} else if !g.arg_no_auto_deref {
+							} else if !g.arg_no_auto_deref && !typ.is_ptr() {
 								g.write('*')
 							}
 						} else if interface_var_needs_deref
diff --git a/vlib/v/gen/c/infix.v b/vlib/v/gen/c/infix.v
index 81b3bc41e..9bc2bbe3f 100644
--- a/vlib/v/gen/c/infix.v
+++ b/vlib/v/gen/c/infix.v
@@ -1093,6 +1093,11 @@ fn (mut g Gen) infix_expr_is_op(node ast.InfixExpr) {
 		node.left_type)))
 	is_aggregate := node.left is ast.Ident && g.comptime.get_ct_type_var(node.left) == .aggregate
 	right_sym := g.table.sym(node.right_type)
+	mut right_type := node.right_type
+	if (left_sym.kind == .sum_type || is_aggregate) && node.left_type.nr_muls() > 0
+		&& right_type.nr_muls() <= node.left_type.nr_muls() {
+		right_type = right_type.set_nr_muls(0)
+	}
 	if left_sym.kind == .interface && right_sym.kind == .interface {
 		g.gen_interface_is_op(node)
 		return
@@ -1139,7 +1144,14 @@ fn (mut g Gen) infix_expr_is_op(node ast.InfixExpr) {
 	} else if node.right is ast.Ident && node.right.name == g.comptime.comptime_for_variant_var {
 		variant_idx := g.type_resolver.get_ct_type_or_default('${g.comptime.comptime_for_variant_var}.typ',
 			ast.void_type)
-		g.write('${int(variant_idx)}')
+		if (left_sym.kind == .sum_type || is_aggregate) && node.left_type.nr_muls() > 0
+			&& variant_idx.nr_muls() <= node.left_type.nr_muls() {
+			g.write('${int(variant_idx.set_nr_muls(0))}')
+		} else {
+			g.write('${int(variant_idx)}')
+		}
+	} else if node.right is ast.TypeNode {
+		g.write('${int(right_type)}')
 	} else {
 		g.expr(node.right)
 	}
diff --git a/vlib/v/tests/conditions/ifs/if_smartcast_test.v b/vlib/v/tests/conditions/ifs/if_smartcast_test.v
index 62c4cdbd3..96113891c 100644
--- a/vlib/v/tests/conditions/ifs/if_smartcast_test.v
+++ b/vlib/v/tests/conditions/ifs/if_smartcast_test.v
@@ -325,3 +325,20 @@ fn test_nested_pointer_smartcast() {
 		}
 	}
 }
+
+struct RefVariantType {
+	value int
+}
+
+type RefSmartcastSum = RefVariantType | int
+
+fn test_reference_sumtype_variant_smartcast() {
+	sum_ref := &RefSmartcastSum(RefVariantType{
+		value: 7
+	})
+	if sum_ref is &RefVariantType {
+		assert sum_ref.value == 7
+	} else {
+		assert false
+	}
+}
-- 
2.39.5