new loplugin:implinheritancehelper

Look for places we should be using ImplInheritanceHelper, which handles
various boilerplate for us

Change-Id: Icff6babf682c95b60aca86e6d6c2e2181eefc2f4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/144444
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

compilerplugins/clang/implinheritancehelper.cxx

@@ -0,0 +1,120 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <string>
+#include <iostream>
+
+#include "check.hxx"
+#include "plugin.hxx"
+#include "config_clang.h"
+#include "clang/AST/CXXInheritance.h"
+
+/**
+
+Look for places where we should be using ImplInheritanceHelper
+
+*/
+
+namespace
+{
+class ImplInheritanceHelper : public loplugin::FilteringPlugin<ImplInheritanceHelper>
+{
+public:
+    explicit ImplInheritanceHelper(loplugin::InstantiationData const& data)
+        : FilteringPlugin(data)
+    {
+    }
+
+    virtual bool preRun() override { return true; }
+
+    virtual void run() override
+    {
+        if (preRun())
+            TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+    bool VisitCXXRecordDecl(const CXXRecordDecl*);
+};
+
+bool ImplInheritanceHelper::VisitCXXRecordDecl(const CXXRecordDecl* cxxRecordDecl)
+{
+    if (ignoreLocation(cxxRecordDecl))
+        return true;
+    if (!cxxRecordDecl->isThisDeclarationADefinition())
+        return true;
+    if (cxxRecordDecl->isDependentContext())
+        return true;
+
+    // ignore the utility template classes
+    SourceLocation spellingLocation
+        = compiler.getSourceManager().getSpellingLoc(cxxRecordDecl->getBeginLoc());
+    StringRef fileName = getFilenameOfLocation(spellingLocation);
+    if (loplugin::hasPathnamePrefix(fileName, SRCDIR "/include/cppu"))
+        return true;
+    if (loplugin::isSamePathname(fileName, SRCDIR "/include/comphelper/compbase.hxx"))
+        return true;
+
+    // not sure why this extends XPropertyState but does not support it in queryInterface.
+    if (loplugin::DeclCheck(cxxRecordDecl)
+            .Class("ChainablePropertySet")
+            .Namespace("comphelper")
+            .GlobalNamespace())
+        return true;
+    // in these cases the UNO interface is optional
+    if (loplugin::DeclCheck(cxxRecordDecl).Class("OFSInputStreamContainer").GlobalNamespace())
+        return true;
+    if (loplugin::DeclCheck(cxxRecordDecl)
+            .Class("OPropertyBrowserController")
+            .Namespace("pcr")
+            .GlobalNamespace())
+        return true;
+
+    // check if this class extends cppu::WeakImplHelper
+    if (!loplugin::isDerivedFrom(cxxRecordDecl, [](Decl const* decl) -> bool {
+            return bool(loplugin::DeclCheck(decl)
+                            .Class("WeakImplHelper")
+                            .Namespace("cppu")
+                            .GlobalNamespace());
+        }))
+        return true;
+    // check if this class directly inherits from a UNO interface class
+    bool foundOne = false;
+    for (auto const& i : cxxRecordDecl->bases())
+    {
+        auto rt = i.getType()->getAs<RecordType>();
+        if (!rt)
+            continue;
+        auto const bd = cast<CXXRecordDecl>(rt->getDecl())->getDefinition();
+        auto ctx = bd->getDeclContext();
+        if (!ctx->isNamespace())
+            break;
+        auto ns = dyn_cast<NamespaceDecl>(ctx);
+        while (ns)
+        {
+            if (ns->getIdentifier() && ns->getName() == "star")
+            {
+                foundOne = true;
+                break;
+            }
+            ns = dyn_cast_or_null<NamespaceDecl>(ns->getParent());
+        }
+    }
+    if (!foundOne)
+        return true;
+    report(DiagnosticsEngine::Warning, "can probably use ImplInheritanceHelper here",
+           cxxRecordDecl->getLocation())
+        << cxxRecordDecl->getSourceRange();
+    return true;
+}
+
+loplugin::Plugin::Registration<ImplInheritanceHelper>
+    implinheritancehelper("implinheritancehelper");
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

compilerplugins/clang/test/implinheritancehelper.cxx

@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <sal/config.h>
+
+#include <com/sun/star/uno/XInterface.hpp>
+#include <com/sun/star/lang/XUnoTunnel.hpp>
+#include <cppuhelper/implbase.hxx>
+#include "com/sun/star/beans/XProperty.hpp"
+
+class VCLXDevice : public cppu::WeakImplHelper<css::lang::XUnoTunnel>
+{
+};
+
+// expected-error@+1 {{can probably use ImplInheritanceHelper here [loplugin:implinheritancehelper]}}
+class VCLXCheckBox : public css::beans::XProperty, public VCLXDevice
+{
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */

solenv/CompilerTest_compilerplugins_clang.mk

@@ -38,6 +38,7 @@ $(eval $(call gb_CompilerTest_add_exception_objects,compilerplugins_clang, \
     compilerplugins/clang/test/fragiledestructor \
     compilerplugins/clang/test/getstr \
     compilerplugins/clang/test/implicitboolconversion \
+    compilerplugins/clang/test/implinheritancehelper \
     compilerplugins/clang/test/indentation \
     compilerplugins/clang/test/intvsfloat \
     compilerplugins/clang/test/logexceptionnicely \