1 files changed, 118 insertions, 0 deletions
diff --git a/src/checks/level0/writing-to-temporary.cpp b/src/checks/level0/writing-to-temporary.cpp
new file mode 100644
index 00000000..7467fa12
--- /dev/null
+++ b/src/checks/level0/writing-to-temporary.cpp
@@ -0,0 +1,118 @@
+/*
+   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 "writing-to-temporary.h"
+#include "Utils.h"
+#include "StringUtils.h"
+
+#include <clang/AST/AST.h>
+#include <clang/Lex/Lexer.h>
+
+using namespace clang;
+using namespace std;
+
+
+WritingToTemporary::WritingToTemporary(const std::string &name, ClazyContext *context)
+    : CheckBase(name, context, Option_CanIgnoreIncludes)
+    , m_widenCriteria(isOptionSet("widen-criteria"))
+{
+    m_filesToIgnore = { "qstring.h" };
+}
+
+static bool isDisallowedClass(const string &className)
+{
+    static const vector<string> disallowed = { "QTextCursor", "QDomElement", "KConfigGroup", "QWebElement",
+                                               "QScriptValue", "QTextLine", "QTextBlock", "QDomNode",
+                                               "QJSValue", "QTextTableCell" };
+    return clazy::contains(disallowed, className);
+}
+
+static bool isDisallowedMethod(const string &name)
+{
+    static const vector<string> disallowed = { "QColor::getCmyk", "QColor::getCmykF" };
+    return clazy::contains(disallowed, name);
+}
+
+static bool isKnownType(const string &className)
+{
+    static const vector<string> types = { "QList", "QVector", "QMap", "QHash", "QString", "QSet",
+                                          "QByteArray", "QUrl", "QVarLengthArray", "QLinkedList",
+                                          "QRect", "QRectF", "QBitmap", "QVector2D", "QVector3D",
+                                          "QVector4D", "QSize", "QSizeF", "QSizePolicy", "QPoint",
+                                          "QPointF", "QColor" };
+
+    return clazy::contains(types, className);
+}
+
+void WritingToTemporary::VisitStmt(clang::Stmt *stmt)
+{
+    CallExpr *callExpr = dyn_cast<CallExpr>(stmt);
+    if (!callExpr)
+        return;
+
+    if (shouldIgnoreFile(getLocStart(stmt)))
+        return;
+
+    // For a chain like getFoo().setBar(), returns {setBar(), getFoo()}
+    vector<CallExpr *> callExprs = Utils::callListForChain(callExpr); // callExpr is the call to setBar()
+    if (callExprs.size() < 2)
+        return;
+
+    CallExpr *firstCallToBeEvaluated = callExprs.at(callExprs.size() - 1); // This is the call to getFoo()
+    FunctionDecl *firstFunc = firstCallToBeEvaluated->getDirectCallee();
+    if (!firstFunc)
+        return;
+
+    CallExpr *secondCallToBeEvaluated = callExprs.at(callExprs.size() - 2); // This is the call to setBar()
+    FunctionDecl *secondFunc = secondCallToBeEvaluated->getDirectCallee();
+    if (!secondFunc)
+        return;
+
+    CXXMethodDecl *secondMethod = dyn_cast<CXXMethodDecl>(secondFunc);
+    if (!secondMethod || secondMethod->isConst() || secondMethod->isStatic())
+        return;
+
+    CXXRecordDecl *record = secondMethod->getParent();
+    if (!record || isDisallowedClass(record->getNameAsString()))
+        return;
+
+    QualType qt = firstFunc->getReturnType();
+    const Type *firstFuncReturnType = qt.getTypePtrOrNull();
+    if (!firstFuncReturnType || firstFuncReturnType->isPointerType() || firstFuncReturnType->isReferenceType())
+        return;
+
+    qt = secondFunc->getReturnType();
+    const Type *secondFuncReturnType = qt.getTypePtrOrNull();
+    if (!secondFuncReturnType || !secondFuncReturnType->isVoidType())
+        return;
+
+    if (!m_widenCriteria && !isKnownType(record->getNameAsString()) && !clazy::startsWith(secondFunc->getNameAsString(), "set"))
+        return;
+
+    const string &methodName = secondMethod->getQualifiedNameAsString();
+    if (isDisallowedMethod(methodName))
+        return;
+
+    emitWarning(getLocStart(stmt), "Call to temporary is a no-op: " + methodName);
+}