all: implement `if foo in [Foo1, Foo2, Foo3]` (#11486)

vlib/v/checker/checker.v

@@ -1356,11 +1356,12 @@ pub fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 		.key_in, .not_in {
 			match right_final.kind {
 				.array {
-					elem_type := right_final.array_info().elem_type
-					// if left_default.kind != right_sym.kind {
-					c.check_expected(left_type, elem_type) or {
-						c.error('left operand to `$node.op` does not match the array element type: $err.msg',
-							left_right_pos)
+					if left_sym.kind !in [.sum_type, .interface_] {
+						elem_type := right_final.array_info().elem_type
+						c.check_expected(left_type, elem_type) or {
+							c.error('left operand to `$node.op` does not match the array element type: $err.msg',
+								left_right_pos)
+						}
 					}
 				}
 				.map {
@@ -4522,8 +4523,10 @@ pub fn (mut c Checker) array_init(mut node ast.ArrayInit) ast.Type {
 				c.expected_type = elem_type
 				continue
 			}
-			c.check_expected(typ, elem_type) or {
-				c.error('invalid array element: $err.msg', expr.position())
+			if expr !is ast.TypeNode {
+				c.check_expected(typ, elem_type) or {
+					c.error('invalid array element: $err.msg', expr.position())
+				}
 			}
 		}
 		if node.is_fixed {

vlib/v/gen/c/infix_expr.v

@@ -313,6 +313,15 @@ fn (mut g Gen) infix_expr_cmp_op(node ast.InfixExpr) {
 	}
 }
 
+fn (mut g Gen) infix_expr_in_sumtype_interface_array(infix_exprs []ast.InfixExpr) {
+	for i in 0 .. infix_exprs.len {
+		g.infix_expr_is_op(infix_exprs[i])
+		if i != infix_exprs.len - 1 {
+			g.write(' || ')
+		}
+	}
+}
+
 // infix_expr_in_op generates code for `in` and `!in`
 fn (mut g Gen) infix_expr_in_op(node ast.InfixExpr) {
 	left := g.unwrap(node.left_type)
@@ -321,6 +330,26 @@ fn (mut g Gen) infix_expr_in_op(node ast.InfixExpr) {
 		g.write('!')
 	}
 	if right.unaliased_sym.kind == .array {
+		if left.sym.kind in [.sum_type, .interface_] {
+			if mut node.right is ast.ArrayInit {
+				if node.right.exprs.len > 0 {
+					mut infix_exprs := []ast.InfixExpr{}
+					for i in 0 .. node.right.exprs.len {
+						infix_exprs << ast.InfixExpr{
+							op: .key_is
+							left: node.left
+							left_type: node.left_type
+							right: node.right.exprs[i]
+							right_type: node.right.expr_types[i]
+						}
+					}
+					g.write('(')
+					g.infix_expr_in_sumtype_interface_array(infix_exprs)
+					g.write(')')
+					return
+				}
+			}
+		}
 		if mut node.right is ast.ArrayInit {
 			if node.right.exprs.len > 0 {
 				// `a in [1,2,3]` optimization => `a == 1 || a == 2 || a == 3`

vlib/v/parser/expr.v

@@ -472,7 +472,15 @@ fn (mut p Parser) infix_expr(left ast.Expr) ast.Expr {
 	if op in [.key_is, .not_is] {
 		p.expecting_type = true
 	}
+	is_key_in := op in [.key_in, .not_in]
+	if is_key_in {
+		p.inside_in_array = true
+	}
 	right = p.expr(precedence)
+	if is_key_in {
+		p.inside_in_array = false
+	}
+
 	p.expecting_type = prev_expecting_type
 	if p.pref.is_vet && op in [.key_in, .not_in] && right is ast.ArrayInit
 		&& (right as ast.ArrayInit).exprs.len == 1 {

vlib/v/parser/parser.v

@@ -44,6 +44,7 @@ mut:
 	inside_unsafe_fn    bool
 	inside_str_interp   bool
 	inside_array_lit    bool
+	inside_in_array     bool
 	or_is_handled       bool       // ignore `or` in this expression
 	builtin_mod         bool       // are we in the `builtin` module?
 	mod                 string     // current module name
@@ -2233,6 +2234,18 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 		// JS. function call with more than 1 dot
 		node = p.call_expr(language, mod)
 	} else {
+		if p.inside_in_array && ((lit0_is_capital && !known_var && language == .v)
+			|| (p.peek_tok.kind == .dot && p.peek_token(2).lit.len > 0
+			&& p.peek_token(2).lit[0].is_capital())
+			|| p.table.find_type_idx(p.mod + '.' + p.tok.lit) > 0) {
+			type_pos := p.tok.position()
+			typ := p.parse_type()
+			return ast.TypeNode{
+				typ: typ
+				pos: type_pos
+			}
+		}
+
 		ident := p.parse_ident(language)
 		node = ident
 		if p.inside_defer {

vlib/v/tests/in_expression_test.v

@@ -264,3 +264,20 @@ fn test_in_expression_numeric() {
 	assert 1.0625 in f2
 	assert 3.5 !in f2
 }
+
+struct Foo1 {}
+
+struct Foo2 {}
+
+struct Foo3 {}
+
+type Foo = Foo1 | Foo2 | Foo3
+
+fn test_in_sumtype_array() {
+	foo := Foo(Foo3{})
+
+	if foo in [Foo1, Foo3] {
+		println(foo)
+		assert true
+	}
+}