Move swap() under base namespace

This is needed because of how argument-dependent lookup works (it
looks in the namespace of the type for an unqualified function name).

According to go/using-std-swap, the recommended usage pattern is:
  using std::swap;
  swap(thing1, thing2);
Having swap outside of base namespace wouldn't work with this
recommendation as slower std::swap would be silently used instead.

Bug: 1073933
Change-Id: Ib4485b51ba52ad491306bec9b4402a154adae16c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2167796
Auto-Submit: Bartek Nowierski <bartekn@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763350}

base/memory/checked_ptr.h

@@ -80,13 +80,13 @@ class CheckedPtr {
   T* ptr_ = nullptr;
 };
 
-}  // namespace base
-
-using base::CheckedPtr;
-
 template <typename T>
 void swap(CheckedPtr<T>& lhs, CheckedPtr<T>& rhs) noexcept {
   lhs.swap(rhs);
 }
 
+}  // namespace base
+
+using base::CheckedPtr;
+
 #endif  // BASE_MEMORY_CHECKED_PTR_H_

base/memory/checked_ptr_unittest.cc

@@ -11,8 +11,6 @@
 
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace base {
-
 // This helps when copying arrays/vectors of pointers.
 static_assert(std::is_trivially_copyable<CheckedPtr<void>>::value,
               "CheckedPtr should be trivially copyable");
@@ -33,8 +31,6 @@ struct Derived : MyStruct {
   int y;
 };
 
-}  // namespace
-
 TEST(CheckedPtr, NullStarDereference) {
   CheckedPtr<int> ptr;
   EXPECT_DEATH_IF_SUPPORTED(if (*ptr == 42) return, "");
@@ -183,4 +179,4 @@ TEST(CheckedPtr, AdvanceString) {
   }
 }
 
-}  // namespace base
+}  // namespace

base/memory/checked_ptr_unittest.nc

@@ -9,7 +9,7 @@
 
 #include "base/memory/checked_ptr.h"
 
-namespace base {
+namespace {
 
 struct Producer {};
 struct DerivedProducer : Producer {};
@@ -17,7 +17,7 @@ struct OtherDerivedProducer : Producer {};
 struct Unrelated {};
 struct DerivedUnrelated : Unrelated {};
 
-#if defined(NCTEST_AUTO_DOWNCAST)  // [r"no viable conversion from 'CheckedPtr<base::Producer>' to 'CheckedPtr<base::DerivedProducer>'"]
+#if defined(NCTEST_AUTO_DOWNCAST)  // [r"no viable conversion from 'CheckedPtr<\(anonymous namespace\)::Producer>' to 'CheckedPtr<\(anonymous namespace\)::DerivedProducer>'"]
 
 void WontCompile() {
   Producer f;
@@ -25,7 +25,7 @@ void WontCompile() {
   CheckedPtr<DerivedProducer> derived_ptr = ptr;
 }
 
-#elif defined(NCTEST_STATIC_DOWNCAST)  // [r"no matching conversion for static_cast from 'CheckedPtr<base::Producer>' to 'CheckedPtr<base::DerivedProducer>'"]
+#elif defined(NCTEST_STATIC_DOWNCAST)  // [r"no matching conversion for static_cast from 'CheckedPtr<\(anonymous namespace\)::Producer>' to 'CheckedPtr<\(anonymous namespace\)::DerivedProducer>'"]
 
 void WontCompile() {
   Producer f;
@@ -34,7 +34,7 @@ void WontCompile() {
       static_cast<CheckedPtr<DerivedProducer>>(ptr);
 }
 
-#elif defined(NCTEST_AUTO_REF_DOWNCAST)  // [r"non-const lvalue reference to type 'CheckedPtr<base::DerivedProducer>' cannot bind to a value of unrelated type 'CheckedPtr<base::Producer>'"]
+#elif defined(NCTEST_AUTO_REF_DOWNCAST)  // [r"non-const lvalue reference to type 'CheckedPtr<\(anonymous namespace\)::DerivedProducer>' cannot bind to a value of unrelated type 'CheckedPtr<\(anonymous namespace\)::Producer>'"]
 
 void WontCompile() {
   Producer f;
@@ -42,7 +42,7 @@ void WontCompile() {
   CheckedPtr<DerivedProducer>& derived_ptr = ptr;
 }
 
-#elif defined(NCTEST_STATIC_REF_DOWNCAST)  // [r"non-const lvalue reference to type 'CheckedPtr<base::DerivedProducer>' cannot bind to a value of unrelated type 'CheckedPtr<base::Producer>'"]
+#elif defined(NCTEST_STATIC_REF_DOWNCAST)  // [r"non-const lvalue reference to type 'CheckedPtr<\(anonymous namespace\)::DerivedProducer>' cannot bind to a value of unrelated type 'CheckedPtr<\(anonymous namespace\)::Producer>'"]
 
 void WontCompile() {
   Producer f;
@@ -51,21 +51,21 @@ void WontCompile() {
       static_cast<CheckedPtr<DerivedProducer>&>(ptr);
 }
 
-#elif defined(NCTEST_AUTO_DOWNCAST_FROM_RAW) // [r"no viable conversion from 'base::Producer \*' to 'CheckedPtr<base::DerivedProducer>'"]
+#elif defined(NCTEST_AUTO_DOWNCAST_FROM_RAW) // [r"no viable conversion from '\(anonymous namespace\)::Producer \*' to 'CheckedPtr<\(anonymous namespace\)::DerivedProducer>'"]
 
 void WontCompile() {
   Producer f;
   CheckedPtr<DerivedProducer> ptr = &f;
 }
 
-#elif defined(NCTEST_UNRELATED_FROM_RAW) // [r"no viable conversion from 'base::DerivedProducer \*' to 'CheckedPtr<base::Unrelated>'"]
+#elif defined(NCTEST_UNRELATED_FROM_RAW) // [r"no viable conversion from '\(anonymous namespace\)::DerivedProducer \*' to 'CheckedPtr<\(anonymous namespace\)::Unrelated>'"]
 
 void WontCompile() {
   DerivedProducer f;
   CheckedPtr<Unrelated> ptr = &f;
 }
 
-#elif defined(NCTEST_UNRELATED_STATIC_FROM_WRAPPED) // [r"static_cast from 'base::DerivedProducer \*' to 'base::Unrelated \*', which are not related by inheritance, is not allowed"]
+#elif defined(NCTEST_UNRELATED_STATIC_FROM_WRAPPED) // [r"static_cast from '\(anonymous namespace\)::DerivedProducer \*' to '\(anonymous namespace\)::Unrelated \*', which are not related by inheritance, is not allowed"]
 
 void WontCompile() {
   DerivedProducer f;
@@ -83,4 +83,4 @@ void WontCompile() {
 
 #endif
 
-}  // namespace base
+}  // namespace