1 files changed, 117 insertions, 0 deletions
diff --git a/src/checks/level3/unneeded-cast.cpp b/src/checks/level3/unneeded-cast.cpp
new file mode 100644
index 00000000..d0b5e58f
--- /dev/null
+++ b/src/checks/level3/unneeded-cast.cpp
@@ -0,0 +1,117 @@
+/*
+   This file is part of the clazy static checker.
+
+  Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com
+  Author: Sérgio Martins <sergio.martins@kdab.com>
+
+  Copyright (C) 2015 Sergio Martins <smartins@kde.org>
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Library General Public
+  License as published by the Free Software Foundation; either
+  version 2 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Library General Public License for more details.
+
+  You should have received a copy of the GNU Library General Public License
+  along with this library; see the file COPYING.LIB.  If not, write to
+  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+  Boston, MA 02110-1301, USA.
+*/
+
+#include "unneeded-cast.h"
+#include "Utils.h"
+#include "QtUtils.h"
+#include "TypeUtils.h"
+#include "HierarchyUtils.h"
+#include "ClazyContext.h"
+
+#include <clang/AST/DeclCXX.h>
+#include <clang/AST/ExprCXX.h>
+
+using namespace llvm;
+using namespace clang;
+
+UnneededCast::UnneededCast(const std::string &name, ClazyContext *context)
+    : CheckBase(name, context, Option_CanIgnoreIncludes)
+{
+}
+
+void UnneededCast::VisitStmt(clang::Stmt *stm)
+{
+    if (handleNamedCast(dyn_cast<CXXNamedCastExpr>(stm)))
+        return;
+
+    handleQObjectCast(stm);
+}
+
+bool UnneededCast::handleNamedCast(CXXNamedCastExpr *namedCast)
+{
+    if (!namedCast)
+        return false;
+
+    const bool isDynamicCast = isa<CXXDynamicCastExpr>(namedCast);
+    const bool isStaticCast = isDynamicCast ? false : isa<CXXStaticCastExpr>(namedCast);
+
+    if (!isDynamicCast && !isStaticCast)
+        return false;
+
+    if (getLocStart(namedCast).isMacroID())
+        return false;
+
+    CXXRecordDecl *castFrom = namedCast ? Utils::namedCastInnerDecl(namedCast) : nullptr;
+    if (!castFrom || !castFrom->hasDefinition() || std::distance(castFrom->bases_begin(), castFrom->bases_end()) > 1)
+        return false;
+
+    if (isStaticCast) {
+        if (auto implicitCast = dyn_cast<ImplicitCastExpr>(namedCast->getSubExpr())) {
+            if (implicitCast->getCastKind() == CK_NullToPointer) {
+                // static_cast<Foo*>(0) is OK, and sometimes needed
+                return false;
+            }
+        }
+
+        // static_cast to base is needed in ternary operators
+        if (clazy::getFirstParentOfType<ConditionalOperator>(m_context->parentMap, namedCast) != nullptr)
+            return false;
+    }
+
+    if (isDynamicCast && !isOptionSet("prefer-dynamic-cast-over-qobject") && clazy::isQObject(castFrom))
+        emitWarning(getLocStart(namedCast), "Use qobject_cast rather than dynamic_cast");
+
+    CXXRecordDecl *castTo = Utils::namedCastOuterDecl(namedCast);
+    if (!castTo)
+        return false;
+
+    return maybeWarn(namedCast, castFrom, castTo);
+}
+
+bool UnneededCast::handleQObjectCast(Stmt *stm)
+{
+    CXXRecordDecl *castTo = nullptr;
+    CXXRecordDecl *castFrom = nullptr;
+
+    if (!clazy::is_qobject_cast(stm, &castTo, &castFrom))
+        return false;
+
+    return maybeWarn(stm, castFrom, castTo);
+}
+
+bool UnneededCast::maybeWarn(Stmt *stmt, CXXRecordDecl *castFrom, CXXRecordDecl *castTo)
+{
+    castFrom = castFrom->getCanonicalDecl();
+    castTo = castTo->getCanonicalDecl();
+
+    if (castFrom == castTo) {
+        emitWarning(getLocStart(stmt), "Casting to itself");
+        return true;
+    } else if (TypeUtils::derivesFrom(/*child=*/castFrom, castTo)) {
+        emitWarning(getLocStart(stmt), "explicitly casting to base is unnecessary");
+        return true;
+    }
+
+    return false;
+}