sk_sp: Covariant Move Constructor and Move Assignment

Also Covariant Copy Constructor, Copy Assignment,
and comparison operators.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1752093002

Review URL: https://codereview.chromium.org/1752093002

2 files changed, 102 insertions, 4 deletions

diff --git a/include/core/SkRefCnt.h b/include/core/SkRefCnt.h
index e2cf4456f8..02df993261 100644
--- a/include/core/SkRefCnt.h
+++ b/include/core/SkRefCnt.h
@@ -247,6 +247,9 @@ public:
      *  created sk_sp both have a reference to it.
      */
     sk_sp(const sk_sp<T>& that) : fPtr(SkSafeRef(that.get())) {}
+    template <typename U,
+              typename = skstd::enable_if_t<skstd::is_convertible<U, T>::value>>
+    sk_sp(const sk_sp<U>& that) : fPtr(SkSafeRef(that.get())) {}
 
     /**
      *  Move the underlying object from the argument to the newly created sk_sp. Afterwards only
@@ -254,6 +257,9 @@ public:
      *  No call to ref() or unref() will be made.
      */
     sk_sp(sk_sp<T>&& that) : fPtr(that.release()) {}
+    template <typename U,
+              typename = skstd::enable_if_t<skstd::is_convertible<U, T>::value>>
+    sk_sp(sk_sp<U>&& that) : fPtr(that.release()) {}
 
     /**
      *  Adopt the bare pointer into the newly created sk_sp.
@@ -268,7 +274,7 @@ public:
         SkSafeUnref(fPtr);
     }
 
-    sk_sp<T>& operator=(std::nullptr_t) { this->reset(); }
+    sk_sp<T>& operator=(std::nullptr_t) { this->reset(); return *this; }
 
     /**
      *  Shares the underlying object referenced by the argument by calling ref() on it. If this
@@ -279,6 +285,12 @@ public:
         this->reset(SkSafeRef(that.get()));
         return *this;
     }
+    template <typename U,
+              typename = skstd::enable_if_t<skstd::is_convertible<U, T>::value>>
+    sk_sp<T>& operator=(const sk_sp<U>& that) {
+        this->reset(SkSafeRef(that.get()));
+        return *this;
+    }
 
     /**
      *  Move the underlying object from the argument to the sk_sp. If the sk_sp previously held
@@ -289,12 +301,20 @@ public:
         this->reset(that.release());
         return *this;
     }
+    template <typename U,
+              typename = skstd::enable_if_t<skstd::is_convertible<U, T>::value>>
+    sk_sp<T>& operator=(sk_sp<U>&& that) {
+        this->reset(that.release());
+        return *this;
+    }
 
     bool operator==(std::nullptr_t) const { return this->get() == nullptr; }
     bool operator!=(std::nullptr_t) const { return this->get() != nullptr; }
 
-    bool operator==(const sk_sp<T>& that) const { return this->get() == that.get(); }
-    bool operator!=(const sk_sp<T>& that) const { return this->get() != that.get(); }
+    template <typename U>
+    bool operator==(const sk_sp<U>& that) const { return this->get() == that.get(); }
+    template <typename U>
+    bool operator!=(const sk_sp<U>& that) const { return this->get() != that.get(); }
 
     explicit operator bool() const { return this->get() != nullptr; }
 
diff --git a/tests/RefCntTest.cpp b/tests/RefCntTest.cpp
index e9d582d809..bda45317bc 100644
--- a/tests/RefCntTest.cpp
+++ b/tests/RefCntTest.cpp
@@ -134,11 +134,26 @@ public:
     }
 };
 
-DEF_TEST(sk_sp, reporter) {
+struct EffectImpl : public Effect {
+    static sk_sp<EffectImpl> Create() {
+        return sk_sp<EffectImpl>(new EffectImpl);
+    }
+    int fValue;
+};
+static sk_sp<Effect> make_effect() {
+    auto foo = EffectImpl::Create();
+    foo->fValue = 42;
+    return std::move(foo);
+}
+
+static void reset_counters() {
     gRefCounter = 0;
     gUnrefCounter = 0;
     gNewCounter = 0;
     gDeleteCounter = 0;
+}
+DEF_TEST(sk_sp, reporter) {
+    reset_counters();
 
     Paint paint;
     REPORTER_ASSERT(reporter, paint.fEffect.get() == nullptr);
@@ -167,5 +182,68 @@ DEF_TEST(sk_sp, reporter) {
 
     delete paint.get()->method();
     check(reporter, 2, 1, 2, 1);
+
+    paint.set(nullptr);
+    e = nullptr;
+    paint2.set(nullptr);
+    check(reporter, 2, 4, 2, 2);
+
+    reset_counters();
+    {
+        // Test convertible sk_sp assignment.
+        check(reporter, 0, 0, 0, 0);
+        sk_sp<Effect> foo(nullptr);
+        REPORTER_ASSERT(reporter, !foo);
+        foo = make_effect();
+        REPORTER_ASSERT(reporter, foo);
+        check(reporter, 0, 0, 1, 0);
+    }
+    check(reporter, 0, 1, 1, 1);
+
+    // Test passing convertible rvalue into funtion.
+    reset_counters();
+    paint.set(EffectImpl::Create());
+    check(reporter, 0, 0, 1, 0);
+    paint.set(nullptr);
+    check(reporter, 0, 1, 1, 1);
+
+    reset_counters();
+    auto baz = EffectImpl::Create();
+    check(reporter, 0, 0, 1, 0);
+    paint.set(std::move(baz));
+    check(reporter, 0, 0, 1, 0);
+    REPORTER_ASSERT(reporter, !baz);
+    paint.set(nullptr);
+    check(reporter, 0, 1, 1, 1);
+
+    reset_counters();
+    {
+        // test comparison operator with convertible type.
+        sk_sp<EffectImpl> bar1 = EffectImpl::Create();
+        sk_sp<Effect> bar2(bar1);  // convertible copy constructor
+        check(reporter, 1, 0, 1, 0);
+        REPORTER_ASSERT(reporter, bar1);
+        REPORTER_ASSERT(reporter, bar2);
+        REPORTER_ASSERT(reporter, bar1 == bar2);
+        REPORTER_ASSERT(reporter, bar2 == bar1);
+        REPORTER_ASSERT(reporter, !(bar1 != bar2));
+        REPORTER_ASSERT(reporter, !(bar2 != bar1));
+        sk_sp<Effect> bar3(nullptr);
+        bar3 = bar1;  // convertible copy assignment
+        check(reporter, 2, 0, 1, 0);
+
+    }
+    check(reporter, 2, 3, 1, 1);
+
+    // test passing convertible copy into funtion.
+    reset_counters();
+    baz = EffectImpl::Create();
+    check(reporter, 0, 0, 1, 0);
+    paint.set(baz);
+    check(reporter, 1, 0, 1, 0);
+    baz = nullptr;
+    check(reporter, 1, 1, 1, 0);
+    paint.set(nullptr);
+    check(reporter, 1, 2, 1, 1);
 }