AK: Stop allowing implicit downcast with RefPtr and NonnullRefPtr

We were allowing this dangerous kind of thing:

RefPtr<Base> base;
RefPtr<Derived> derived = base;

This patch changes the {Nonnull,}RefPtr constructors so this is no
longer possible.

To downcast one of these pointers, there is now static_ptr_cast<T>:

RefPtr<Derived> derived = static_ptr_cast<Derived>(base);

Fixing this exposed a ton of cowboy-downcasts in various places,
which we're now forced to fix. :^)

AK/NonnullRefPtr.h

@@ -68,7 +68,7 @@ public:
     template<typename U>
     RETURN_TYPESTATE(unconsumed)
     NonnullRefPtr(const U& object)
-        : m_ptr(&const_cast<T&>(static_cast<const T&>(object)))
+        : m_ptr(&const_cast<U&>(object))
     {
         m_ptr->ref();
     }
@@ -85,7 +85,7 @@ public:
     template<typename U>
     RETURN_TYPESTATE(unconsumed)
     NonnullRefPtr(NonnullRefPtr<U>&& other)
-        : m_ptr(static_cast<T*>(&other.leak_ref()))
+        : m_ptr(&other.leak_ref())
     {
     }
     RETURN_TYPESTATE(unconsumed)
@@ -97,7 +97,7 @@ public:
     template<typename U>
     RETURN_TYPESTATE(unconsumed)
     NonnullRefPtr(const NonnullRefPtr<U>& other)
-        : m_ptr(const_cast<T*>(static_cast<const T*>((other.ptr()))))
+        : m_ptr(const_cast<U*>(other.ptr()))
     {
         m_ptr->ref();
     }

AK/RefPtr.h

@@ -71,20 +71,20 @@ public:
     }
     template<typename U>
     RefPtr(const NonnullRefPtr<U>& other)
-        : m_ptr(static_cast<T*>(const_cast<U*>(other.ptr())))
+        : m_ptr(const_cast<U*>(other.ptr()))
     {
         ASSERT(m_ptr);
         m_ptr->ref();
     }
     template<typename U>
     RefPtr(NonnullRefPtr<U>&& other)
-        : m_ptr(static_cast<T*>(&other.leak_ref()))
+        : m_ptr(&other.leak_ref())
     {
         ASSERT(m_ptr);
     }
     template<typename U>
     RefPtr(RefPtr<U>&& other)
-        : m_ptr(static_cast<T*>(other.leak_ref()))
+        : m_ptr(other.leak_ref())
     {
     }
     RefPtr(const RefPtr& other)
@@ -94,7 +94,7 @@ public:
     }
     template<typename U>
     RefPtr(const RefPtr<U>& other)
-        : m_ptr(static_cast<T*>(const_cast<U*>(other.ptr())))
+        : m_ptr(const_cast<U*>(other.ptr()))
     {
         ref_if_not_null(m_ptr);
     }
@@ -282,6 +282,19 @@ struct Traits<RefPtr<T>> : public GenericTraits<RefPtr<T>> {
     static bool equals(const RefPtr<T>& a, const RefPtr<T>& b) { return a.ptr() == b.ptr(); }
 };
 
+template<typename T, typename U>
+inline NonnullRefPtr<T> static_ptr_cast(const NonnullRefPtr<U>& ptr)
+{
+    return NonnullRefPtr<T>(static_cast<const T&>(*ptr));
+}
+
+template<typename T, typename U>
+inline RefPtr<T> static_ptr_cast(const RefPtr<U>& ptr)
+{
+    return RefPtr<T>(static_cast<const T*>(ptr.ptr()));
+}
+
 }
 
 using AK::RefPtr;
+using AK::static_ptr_cast;

Applications/ChanViewer/BoardListModel.h

@@ -51,5 +51,5 @@ private:
     BoardListModel();
 
     JsonArray m_boards;
-    RefPtr<Core::HttpJob> m_pending_job;
+    RefPtr<Core::NetworkJob> m_pending_job;
 };

Applications/ChanViewer/ThreadCatalogModel.h

@@ -63,5 +63,5 @@ private:
 
     String m_board { "g" };
     JsonArray m_catalog;
-    RefPtr<Core::HttpJob> m_pending_job;
+    RefPtr<Core::NetworkJob> m_pending_job;
 };

Kernel/FileSystem/TmpFS.cpp

@@ -307,8 +307,8 @@ KResult TmpFSInode::add_child(InodeIdentifier child_id, const StringView& name,
 
     String owned_name = name;
     FS::DirectoryEntry entry = { owned_name.characters(), owned_name.length(), child_id, 0 };
-    RefPtr<Inode> child_tmp = fs().get_inode(child_id);
-    NonnullRefPtr<TmpFSInode> child = static_cast<NonnullRefPtr<TmpFSInode>>(child_tmp.release_nonnull());
+    auto child_tmp = fs().get_inode(child_id);
+    auto child = static_ptr_cast<TmpFSInode>(child_tmp.release_nonnull());
 
     m_children.set(owned_name, { entry, move(child) });
     set_metadata_dirty(true);

Libraries/LibJS/AST.h

@@ -137,11 +137,11 @@ class Declaration : public Statement {
 class FunctionNode {
 public:
     const FlyString& name() const { return m_name; }
-    const ScopeNode& body() const { return *m_body; }
+    const Statement& body() const { return *m_body; }
     const Vector<FlyString>& parameters() const { return m_parameters; };
 
 protected:
-    FunctionNode(const FlyString& name, NonnullRefPtr<ScopeNode> body, Vector<FlyString> parameters = {})
+    FunctionNode(const FlyString& name, NonnullRefPtr<Statement> body, Vector<FlyString> parameters = {})
         : m_name(name)
         , m_body(move(body))
         , m_parameters(move(parameters))
@@ -152,7 +152,7 @@ protected:
 
 private:
     FlyString m_name;
-    NonnullRefPtr<ScopeNode> m_body;
+    NonnullRefPtr<Statement> m_body;
     const Vector<FlyString> m_parameters;
 };
 
@@ -162,7 +162,7 @@ class FunctionDeclaration final
 public:
     static bool must_have_name() { return true; }
 
-    FunctionDeclaration(String name, NonnullRefPtr<ScopeNode> body, Vector<FlyString> parameters = {})
+    FunctionDeclaration(String name, NonnullRefPtr<Statement> body, Vector<FlyString> parameters = {})
         : FunctionNode(move(name), move(body), move(parameters))
     {
     }
@@ -179,7 +179,7 @@ class FunctionExpression final : public Expression
 public:
     static bool must_have_name() { return false; }
 
-    FunctionExpression(const FlyString& name, NonnullRefPtr<ScopeNode> body, Vector<FlyString> parameters = {})
+    FunctionExpression(const FlyString& name, NonnullRefPtr<Statement> body, Vector<FlyString> parameters = {})
         : FunctionNode(name, move(body), move(parameters))
     {
     }
@@ -241,14 +241,14 @@ private:
 
 class WhileStatement : public Statement {
 public:
-    WhileStatement(NonnullRefPtr<Expression> test, NonnullRefPtr<ScopeNode> body)
+    WhileStatement(NonnullRefPtr<Expression> test, NonnullRefPtr<Statement> body)
         : m_test(move(test))
         , m_body(move(body))
     {
     }
 
     const Expression& test() const { return *m_test; }
-    const ScopeNode& body() const { return *m_body; }
+    const Statement& body() const { return *m_body; }
 
     virtual Value execute(Interpreter&) const override;
     virtual void dump(int indent) const override;
@@ -257,19 +257,19 @@ private:
     virtual const char* class_name() const override { return "WhileStatement"; }
 
     NonnullRefPtr<Expression> m_test;
-    NonnullRefPtr<ScopeNode> m_body;
+    NonnullRefPtr<Statement> m_body;
 };
 
 class DoWhileStatement : public Statement {
 public:
-    DoWhileStatement(NonnullRefPtr<Expression> test, NonnullRefPtr<ScopeNode> body)
+    DoWhileStatement(NonnullRefPtr<Expression> test, NonnullRefPtr<Statement> body)
         : m_test(move(test))
         , m_body(move(body))
     {
     }
 
     const Expression& test() const { return *m_test; }
-    const ScopeNode& body() const { return *m_body; }
+    const Statement& body() const { return *m_body; }
 
     virtual Value execute(Interpreter&) const override;
     virtual void dump(int indent) const override;
@@ -278,12 +278,12 @@ private:
     virtual const char* class_name() const override { return "DoWhileStatement"; }
 
     NonnullRefPtr<Expression> m_test;
-    NonnullRefPtr<ScopeNode> m_body;
+    NonnullRefPtr<Statement> m_body;
 };
 
 class ForStatement : public Statement {
 public:
-    ForStatement(RefPtr<ASTNode> init, RefPtr<Expression> test, RefPtr<Expression> update, NonnullRefPtr<ScopeNode> body)
+    ForStatement(RefPtr<ASTNode> init, RefPtr<Expression> test, RefPtr<Expression> update, NonnullRefPtr<Statement> body)
         : m_init(move(init))
         , m_test(move(test))
         , m_update(move(update))
@@ -294,7 +294,7 @@ public:
     const ASTNode* init() const { return m_init; }
     const Expression* test() const { return m_test; }
     const Expression* update() const { return m_update; }
-    const ScopeNode& body() const { return *m_body; }
+    const Statement& body() const { return *m_body; }
 
     virtual Value execute(Interpreter&) const override;
     virtual void dump(int indent) const override;
@@ -305,7 +305,7 @@ private:
     RefPtr<ASTNode> m_init;
     RefPtr<Expression> m_test;
     RefPtr<Expression> m_update;
-    NonnullRefPtr<ScopeNode> m_body;
+    NonnullRefPtr<Statement> m_body;
 };
 
 enum class BinaryOp {
@@ -569,7 +569,7 @@ private:
     virtual const char* class_name() const override { return "UpdateExpression"; }
 
     UpdateOp m_op;
-    NonnullRefPtr<Identifier> m_argument;
+    NonnullRefPtr<Expression> m_argument;
     bool m_prefixed;
 };
 

Libraries/LibJS/Runtime/ScriptFunction.cpp

@@ -33,7 +33,7 @@
 
 namespace JS {
 
-ScriptFunction::ScriptFunction(const ScopeNode& body, Vector<FlyString> parameters)
+ScriptFunction::ScriptFunction(const Statement& body, Vector<FlyString> parameters)
     : m_body(body)
     , m_parameters(move(parameters))
 {

Libraries/LibJS/Runtime/ScriptFunction.h

@@ -32,10 +32,10 @@ namespace JS {
 
 class ScriptFunction final : public Function {
 public:
-    ScriptFunction(const ScopeNode& body, Vector<FlyString> parameters = {});
+    ScriptFunction(const Statement& body, Vector<FlyString> parameters = {});
     virtual ~ScriptFunction();
 
-    const ScopeNode& body() const { return m_body; }
+    const Statement& body() const { return m_body; }
     const Vector<FlyString>& parameters() const { return m_parameters; };
 
     virtual Value call(Interpreter&) override;
@@ -48,7 +48,7 @@ private:
     static Value length_getter(Interpreter&);
     static void length_setter(Interpreter&, Value);
 
-    NonnullRefPtr<ScopeNode> m_body;
+    NonnullRefPtr<Statement> m_body;
     const Vector<FlyString> m_parameters;
 };
 

Libraries/LibWeb/DOM/Document.cpp

@@ -221,7 +221,7 @@ void Document::layout()
 
     if (!m_layout_root) {
         LayoutTreeBuilder tree_builder;
-        m_layout_root = tree_builder.build(*this);
+        m_layout_root = static_ptr_cast<LayoutDocument>(tree_builder.build(*this));
     }
     m_layout_root->layout();
     m_layout_root->set_needs_display();

Libraries/LibWeb/Parser/CSSParser.cpp

@@ -153,39 +153,40 @@ NonnullRefPtr<StyleValue> parse_css_value(const StringView& string)
     return StringStyleValue::create(string);
 }
 
-RefPtr<StyleValue> parse_line_width(const StringView& part)
+RefPtr<LengthStyleValue> parse_line_width(const StringView& part)
 {
     NonnullRefPtr<StyleValue> value = parse_css_value(part);
     if (value->is_length())
-        return value;
+        return static_ptr_cast<LengthStyleValue>(value);
     return nullptr;
 }
 
-RefPtr<StyleValue> parse_color(const StringView& part)
+RefPtr<ColorStyleValue> parse_color(const StringView& part)
 {
     NonnullRefPtr<StyleValue> value = parse_css_value(part);
     if (value->is_color())
-        return value;
+        return static_ptr_cast<ColorStyleValue>(value);
     return nullptr;
 }
 
-RefPtr<StyleValue> parse_line_style(const StringView& part)
+RefPtr<StringStyleValue> parse_line_style(const StringView& part)
 {
-    NonnullRefPtr<StyleValue> value = parse_css_value(part);
-    if (value->is_string()) {
-        if (value->to_string() == "dotted")
-            return value;
-        if (value->to_string() == "dashed")
-            return value;
-        if (value->to_string() == "solid")
-            return value;
-        if (value->to_string() == "double")
-            return value;
-        if (value->to_string() == "groove")
-            return value;
-        if (value->to_string() == "ridge")
-            return value;
-    }
+    NonnullRefPtr<StyleValue> parsed_value = parse_css_value(part);
+    if (!parsed_value->is_string())
+        return nullptr;
+    auto value = static_ptr_cast<StringStyleValue>(parsed_value);
+    if (value->to_string() == "dotted")
+        return value;
+    if (value->to_string() == "dashed")
+        return value;
+    if (value->to_string() == "solid")
+        return value;
+    if (value->to_string() == "double")
+        return value;
+    if (value->to_string() == "groove")
+        return value;
+    if (value->to_string() == "ridge")
+        return value;
     return nullptr;
 }
 

Libraries/LibWeb/Parser/CSSParser.h

@@ -36,8 +36,8 @@ RefPtr<StyleDeclaration> parse_css_declaration(const StringView&);
 NonnullRefPtr<StyleValue> parse_css_value(const StringView&);
 Optional<Selector> parse_selector(const StringView&);
 
-RefPtr<StyleValue> parse_line_width(const StringView&);
-RefPtr<StyleValue> parse_color(const StringView&);
-RefPtr<StyleValue> parse_line_style(const StringView&);
+RefPtr<LengthStyleValue> parse_line_width(const StringView&);
+RefPtr<ColorStyleValue> parse_color(const StringView&);
+RefPtr<StringStyleValue> parse_line_style(const StringView&);
 
 }