allow `lock` expression to return multiple objects (#8657)

vlib/v/checker/checker.v

@@ -2551,7 +2551,8 @@ pub fn (mut c Checker) assign_stmt(mut assign_stmt ast.AssignStmt) {
 	mut right_len := assign_stmt.right.len
 	mut right_type0 := table.void_type
 	for right in assign_stmt.right {
-		if right is ast.CallExpr || right is ast.IfExpr || right is ast.MatchExpr {
+		if right is ast.CallExpr || right is ast.IfExpr || right is ast.LockExpr
+			|| right is ast.MatchExpr {
 			right_type0 = c.expr(right)
 			assign_stmt.right_types = [
 				c.check_expr_opt_call(right, right_type0),

vlib/v/gen/c/cgen.v

@@ -1742,6 +1742,7 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 	right_expr := assign_stmt.right[0]
 	match right_expr {
 		ast.CallExpr { return_type = right_expr.return_type }
+		ast.LockExpr { return_type = right_expr.typ }
 		ast.MatchExpr { return_type = right_expr.return_type }
 		ast.IfExpr { return_type = right_expr.typ }
 		else {}

vlib/v/tests/shared_lock_expr_test.v

@@ -12,3 +12,32 @@ fn test_lock_expr() {
 	assert m == -57
 	assert n == 173
 }
+
+struct Abc {
+mut:
+	a f64
+}
+
+fn test_multi_objects() {
+	shared x := Abc{ a: 12.5 }
+	shared y := Abc{ a: -7.5 }
+	shared z := Abc{ a: 13.125 }
+	a, b, c := rlock z, x, y { y.a, z.a, x.a }
+	assert a == -7.5
+	assert b == 13.125
+	assert c == 12.5
+}
+
+fn (mut st Abc) getvals(mut a Abc, mut b Abc) (f64, f64, f64) {
+	return a.a, st.a, b.a
+}
+
+fn test_mult_ret_method() {
+	shared x := Abc{ a: 12.5 }
+	shared y := Abc{ a: -7.5 }
+	shared z := Abc{ a: 13.125 }
+	a, b, c := lock z, x, y { z.getvals(mut x, mut y) }
+	assert a == 12.5
+	assert b == 13.125
+	assert c == -7.5
+}