1 files changed, 206 insertions, 0 deletions
diff --git a/compilerplugins/clang/unnecessaryvirtual.cxx b/compilerplugins/clang/unnecessaryvirtual.cxx
new file mode 100644
index 000000000..c3c73923b
--- /dev/null
+++ b/compilerplugins/clang/unnecessaryvirtual.cxx
@@ -0,0 +1,206 @@
+/* -*- 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 <cassert>
+#include <string>
+#include <iostream>
+#include <set>
+#include <unordered_set>
+#include "config_clang.h"
+#include "plugin.hxx"
+#include <fstream>
+
+/**
+Dump a list of virtual methods and a list of methods overriding virtual methods.
+Then we will post-process the 2 lists and find the set of virtual methods which don't need to be virtual.
+
+Also, we look for virtual methods where the bodies of all the overrides are empty i.e. this is leftover code
+that no longer has a purpose.
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE=all COMPILER_PLUGIN_TOOL='unnecessaryvirtual' check
+  $ ./compilerplugins/clang/unnecessaryvirtual.py
+  $ for dir in *; do make FORCE_COMPILE=all UPDATE_FILES=$dir COMPILER_PLUGIN_TOOL='removevirtuals' $dir; done
+
+Note that the actual process may involve a fair amount of undoing, hand editing, and general messing around
+to get it to work :-)
+
+TODO some boost bind stuff appears to confuse it, notably in the xmloff module
+*/
+
+namespace {
+
+struct MyFuncInfo
+{
+    std::string name;
+    std::string sourceLocation;
+
+};
+bool operator < (const MyFuncInfo &lhs, const MyFuncInfo &rhs)
+{
+    return lhs.name < rhs.name;
+}
+
+// try to limit the voluminous output a little
+static std::set<MyFuncInfo> definitionSet;
+static std::unordered_set<std::string> overridingSet;
+static std::unordered_set<std::string> nonEmptySet;
+
+class UnnecessaryVirtual:
+    public RecursiveASTVisitor<UnnecessaryVirtual>, public loplugin::Plugin
+{
+public:
+    explicit UnnecessaryVirtual(loplugin::InstantiationData const & data):
+        Plugin(data) {}
+
+    virtual void run() override
+    {
+        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
+
+        // dump all our output in one write call - this is to try and limit IO "crosstalk" between multiple processes
+        // writing to the same logfile
+        std::string output;
+        for (const MyFuncInfo & s : definitionSet)
+            output += "definition:\t" + s.name + "\t" + s.sourceLocation + "\n";
+        for (const std::string & s : overridingSet)
+            output += "overriding:\t" + s + "\n";
+        for (const std::string & s : nonEmptySet)
+            output += "nonempty:\t" + s + "\n";
+        std::ofstream myfile;
+        myfile.open( WORKDIR "/loplugin.unnecessaryvirtual.log", std::ios::app | std::ios::out);
+        myfile << output;
+        myfile.close();
+    }
+    bool shouldVisitTemplateInstantiations () const { return true; }
+    bool shouldVisitImplicitCode() const { return true; }
+
+    bool VisitCXXMethodDecl( const CXXMethodDecl* decl );
+private:
+    void MarkRootOverridesNonEmpty( const CXXMethodDecl* methodDecl );
+    std::string toString(SourceLocation loc);
+};
+
+std::string niceName(const CXXMethodDecl* cxxMethodDecl)
+{
+    while (cxxMethodDecl->getTemplateInstantiationPattern())
+        cxxMethodDecl = dyn_cast<CXXMethodDecl>(cxxMethodDecl->getTemplateInstantiationPattern());
+    while (cxxMethodDecl->getInstantiatedFromMemberFunction())
+        cxxMethodDecl = dyn_cast<CXXMethodDecl>(cxxMethodDecl->getInstantiatedFromMemberFunction());
+    std::string s = cxxMethodDecl->getReturnType().getCanonicalType().getAsString()
+        + " " + cxxMethodDecl->getQualifiedNameAsString() + "(";
+    for (const ParmVarDecl *pParmVarDecl : cxxMethodDecl->parameters()) {
+        s += pParmVarDecl->getType().getCanonicalType().getAsString();
+        s += ",";
+    }
+    s += ")";
+    if (cxxMethodDecl->isConst()) {
+        s += "const";
+    }
+    return s;
+}
+
+bool UnnecessaryVirtual::VisitCXXMethodDecl( const CXXMethodDecl* methodDecl )
+{
+    if (!methodDecl->isVirtual() || methodDecl->isDeleted()) {
+        return true;
+    }
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(methodDecl->getCanonicalDecl())) {
+        return true;
+    }
+
+    auto body = methodDecl->getBody();
+    if (body) {
+        auto compoundStmt = dyn_cast<CompoundStmt>(body);
+        if (!compoundStmt)
+            MarkRootOverridesNonEmpty(methodDecl->getCanonicalDecl());
+        else if (compoundStmt->size() > 0)
+            MarkRootOverridesNonEmpty(methodDecl->getCanonicalDecl());
+    }
+
+    if (!methodDecl->isThisDeclarationADefinition())
+        return true;
+
+    methodDecl = methodDecl->getCanonicalDecl();
+    if (!methodDecl)
+        return true;
+    std::string aNiceName = niceName(methodDecl);
+
+    // for destructors, we need to check if any of the superclass' destructors are virtual
+    if (isa<CXXDestructorDecl>(methodDecl)) {
+        const CXXRecordDecl* cxxRecordDecl = methodDecl->getParent();
+        if (cxxRecordDecl->getNumBases() == 0) {
+            definitionSet.insert( { aNiceName, toString( methodDecl->getLocation() ) } );
+            return true;
+        }
+        for(auto baseSpecifier = cxxRecordDecl->bases_begin();
+            baseSpecifier != cxxRecordDecl->bases_end(); ++baseSpecifier)
+        {
+            if (baseSpecifier->getType()->isRecordType())
+            {
+                const CXXRecordDecl* superclassCXXRecordDecl = baseSpecifier->getType()->getAsCXXRecordDecl();
+                if (superclassCXXRecordDecl->getDestructor())
+                {
+                    std::string aOverriddenNiceName = niceName(superclassCXXRecordDecl->getDestructor());
+                    overridingSet.insert(aOverriddenNiceName);
+                }
+            }
+        }
+        return true;
+    }
+
+    if (methodDecl->size_overridden_methods() == 0) {
+        definitionSet.insert( { aNiceName, toString( methodDecl->getLocation() ) } );
+    } else {
+       for (auto iter = methodDecl->begin_overridden_methods();
+            iter != methodDecl->end_overridden_methods(); ++iter)
+       {
+           const CXXMethodDecl *overriddenMethod = *iter;
+           // we only care about the first level override to establish that a virtual qualifier was useful.
+           if (overriddenMethod->isPure() || overriddenMethod->size_overridden_methods() == 0)
+           {
+               std::string aOverriddenNiceName = niceName(overriddenMethod);
+               overridingSet.insert(aOverriddenNiceName);
+           }
+        }
+    }
+    return true;
+}
+
+void UnnecessaryVirtual::MarkRootOverridesNonEmpty( const CXXMethodDecl* methodDecl )
+{
+    if (!methodDecl)
+        return;
+    if (methodDecl->size_overridden_methods() == 0) {
+        nonEmptySet.insert(niceName(methodDecl));
+        return;
+    }
+    for (auto iter = methodDecl->begin_overridden_methods();
+          iter != methodDecl->end_overridden_methods(); ++iter)
+    {
+        MarkRootOverridesNonEmpty(*iter);
+    }
+}
+
+std::string UnnecessaryVirtual::toString(SourceLocation loc)
+{
+    SourceLocation expansionLoc = compiler.getSourceManager().getExpansionLoc( loc );
+    StringRef name = getFilenameOfLocation(expansionLoc);
+    std::string sourceLocation = std::string(name.substr(strlen(SRCDIR)+1)) + ":" + std::to_string(compiler.getSourceManager().getSpellingLineNumber(expansionLoc));
+    loplugin::normalizeDotDotInFilePath(sourceLocation);
+    return sourceLocation;
+}
+
+
+loplugin::Plugin::Registration< UnnecessaryVirtual > X("unnecessaryvirtual", false);
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */