1 files changed, 267 insertions, 0 deletions
diff --git a/compilerplugins/clang/virtualdead.cxx b/compilerplugins/clang/virtualdead.cxx
new file mode 100644
index 000000000000..dd6e311193b8
--- /dev/null
+++ b/compilerplugins/clang/virtualdead.cxx
@@ -0,0 +1,267 @@
+/* -*- 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 "plugin.hxx"
+#include "check.hxx"
+
+#include <cassert>
+#include <string>
+#include <iostream>
+#include <set>
+#include <fstream>
+
+/**
+Look for virtual methods where all of the overrides either
+(a) do nothing
+(b) all return the same value
+
+The process goes something like this:
+  $ make check
+  $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='VirtualDead' check
+  $ ./compilerplugins/clang/VirtualDead.py
+  $ for dir in *; do make FORCE_COMPILE_ALL=1 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 :-)
+*/
+
+namespace
+{
+struct MyFuncInfo
+{
+    std::string name;
+    std::string sourceLocation;
+    std::string returnValue;
+};
+bool operator<(const MyFuncInfo& lhs, const MyFuncInfo& rhs)
+{
+    return std::tie(lhs.name, lhs.returnValue) < std::tie(rhs.name, rhs.returnValue);
+}
+
+// try to limit the voluminous output a little
+static std::set<MyFuncInfo> definitionSet;
+
+class VirtualDead : public RecursiveASTVisitor<VirtualDead>, public loplugin::Plugin
+{
+public:
+    explicit VirtualDead(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 += "virtual:\t" + s.name + "\t" + s.sourceLocation + "\t" + s.returnValue + "\n";
+        std::ofstream myfile;
+        myfile.open(WORKDIR "/loplugin.virtualdead.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:
+    std::string getCallValue(const Expr* arg);
+    std::string toString(SourceLocation loc);
+    void markSuperclassMethods(const CXXMethodDecl* methodDecl, std::string returnValue);
+};
+
+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 VirtualDead::VisitCXXMethodDecl(const CXXMethodDecl* methodDecl)
+{
+    if (ignoreLocation(methodDecl))
+        return true;
+    if (!methodDecl->isVirtual() || methodDecl->isDeleted())
+        return true;
+    if (isa<CXXDestructorDecl>(methodDecl))
+        return true;
+    // ignore stuff that forms part of the stable URE interface
+    if (isInUnoIncludeFile(methodDecl->getCanonicalDecl()))
+        return true;
+
+    if (!methodDecl->isThisDeclarationADefinition())
+        return true;
+
+    std::string returnValue;
+
+    auto body = methodDecl->getBody();
+    if (body)
+    {
+        auto compoundStmt = dyn_cast<CompoundStmt>(body);
+        if (!compoundStmt)
+            returnValue = "empty";
+        else if (compoundStmt->size() == 0)
+            returnValue = "empty";
+        else
+        {
+            if (auto returnStmt = dyn_cast<ReturnStmt>(*compoundStmt->body_begin()))
+            {
+                if (!returnStmt->getRetValue())
+                    returnValue = "empty";
+                else
+                    returnValue = getCallValue(returnStmt->getRetValue());
+            }
+            else
+                returnValue = "unknown-stmt";
+        }
+    }
+    else
+        returnValue = "empty";
+
+    markSuperclassMethods(methodDecl, returnValue);
+
+    return true;
+}
+
+void VirtualDead::markSuperclassMethods(const CXXMethodDecl* methodDecl, std::string returnValue)
+{
+    if (methodDecl->size_overridden_methods() == 0)
+    {
+        std::string aNiceName = niceName(methodDecl);
+        definitionSet.insert(
+            { aNiceName, toString(methodDecl->getCanonicalDecl()->getLocation()), returnValue });
+        return;
+    }
+
+    for (auto iter = methodDecl->begin_overridden_methods();
+         iter != methodDecl->end_overridden_methods(); ++iter)
+    {
+        const CXXMethodDecl* overriddenMethod = *iter;
+        markSuperclassMethods(overriddenMethod, returnValue);
+    }
+}
+
+std::string VirtualDead::getCallValue(const Expr* arg)
+{
+    arg = arg->IgnoreParenCasts();
+    if (isa<CXXDefaultArgExpr>(arg))
+    {
+        arg = dyn_cast<CXXDefaultArgExpr>(arg)->getExpr();
+    }
+    arg = arg->IgnoreParenCasts();
+    // ignore this, it seems to trigger an infinite recursion
+    if (isa<UnaryExprOrTypeTraitExpr>(arg))
+        return "unknown1";
+    if (arg->isValueDependent())
+        return "unknown2";
+    APSInt x1;
+    if (compat::EvaluateAsInt(arg, x1, compiler.getASTContext()))
+    {
+        return x1.toString(10);
+    }
+    if (isa<CXXNullPtrLiteralExpr>(arg))
+    {
+        return "0";
+    }
+    if (isa<MaterializeTemporaryExpr>(arg))
+    {
+        const CXXBindTemporaryExpr* strippedArg
+            = dyn_cast_or_null<CXXBindTemporaryExpr>(arg->IgnoreParenCasts());
+        if (strippedArg)
+        {
+            auto temp = dyn_cast<CXXTemporaryObjectExpr>(strippedArg->getSubExpr());
+            if (temp->getNumArgs() == 0)
+            {
+                if (loplugin::TypeCheck(temp->getType())
+                        .Class("OUString")
+                        .Namespace("rtl")
+                        .GlobalNamespace())
+                {
+                    return "\"\"";
+                }
+                if (loplugin::TypeCheck(temp->getType())
+                        .Class("OString")
+                        .Namespace("rtl")
+                        .GlobalNamespace())
+                {
+                    return "\"\"";
+                }
+                return "defaultConstruct";
+            }
+        }
+    }
+
+    // Get the expression contents.
+    // This helps us find params which are always initialised with something like "OUString()".
+    SourceManager& SM = compiler.getSourceManager();
+    SourceLocation startLoc = compat::getBeginLoc(arg);
+    SourceLocation endLoc = compat::getEndLoc(arg);
+    const char* p1 = SM.getCharacterData(startLoc);
+    const char* p2 = SM.getCharacterData(endLoc);
+    if (!p1 || !p2 || (p2 - p1) < 0 || (p2 - p1) > 40)
+    {
+        return "unknown3";
+    }
+    unsigned n = Lexer::MeasureTokenLength(endLoc, SM, compiler.getLangOpts());
+    std::string s(p1, p2 - p1 + n);
+    // strip linefeed and tab characters so they don't interfere with the parsing of the log file
+    std::replace(s.begin(), s.end(), '\r', ' ');
+    std::replace(s.begin(), s.end(), '\n', ' ');
+    std::replace(s.begin(), s.end(), '\t', ' ');
+
+    // now normalize the value. For some params, like OUString, we can pass it as OUString() or "" and they are the same thing
+    if (s == "OUString()")
+        s = "\"\"";
+    else if (s == "OString()")
+        s = "\"\"";
+    else if (s == "aEmptyOUStr") //sw
+        s = "\"\"";
+    else if (s == "EMPTY_OUSTRING") //sc
+        s = "\"\"";
+    else if (s == "GetEmptyOUString()") //sc
+        s = "\"\"";
+
+    if (s[0] == '"' || s[0] == '\'')
+        return s;
+    return "unknown4";
+}
+
+std::string VirtualDead::toString(SourceLocation loc)
+{
+    SourceLocation expansionLoc = compiler.getSourceManager().getExpansionLoc(loc);
+    StringRef name = compiler.getSourceManager().getFilename(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<VirtualDead> X("virtualdead", false);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */