# Cppcheck report - LibreOffice: compilerplugins/clang/inlinesimplememberfunctions.cxx

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    /* -*- 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 "plugin.hxx"
    #include "compat.hxx"

    // Methods that purely return a local field should be declared in the header and be declared inline.
    // So that the compiler can elide the function call and turn it into a simple fixed-offset-load instruction.

    namespace {

    class InlineSimpleMemberFunctions:
        public RecursiveASTVisitor<InlineSimpleMemberFunctions>, public loplugin::RewritePlugin
    {
    public:
        explicit InlineSimpleMemberFunctions(InstantiationData const & data): RewritePlugin(data) {}

        virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }

        bool VisitCXXMethodDecl(const CXXMethodDecl * decl);
    private:
        bool rewrite(const CXXMethodDecl * functionDecl);
    };

    static bool oneAndOnlyOne(clang::Stmt::const_child_range range) {
        if (range.empty()) {
            return false;
        }
        if ((++range.first) != range.second) {
            return false;
        }
        return true;
    }

    bool InlineSimpleMemberFunctions::VisitCXXMethodDecl(const CXXMethodDecl * functionDecl) {<--- The function 'VisitCXXMethodDecl' is never used.
        if (ignoreLocation(functionDecl)) {
            return true;
        }
        // no point in doing virtual methods, the compiler always has to generate a vtable entry and a method
        if (functionDecl->isVirtual()) {
            return true;
        }
        if (functionDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate) {
            return true;
        }
        if (!functionDecl->isInstance()) {
            return true;
        }
        if (!functionDecl->isOutOfLine()) {
            return true;
        }
        if( !functionDecl->hasBody()) {
            return true;
        }
        if( functionDecl->isInlineSpecified()) {
            return true;
        }
        if( functionDecl->getCanonicalDecl()->isInlineSpecified()) {
            return true;
        }
        if( functionDecl->getNameAsString().find("Impl") != std::string::npos) {
            return true;
        }
        // ignore stuff that forms part of the stable URE interface
        if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
                                  functionDecl->getCanonicalDecl()->getNameInfo().getLoc()))) {
            return true;
        }
        // ignore stuff like:
        //   template<class E> E * Sequence<E>::begin() { return getArray(); }
        if( functionDecl->getParent()->getDescribedClassTemplate() != nullptr ) {
            return true;
        }

        /*
          The chain here looks like
            CompoundStmt
              ReturnStmt
                other stuff
                  CXXThisExpr
        */

        const CompoundStmt* compoundStmt = dyn_cast< CompoundStmt >( functionDecl->getBody() );
        if (compoundStmt == nullptr) {
            return true;
        }
        if (compoundStmt->body_begin() == compoundStmt->body_end()) {
            return true;
        }

        const Stmt* childStmt = *compoundStmt->child_begin();

        if (dyn_cast<ReturnStmt>( childStmt ) == nullptr) {
            return true;
        }
        if (!oneAndOnlyOne(childStmt->children())) {
            return true;
        }

        /* Don't warn if we see a method definition like
             X X::a() {
                 return *this;
             }
          which translates to:
            CompoundStmt
              ReturnStmt
                ImplicitCastExpr
                  UnaryOperator
                    CXXThisExpr
          or:
            CompoundStmt
              ReturnStmt
                UnaryOperator
                  CXXThisExpr
        */
        childStmt = *childStmt->child_begin();
        if (dyn_cast<ImplicitCastExpr>( childStmt ) != nullptr
            && oneAndOnlyOne( childStmt->children() ))
        {
            const Stmt* childStmt2 = *childStmt->child_begin();
            if (dyn_cast<UnaryOperator>( childStmt2 ) != nullptr
                && oneAndOnlyOne(childStmt2->children()))
            {
                childStmt2 = *childStmt2->child_begin();
                if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
                    && childStmt2->children().empty())
                {
                    return true;
                }
            }
        }
        if (dyn_cast<UnaryOperator>( childStmt ) != nullptr
            && oneAndOnlyOne( childStmt->children() ))
        {
            const Stmt* childStmt2 = *childStmt->child_begin();
            if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
                && childStmt2->children().empty())
            {
                return true;
            }
        }

        /* look for a chains like:
           CompoundStmt
             ReturnStmt
               stuff
                 CXXThisExpr
        */
        childStmt = *(*compoundStmt->child_begin())->child_begin();
        while (1) {
            if (dyn_cast<CallExpr>( childStmt ) != nullptr)
                return true;
            if (dyn_cast<CXXNewExpr>( childStmt ) != nullptr)
                return true;
            if (dyn_cast<CXXConstructExpr>( childStmt ) != nullptr)
                return true;
            if (dyn_cast<ConditionalOperator>( childStmt ) != nullptr)
                return true;
            if (dyn_cast<BinaryOperator>( childStmt ) != nullptr)
                return true;
            // exclude methods that return fields on incomplete types .e.g the pImpl pattern
            const MemberExpr* memberExpr = dyn_cast<MemberExpr>( childStmt );
            if (memberExpr != nullptr && memberExpr->getMemberDecl()) {
                const FieldDecl* fieldDecl = dyn_cast<FieldDecl>(memberExpr->getMemberDecl());
                if (fieldDecl != nullptr)
                {
                    // yes, a little bit of a hack. However, it is quite hard to determine if the method
                    // in question is accessing a field via a pImpl pattern.
                    if (fieldDecl->getType()->isIncompleteType())
                        return true;
                    if (fieldDecl->getNameAsString().find("Impl") != std::string::npos)
                        return true;
                    if (fieldDecl->getNameAsString().find("pImp") != std::string::npos)
                        return true;
                    // somewhere in VCL
                    if (fieldDecl->getNameAsString().find("mpGlobalSyncData") != std::string::npos)
                        return true;
                    std::string s = fieldDecl->getType().getAsString();
                    if (s.find("Impl") != std::string::npos || s.find("pImp") != std::string::npos || s.find("Internal") != std::string::npos)
                        return true;
                }
            }
            if (dyn_cast<CXXThisExpr>( childStmt ) != nullptr) {
                if (!rewrite(functionDecl))
                {
                    report(
                        DiagnosticsEngine::Warning,
                        "inlinesimpleaccessmethods",
                        functionDecl->getSourceRange().getBegin())
                      << functionDecl->getSourceRange();
                    // display the location of the class member declaration so I don't have to search for it by hand
                    report(
                        DiagnosticsEngine::Note,
                        "inlinesimpleaccessmethods",
                        functionDecl->getCanonicalDecl()->getSourceRange().getBegin())
                      << functionDecl->getCanonicalDecl()->getSourceRange();
                    }
                 return true;
            }
            if ( childStmt->children().empty() )
                return true;
            childStmt = *childStmt->child_begin();
        }
        return true;
    }

    static std::string ReplaceString(std::string subject, const std::string& search,
                              const std::string& replace) {
        size_t pos = 0;
        while ((pos = subject.find(search, pos)) != std::string::npos) {
             subject.replace(pos, search.length(), replace);
             pos += replace.length();
        }
        return subject;
    }

    bool InlineSimpleMemberFunctions::rewrite(const CXXMethodDecl * functionDecl) {
        if (rewriter == nullptr) {
            return false;
        }
        // Only rewrite declarations in include files if a
        // definition is also seen, to avoid compilation of a
        // definition (in a main file only processed later) to fail
        // with a "mismatch" error before the rewriter had a chance
        // to act upon the definition.
        if (!compat::isInMainFile( compiler.getSourceManager(),
                   compiler.getSourceManager().getSpellingLoc(
                       functionDecl->getNameInfo().getLoc()))) {
            return false;
        }

        const char *p1, *p2;

        // get the function body contents
        p1 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocStart() );
        p2 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocEnd() );
        std::string s1( p1, p2 - p1 + 1);

        /* we can't safely move around stuff containing comments, we mess up the resulting code */
        if ( s1.find("/*") != std::string::npos || s1.find("//") != std::string::npos ) {
            return false;
        }

        // strip linefeeds and any double-spaces, so we have a max of one space between tokens
        s1 = ReplaceString(s1, "\r", "");
        s1 = ReplaceString(s1, "\n", "");
        s1 = ReplaceString(s1, "\t", " ");
        s1 = ReplaceString(s1, "  ", " ");
        s1 = ReplaceString(s1, "  ", " ");
        s1 = ReplaceString(s1, "  ", " ");
        s1 = " " + s1;

        // scan from the end of the function's body through the trailing whitespace, so we can do a nice clean remove
    // commented out because for some reason it will sometimes chomp an extra token
    //    SourceLocation endOfRemoveLoc = functionDecl->getBody()->getLocEnd();
    //    for (;;) {
    //        endOfRemoveLoc = endOfRemoveLoc.getLocWithOffset(1);
    //        p1 = compiler.getSourceManager().getCharacterData( endOfRemoveLoc );
    //        if (*p1 != ' ' && *p1 != '\r' && *p1 != '\n' && *p1 != '\t')
    //            break;
    //    }

        // remove the function's out of line body and declaration
        RewriteOptions opts;
        opts.RemoveLineIfEmpty = true;
        if (!removeText(SourceRange(functionDecl->getLocStart(), functionDecl->getBody()->getLocEnd()), opts)) {
            return false;
        }

        // scan forward until we find the semicolon
        const FunctionDecl * canonicalDecl = functionDecl->getCanonicalDecl();
        p1 = compiler.getSourceManager().getCharacterData( canonicalDecl->getLocEnd() );
        p2 = ++p1;
        while (*p2 != 0 && *p2 != ';') p2++;

        // insert the function body into the inline function definition (i.e. the one inside the class definition)
        return replaceText(canonicalDecl->getLocEnd().getLocWithOffset(p2 - p1 + 1), 1, s1);
    }

    loplugin::Plugin::Registration< InlineSimpleMemberFunctions > X("inlinesimplememberfunctions");

    }

    /* vim:set shiftwidth=4 softtabstop=4 expandtab: */