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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 "plugin.hxx"
#include "check.hxx"
#include "compat.hxx"
#include "functionaddress.hxx"
#include <iostream>
#include <set>
#include <string>
/*
Look for member functions that merely return a compile-time constant, or they are empty, and can thus
be either removed, or converted into a constant.
This mostly tends to happen as a side-effect of other cleanups.
*/
namespace
{
class ReturnConstant : public loplugin::FunctionAddress<ReturnConstant>
{
public:
explicit ReturnConstant(loplugin::InstantiationData const& data)
: loplugin::FunctionAddress<ReturnConstant>(data)
{
}
void run() override
{
TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
for (auto& pair : problemFunctions)
{
auto functionDecl = pair.first;
auto canonicalDecl = functionDecl->getCanonicalDecl();
if (getFunctionsWithAddressTaken().find(canonicalDecl)
!= getFunctionsWithAddressTaken().end())
continue;
report(DiagnosticsEngine::Warning,
"Method only returns a single constant value %0, does it make sense?",
compat::getBeginLoc(functionDecl))
<< pair.second << functionDecl->getSourceRange();
if (functionDecl != functionDecl->getCanonicalDecl())
report(DiagnosticsEngine::Note, "decl here",
compat::getBeginLoc(functionDecl->getCanonicalDecl()))
<< functionDecl->getCanonicalDecl()->getSourceRange();
}
}
bool TraverseCXXMethodDecl(CXXMethodDecl*);
bool VisitReturnStmt(ReturnStmt const*);
private:
std::string getExprValue(Expr const* arg);
struct Context
{
bool ignore = false;
std::set<std::string> values;
};
std::vector<Context> m_functionStack;
std::vector<std::pair<FunctionDecl const*, std::string>> problemFunctions;
};
bool ReturnConstant::TraverseCXXMethodDecl(CXXMethodDecl* functionDecl)
{
if (ignoreLocation(functionDecl))
return true;
if (isInUnoIncludeFile(functionDecl))
return true;
if (!functionDecl->hasBody())
return true;
if (!functionDecl->isThisDeclarationADefinition())
return true;
if (functionDecl->isConstexpr())
return true;
if (functionDecl->getReturnType()->isVoidType())
return true;
if (functionDecl->isVirtual())
return true;
// static with inline body will be optimised at compile-time to a constant anyway
if (functionDecl->isStatic()
&& (functionDecl->hasInlineBody() || functionDecl->isInlineSpecified()))
return true;
// this catches some stuff in templates
if (functionDecl->hasAttr<OverrideAttr>())
return true;
// include/unotools/localedatawrapper.hxx
if (functionDecl->getIdentifier() && functionDecl->getName() == "getCurrZeroChar")
return true;
// sc/inc/stlalgorithm.hxx
if (loplugin::DeclCheck(functionDecl->getParent())
.Class("AlignedAllocator")
.Namespace("sc")
.GlobalNamespace())
return true;
switch (functionDecl->getOverloadedOperator())
{
case OO_Delete:
case OO_EqualEqual:
case OO_Call:
return true;
default:
break;
}
// gtk signals and slots stuff
if (loplugin::TypeCheck(functionDecl->getReturnType()).Typedef("gboolean"))
return true;
// ignore LINK macro stuff
std::string aImmediateMacro = "";
if (compiler.getSourceManager().isMacroBodyExpansion(compat::getBeginLoc(functionDecl))
|| compiler.getSourceManager().isMacroArgExpansion(compat::getBeginLoc(functionDecl)))
{
StringRef name{ Lexer::getImmediateMacroName(compat::getBeginLoc(functionDecl),
compiler.getSourceManager(),
compiler.getLangOpts()) };
aImmediateMacro = name;
if (name.find("IMPL_LINK") != StringRef::npos
|| name.find("IMPL_STATIC_LINK") != StringRef::npos
|| name.find("DECL_LINK") != StringRef::npos
|| name.find("SFX_IMPL_POS_CHILDWINDOW_WITHID") != StringRef::npos)
return true;
}
m_functionStack.emplace_back();
bool ret = RecursiveASTVisitor<ReturnConstant>::TraverseCXXMethodDecl(functionDecl);
Context& rContext = m_functionStack.back();
if (!rContext.ignore && rContext.values.size() == 1
&& rContext.values.find("unknown") == rContext.values.end())
{
problemFunctions.push_back({ functionDecl, *rContext.values.begin() });
}
m_functionStack.pop_back();
return ret;
}
bool ReturnConstant::VisitReturnStmt(ReturnStmt const* returnStmt)
{
if (ignoreLocation(returnStmt))
return true;
if (m_functionStack.empty())
return true;
Context& rContext = m_functionStack.back();
if (!returnStmt->getRetValue())
return true;
if (returnStmt->getRetValue()->isTypeDependent())
{
rContext.ignore = true;
return true;
}
if (const UnaryOperator* unaryOp = dyn_cast<UnaryOperator>(returnStmt->getRetValue()))
{
if (unaryOp->getOpcode() == UO_AddrOf)
{
rContext.ignore = true;
return true;
}
}
rContext.values.insert(getExprValue(returnStmt->getRetValue()));
return true;
}
std::string ReturnConstant::getExprValue(Expr const* 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 "unknown";
}
APSInt x1;
if (arg->EvaluateAsInt(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 && strippedArg->getSubExpr())
{
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 "unknown";
}
loplugin::Plugin::Registration<ReturnConstant> X("returnconstant", false);
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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