/* -*- 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 "plugin.hxx"

namespace {

// Like clang::Stmt::IgnoreImplicit (lib/AST/Stmt.cpp), but also looking through implicit
// UserDefinedConversion's member function call:
Expr const * ignoreAllImplicit(Expr const * expr) {
    if (auto const e = dyn_cast<ExprWithCleanups>(expr)) {
        expr = e->getSubExpr();
    }
    if (auto const e = dyn_cast<MaterializeTemporaryExpr>(expr)) {
        expr = e->GetTemporaryExpr();
    }
    if (auto const e = dyn_cast<CXXBindTemporaryExpr>(expr)) {
        expr = e->getSubExpr();
    }
    while (auto const e = dyn_cast<ImplicitCastExpr>(expr)) {
        expr = e->getSubExpr();
        if (e->getCastKind() == CK_UserDefinedConversion) {
            auto const ce = cast<CXXMemberCallExpr>(expr);
            assert(ce->getNumArgs() == 0);
            expr = ce->getImplicitObjectArgument();
        }
    }
    return expr;
}

Expr const * ignoreParenImpCastAndComma(Expr const * expr) {
    for (;;) {
        expr = expr->IgnoreParenImpCasts();
        auto e = dyn_cast<BinaryOperator>(expr);
        if (e == nullptr || e->getOpcode() != BO_Comma) {
            return expr;
        }
        expr = e->getRHS();
    }
}

Expr const * getSubExprOfLogicalNegation(Expr const * expr) {
    auto e = dyn_cast<UnaryOperator>(ignoreParenImpCastAndComma(expr));
    return e == nullptr || e->getOpcode() != UO_LNot
        ? nullptr : e->getSubExpr();
}

// Search for an operator with matching parameter types; while this may miss some operators with
// odd parameter types that would actually be used by the compiler, it is overall better to have too
// many false negatives (i.e., miss valid loplugin:simplifybool warnings) than false positives here:
FunctionDecl const * findOperator(CompilerInstance& compiler, clang::RecordType const * recordType, BinaryOperator::Opcode opcode, QualType lhs, QualType rhs) {
    auto const clhs = lhs.isNull() ? nullptr : lhs.getCanonicalType().getTypePtr();
    auto const crhs = rhs.getCanonicalType().getTypePtr();
    OverloadedOperatorKind over = BinaryOperator::getOverloadedOperator(opcode);
    CXXRecordDecl const * recordDecl = dyn_cast<CXXRecordDecl>(recordType->getDecl());
    if (!recordDecl)
        return nullptr;
    // search for member overloads
    for (auto it = recordDecl->method_begin(); it != recordDecl->method_end(); ++it) {
        if (it->getOverloadedOperator() == over) {
            assert(it->getNumParams() == 1);
            if (it->getParamDecl(0)->getType().getCanonicalType().getTypePtr() == crhs)
                return *it;
        }
    }
    // search for free function overloads
    auto ctx = recordDecl->getDeclContext();
    if (ctx->getDeclKind() == Decl::LinkageSpec) {
        ctx = ctx->getParent();
    }
    auto declName = compiler.getASTContext().DeclarationNames.getCXXOperatorName(over);
    auto res = ctx->lookup(declName);
    for (auto d = res.begin(); d != res.end(); ++d) {
        FunctionDecl const * f = dyn_cast<FunctionDecl>(*d);
        if (!f || f->getNumParams() != 2)
            continue;
        if (f->getParamDecl(1)->getType().getCanonicalType().getTypePtr() != crhs)
            continue;
        auto const p0 = f->getParamDecl(0)->getType().getCanonicalType().getTypePtr();
        if (clhs) {
            if (p0 != clhs)
                continue;
        } else {
            if (p0 != recordType) {
                auto lvalue = dyn_cast<LValueReferenceType>(p0);
                if (!lvalue)
                    continue;
                if (lvalue->getPointeeType().getTypePtr() != recordType)
                    continue;
            }
        }
        return f;
    }
    return nullptr;
}

enum class Value { Unknown, False, True };

Value getValue(Expr const * expr) {
    expr = ignoreParenImpCastAndComma(expr);
    if (expr->getType()->isBooleanType()) {
        // Instead going via Expr::isCXX11ConstantExpr would turn up exactly one
        // additional place in svx/source/dialog/framelinkarray.cxx
        //
        //   const bool DIAG_DBL_CLIP_DEFAULT = false;
        //   ...
        //   ... = mxImpl.get() ? mxImpl->mbDiagDblClip : DIAG_DBL_CLIP_DEFAULT;
        //
        // where it is unclear whether it is not actually better to consider
        // DIAG_DBL_CLIP_DEFAULT a tunable parameter (and thus not to simplify):
        auto lit = dyn_cast<CXXBoolLiteralExpr>(expr);
        if (lit != nullptr) {
            return lit->getValue() ? Value::True : Value::False;
        }
    }
    return Value::Unknown;
}

class SimplifyBool:
    public loplugin::FilteringPlugin<SimplifyBool>
{
public:
    explicit SimplifyBool(loplugin::InstantiationData const & data):
        FilteringPlugin(data) {}

    void run() override;

    bool VisitUnaryLNot(UnaryOperator const * expr);

    bool VisitBinLT(BinaryOperator const * expr);

    bool VisitBinGT(BinaryOperator const * expr);

    bool VisitBinLE(BinaryOperator const * expr);

    bool VisitBinGE(BinaryOperator const * expr);

    bool VisitBinEQ(BinaryOperator const * expr);

    bool VisitBinNE(BinaryOperator const * expr);

    bool VisitConditionalOperator(ConditionalOperator const * expr);

    bool TraverseFunctionDecl(FunctionDecl *);

    bool TraverseCXXMethodDecl(CXXMethodDecl *);

private:
    FunctionDecl* m_insideFunctionDecl = nullptr;
};

void SimplifyBool::run() {
    if (compiler.getLangOpts().CPlusPlus) {
        TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
    }
}

bool SimplifyBool::VisitUnaryLNot(UnaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    auto e = getSubExprOfLogicalNegation(expr->getSubExpr());
    if (e) {
        // Ignore macros, otherwise
        //    OSL_ENSURE(!b, ...);
        // triggers.
        if (compat::getBeginLoc(e).isMacroID())
            return true;
        // double logical not of an int is an idiom to convert to bool
        auto const sub = ignoreAllImplicit(e);
        if (!sub->getType()->isBooleanType())
            return true;
        report(
            DiagnosticsEngine::Warning,
            ("double logical negation expression of the form '!!A' (with A of type"
             " %0) can %select{logically|literally}1 be simplified as 'A'"),
            compat::getBeginLoc(expr))
            << sub->getType()
            << sub->getType()->isBooleanType()
            << expr->getSourceRange();
        return true;
    }
    if (auto binaryOp = dyn_cast<BinaryOperator>(expr->getSubExpr()->IgnoreParenImpCasts())) {
        // Ignore macros, otherwise
        //    OSL_ENSURE(!b, ...);
        // triggers.
        if (compat::getBeginLoc(binaryOp).isMacroID())
            return true;
        if (binaryOp->isComparisonOp())
        {
            auto t = binaryOp->getLHS()->IgnoreImpCasts()->getType()->getUnqualifiedDesugaredType();
            if (t->isTemplateTypeParmType() || t->isDependentType() || t->isRecordType())
                return true;
            // for floating point (with NaN) !(x<y) need not be equivalent to x>=y
            if (t->isFloatingType() ||
                binaryOp->getRHS()->IgnoreImpCasts()->getType()->getUnqualifiedDesugaredType()->isFloatingType())
                return true;
            report(
                DiagnosticsEngine::Warning,
                ("logical negation of comparison operator, can be simplified by inverting operator"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
        }
        else if (binaryOp->isLogicalOp())
        {
            auto containsNegation = [](Expr const * expr) {
                expr = ignoreParenImpCastAndComma(expr);
                if (auto unaryOp = dyn_cast<UnaryOperator>(expr))
                    if (unaryOp->getOpcode() == UO_LNot)
                        return expr;
                if (auto binaryOp = dyn_cast<BinaryOperator>(expr))
                    if (binaryOp->getOpcode() == BO_NE)
                        return expr;
                if (auto cxxOpCall = dyn_cast<CXXOperatorCallExpr>(expr))
                    if (cxxOpCall->getOperator() == OO_ExclaimEqual)
                        return expr;
                return (Expr const*)nullptr;
            };
            auto lhs = containsNegation(binaryOp->getLHS());
            auto rhs = containsNegation(binaryOp->getRHS());
            if (!lhs || !rhs)
                return true;
            if (lhs || rhs)
                report(
                    DiagnosticsEngine::Warning,
                    ("logical negation of logical op containing negation, can be simplified"),
                    compat::getBeginLoc(binaryOp))
                    << binaryOp->getSourceRange();
        }
    }
    if (auto binaryOp = dyn_cast<CXXOperatorCallExpr>(expr->getSubExpr()->IgnoreParenImpCasts())) {
        // Ignore macros, otherwise
        //    OSL_ENSURE(!b, ...);
        // triggers.
        if (compat::getBeginLoc(binaryOp).isMacroID())
            return true;
        auto op = binaryOp->getOperator();
        // Negating things like > and >= would probably not be wise, there is no guarantee the negation holds for operator overloaded types.
        // However, == and != are normally considered ok.
        if (!(op == OO_EqualEqual || op == OO_ExclaimEqual))
            return true;
        BinaryOperator::Opcode negatedOpcode = BinaryOperator::negateComparisonOp(BinaryOperator::getOverloadedOpcode(op));
        auto t = binaryOp->getArg(0)->IgnoreImpCasts()->getType()->getUnqualifiedDesugaredType();
        // we need to verify that a negated operator actually existed
        if (!t->isRecordType())
            return true;
        auto recordType = dyn_cast<RecordType>(t);
        auto const fdecl = binaryOp->getDirectCallee();
        if (!fdecl) // e.g. CXXOperatorCallExpr with UnresolvedLookupExpr
            return true;
        QualType lhs;
        QualType rhs;
        if (auto const mdecl = dyn_cast<CXXMethodDecl>(fdecl)) {
            assert(fdecl->getNumParams() == 1);
            rhs = fdecl->getParamDecl(0)->getType();
        } else {
            assert(fdecl->getNumParams() == 2);
            lhs = fdecl->getParamDecl(0)->getType();
            rhs = fdecl->getParamDecl(1)->getType();
        }
        auto const negOp = findOperator(compiler, recordType, negatedOpcode, lhs, rhs);
        if (!negOp)
            return true;
        // if we are inside a similar operator, ignore, eg. operator!= is often defined by calling !operator==
        if (m_insideFunctionDecl && m_insideFunctionDecl->getNumParams() >= 1) {
            auto qt = m_insideFunctionDecl->getParamDecl(0)->getType();
            auto lvalue = dyn_cast<LValueReferenceType>(qt.getTypePtr());
            if (lvalue && lvalue->getPointeeType()->getUnqualifiedDesugaredType() == recordType)
                return true;
        }
        // QA code
        StringRef fn(handler.getMainFileName());
        if (loplugin::isSamePathname(fn, SRCDIR "/testtools/source/bridgetest/bridgetest.cxx"))
            return true;
        report(
            DiagnosticsEngine::Warning,
            ("logical negation of comparison operator, can be simplified by inverting operator"),
            compat::getBeginLoc(expr))
            << expr->getSourceRange();
        report(
            DiagnosticsEngine::Note, "the presumed corresponding negated operator is declared here",
            negOp->getLocation())
            << negOp->getSourceRange();
    }
    return true;
}

bool SimplifyBool::VisitBinLT(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'A < false' (with A of type"
                 " %0) can logically be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::True:
            {
                auto e = getSubExprOfLogicalNegation(expr->getLHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("less-than expression of the form 'A < true' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getLHS()->IgnoreImpCasts()->getType()
                        << (expr->getLHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("less-than expression of the form '!A < true' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'false < A' (with A of type"
                 " %0) can %select{logically|literally}1 be simplified as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'false < false' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'false < true' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'true < A' (with A of type"
                 " %0) can logically be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'true < false' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("less-than expression of the form 'true < true' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitBinGT(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'A > false' (with A of"
                 " type %0) can %select{logically|literally}1 be simplified as"
                 " 'A'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'A > true' (with A of"
                 " type %0) can logically be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'false > A' (with A of"
                 " type %0) can logically be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'false > false' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'false > true' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            {
                auto e = getSubExprOfLogicalNegation(expr->getRHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("greater-than expression of the form 'true > A' (with"
                         " A of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getRHS()->IgnoreImpCasts()->getType()
                        << (expr->getRHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("greater-than expression of the form 'true > !A' (with"
                         " A of type %0) can %select{logically|literally}1 be"
                         " simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'true > false' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than expression of the form 'true > true' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitBinLE(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            {
                auto e = getSubExprOfLogicalNegation(expr->getLHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("less-than-or-equal-to expression of the form 'A <="
                         " false' (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as"
                         " '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getLHS()->IgnoreImpCasts()->getType()
                        << (expr->getLHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("less-than-or-equal-to expression of the form '!A <="
                         " false' (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'A <= true'"
                 " (with A of type %0) can logically be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'false <= A'"
                 " (with A of type %0) can logically be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'false <= false'"
                 " can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'false <= true'"
                 " can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'true <= A'"
                 " (with A of type %0) can %select{logically|literally}1 be"
                 " simplified as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'true <= false'"
                 " can literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("less-than-or-equal-to expression of the form 'true <= true'"
                 " can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitBinGE(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'A >= false'"
                 " (with A of type %0) can logically be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'A >= true'"
                 " (with A of type %0) can %select{logically|literally}1 be"
                 " simplified as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            {
                auto e = getSubExprOfLogicalNegation(expr->getRHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("greater-than-or-equal-to expression of the form"
                         " 'false >= A' (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as"
                         " '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getRHS()->IgnoreImpCasts()->getType()
                        << (expr->getRHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("greater-than-or-equal-to expression of the form"
                         " 'false >= !A' (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'false >="
                 " false' can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'false >="
                 " true' can literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'true >= A'"
                 " (with A of type %0) can logically be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'true >="
                 " false' can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("greater-than-or-equal-to expression of the form 'true >="
                 " true' can literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitBinEQ(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            {
                auto e = getSubExprOfLogicalNegation(expr->getLHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("equal-to expression of the form 'A == false' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getLHS()->IgnoreImpCasts()->getType()
                        << (expr->getLHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("equal-to expression of the form '!A == false' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'A == true' (with A of type"
                 " %0) can %select{logically|literally}1 be simplified as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            {
                auto e = getSubExprOfLogicalNegation(expr->getRHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("equal-to expression of the form 'false == A' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getRHS()->IgnoreImpCasts()->getType()
                        << (expr->getRHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("equal-to expression of the form 'false == !A' (with A"
                         " of type %0) can %select{logically|literally}1 be"
                         " simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'false == false' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'false == true' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'true == A' (with A of type"
                 " %0) can %select{logically|literally}1 be simplified as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'true == false' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("equal-to expression of the form 'true == true' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitBinNE(BinaryOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    if (!(expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
          && expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()))
    {
        return true;
    }
    auto v1 = getValue(expr->getLHS());
    auto v2 = getValue(expr->getRHS());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'A != false' (with A of"
                 " type %0) can %select{logically|literally}1 be simplified as"
                 " 'A'"),
                compat::getBeginLoc(expr))
                << expr->getLHS()->IgnoreImpCasts()->getType()
                << expr->getLHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::True:
            {
                auto e = getSubExprOfLogicalNegation(expr->getLHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("not-equal-to expression of the form 'A != true' (with"
                         " A of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getLHS()->IgnoreImpCasts()->getType()
                        << (expr->getLHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("not-equal-to expression of the form '!A != true'"
                         " (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'false != A' (with A of"
                 " type %0) can %select{logically|literally}1 be simplified as"
                 " 'A'"),
                compat::getBeginLoc(expr))
                << expr->getRHS()->IgnoreImpCasts()->getType()
                << expr->getRHS()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'false != false' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'false != true' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            {
                auto e = getSubExprOfLogicalNegation(expr->getRHS());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("not-equal-to expression of the form 'true != A' (with"
                         " A of type %0) can %select{logically|literally}1 be"
                         " simplified as '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getRHS()->IgnoreImpCasts()->getType()
                        << (expr->getRHS()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("not-equal-to expression of the form 'true != !A'"
                         " (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'true != false' can"
                 " literally be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("not-equal-to expression of the form 'true != true' can"
                 " literally be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::VisitConditionalOperator(ConditionalOperator const * expr) {
    if (ignoreLocation(expr)) {
        return true;
    }
    auto v1 = getValue(expr->getTrueExpr());
    auto v2 = getValue(expr->getFalseExpr());
    switch (v1) {
    case Value::Unknown:
        switch (v2) {
        case Value::Unknown:
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("conditional expression of the form 'A ? B : false' (with A of"
                 " type %0 and B of type %1) can %select{logically|literally}2"
                 " be simplified as 'A && B'"),
                compat::getBeginLoc(expr))
                << expr->getCond()->IgnoreImpCasts()->getType()
                << expr->getTrueExpr()->IgnoreImpCasts()->getType()
                << ((expr->getCond()->IgnoreImpCasts()->getType()
                     ->isBooleanType())
                    && (expr->getTrueExpr()->IgnoreImpCasts()->getType()
                        ->isBooleanType()))
                << expr->getSourceRange();
            break;
        case Value::True:
            {
                auto e = getSubExprOfLogicalNegation(expr->getCond());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form 'A ? B : true'"
                         " (with A of type %0 and B of type %1) can"
                         " %select{logically|literally}2 be simplified as '!A"
                         " || B'"),
                        compat::getBeginLoc(expr))
                        << expr->getCond()->IgnoreImpCasts()->getType()
                        << expr->getTrueExpr()->IgnoreImpCasts()->getType()
                        << ((expr->getCond()->IgnoreImpCasts()->getType()
                             ->isBooleanType())
                            && (expr->getTrueExpr()->IgnoreImpCasts()->getType()
                                ->isBooleanType()))
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form '!A ? B : true'"
                         " (with A of type %0 and B of type %1) can"
                         " %select{logically|literally}2 be simplified as 'A ||"
                         " B'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << expr->getTrueExpr()->IgnoreImpCasts()->getType()
                        << (e->IgnoreImpCasts()->getType()->isBooleanType()
                            && (expr->getTrueExpr()->IgnoreImpCasts()
                                ->getType()->isBooleanType()))
                        << expr->getSourceRange();
                }
                break;
            }
        }
        break;
    case Value::False:
        switch (v2) {
        case Value::Unknown:
            {
                auto e = getSubExprOfLogicalNegation(expr->getCond());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form 'A ? false : B'"
                         " (with A of type %0 and B of type %1) can"
                         " %select{logically|literally}2 be simplified as '!A"
                         " && B'"),
                        compat::getBeginLoc(expr))
                        << expr->getCond()->IgnoreImpCasts()->getType()
                        << expr->getFalseExpr()->IgnoreImpCasts()->getType()
                        << ((expr->getCond()->IgnoreImpCasts()->getType()
                             ->isBooleanType())
                            && (expr->getFalseExpr()->IgnoreImpCasts()
                                ->getType()->isBooleanType()))
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form '!A ? false : B'"
                         " (with A of type %0 and B of type %1) can"
                         " %select{logically|literally}2 be simplified as 'A &&"
                         " B'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << expr->getFalseExpr()->IgnoreImpCasts()->getType()
                        << (e->IgnoreImpCasts()->getType()->isBooleanType()
                            && (expr->getFalseExpr()->IgnoreImpCasts()
                                ->getType()->isBooleanType()))
                        << expr->getSourceRange();
                }
                break;
            }
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("conditional expression of the form 'A ? false : false' (with"
                 " A of type %0) can logically be simplified as 'false'"),
                compat::getBeginLoc(expr))
                << expr->getCond()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        case Value::True:
            {
                auto e = getSubExprOfLogicalNegation(expr->getCond());
                if (e == nullptr) {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form 'A ? false : true'"
                         " (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as"
                         " '!A'"),
                        compat::getBeginLoc(expr))
                        << expr->getCond()->IgnoreImpCasts()->getType()
                        << (expr->getCond()->IgnoreImpCasts()->getType()
                            ->isBooleanType())
                        << expr->getSourceRange();
                } else {
                    report(
                        DiagnosticsEngine::Warning,
                        ("conditional expression of the form '!A ? false :"
                         " true' (with A of type %0) can"
                         " %select{logically|literally}1 be simplified as 'A'"),
                        compat::getBeginLoc(expr))
                        << e->IgnoreImpCasts()->getType()
                        << e->IgnoreImpCasts()->getType()->isBooleanType()
                        << expr->getSourceRange();
                }
                break;
            }
        }
        break;
    case Value::True:
        switch (v2) {
        case Value::Unknown:
            report(
                DiagnosticsEngine::Warning,
                ("conditional expression of the form 'A ? true : B' (with A of"
                 " type %0 and B of type %1) can %select{logically|literally}2"
                 " be simplified as 'A || B'"),
                compat::getBeginLoc(expr))
                << expr->getCond()->IgnoreImpCasts()->getType()
                << expr->getFalseExpr()->IgnoreImpCasts()->getType()
                << ((expr->getCond()->IgnoreImpCasts()->getType()
                     ->isBooleanType())
                    && (expr->getFalseExpr()->IgnoreImpCasts()->getType()
                        ->isBooleanType()))
                << expr->getSourceRange();
            break;
        case Value::False:
            report(
                DiagnosticsEngine::Warning,
                ("conditional expression of the form 'A ? true : false' (with A"
                 " of type %0) can %select{logically|literally}1 be simplified"
                 " as 'A'"),
                compat::getBeginLoc(expr))
                << expr->getCond()->IgnoreImpCasts()->getType()
                << expr->getCond()->IgnoreImpCasts()->getType()->isBooleanType()
                << expr->getSourceRange();
            break;
        case Value::True:
            report(
                DiagnosticsEngine::Warning,
                ("conditional expression of the form 'A ? true : true' (with A"
                 " of type %0) can logically be simplified as 'true'"),
                compat::getBeginLoc(expr))
                << expr->getCond()->IgnoreImpCasts()->getType()
                << expr->getSourceRange();
            break;
        }
        break;
    }
    return true;
}

bool SimplifyBool::TraverseFunctionDecl(FunctionDecl * functionDecl) {
    auto copy = m_insideFunctionDecl;
    m_insideFunctionDecl = functionDecl;
    bool ret = RecursiveASTVisitor::TraverseFunctionDecl(functionDecl);
    m_insideFunctionDecl = copy;
    return ret;
}

bool SimplifyBool::TraverseCXXMethodDecl(CXXMethodDecl * functionDecl) {
    auto copy = m_insideFunctionDecl;
    m_insideFunctionDecl = functionDecl;
    bool ret = RecursiveASTVisitor::TraverseCXXMethodDecl(functionDecl);
    m_insideFunctionDecl = copy;
    return ret;
}

loplugin::Plugin::Registration<SimplifyBool> X("simplifybool");

}

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