[sync] Add constexpr to EnumSet

components/sync/base/enum_set_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/sync/base/enum_set.h"
 
 #include <stddef.h>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 15 matching lines @@
 
 class EnumSetTest : public ::testing::Test {};
 
 TEST_F(EnumSetTest, ClassConstants) {
   TestEnumSet enums;
   EXPECT_EQ(TEST_MIN, TestEnumSet::kMinValue);
   EXPECT_EQ(TEST_MAX, TestEnumSet::kMaxValue);
   EXPECT_EQ(static_cast<size_t>(5), TestEnumSet::kValueCount);
 }
 
+// Use static_assert to check that functions we expect to be compile time
+// evaluatable are really that way.
+TEST_F(EnumSetTest, ConstexprsAreValid) {
+  static_assert(TestEnumSet::All().Has(TEST_1),
+                "expected All() to be integral constant expression");
+  static_assert(TestEnumSet::FromRange(TEST_1, TEST_3).Has(TEST_1),
+                "expected FromRange() to be integral constant expression");
+  static_assert(TestEnumSet(TEST_1).Has(TEST_1),
+                "expected TestEnumSet() to be integral constant expression");
+}
+
 TEST_F(EnumSetTest, DefaultConstructor) {
   const TestEnumSet enums;
   EXPECT_TRUE(enums.Empty());
   EXPECT_EQ(static_cast<size_t>(0), enums.Size());
   EXPECT_FALSE(enums.Has(TEST_0));
   EXPECT_FALSE(enums.Has(TEST_1));
   EXPECT_FALSE(enums.Has(TEST_2));
   EXPECT_FALSE(enums.Has(TEST_3));
   EXPECT_FALSE(enums.Has(TEST_4));
 }
@@ skipping 45 matching lines @@
   EXPECT_TRUE(enums.Has(TEST_2));
   EXPECT_TRUE(enums.Has(TEST_3));
   EXPECT_TRUE(enums.Has(TEST_4));
 }
 
 TEST_F(EnumSetTest, FromRange) {
   EXPECT_EQ(TestEnumSet(TEST_1, TEST_2, TEST_3),
             TestEnumSet::FromRange(TEST_1, TEST_3));
   EXPECT_EQ(TestEnumSet::All(), TestEnumSet::FromRange(TEST_0, TEST_4));
   EXPECT_EQ(TestEnumSet(TEST_1), TestEnumSet::FromRange(TEST_1, TEST_1));
+
+  using RestrictedRangeSet = EnumSet<TestEnum, TEST_1, TEST_MAX>;
+  EXPECT_EQ(RestrictedRangeSet(TEST_1, TEST_2, TEST_3),
+            RestrictedRangeSet::FromRange(TEST_1, TEST_3));
+  EXPECT_EQ(RestrictedRangeSet::All(),
+            RestrictedRangeSet::FromRange(TEST_1, TEST_4));
 }
 
 TEST_F(EnumSetTest, Put) {
   TestEnumSet enums(TEST_3);
   enums.Put(TEST_2);
   EXPECT_EQ(TestEnumSet(TEST_2, TEST_3), enums);
   enums.Put(TEST_4);
   EXPECT_EQ(TestEnumSet(TEST_2, TEST_3, TEST_4), enums);
 }
 
@@ skipping 94 matching lines @@
 TEST_F(EnumSetTest, Difference) {
   const TestEnumSet enums1(TEST_3, TEST_4);
   const TestEnumSet enums2(TEST_2, TEST_3);
   const TestEnumSet enums3 = Difference(enums1, enums2);
 
   EXPECT_EQ(TestEnumSet(TEST_4), enums3);
 }
 
 }  // namespace
 }  // namespace syncer