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518 | /* -*- 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 <algorithm>
#include <string>
#include <unordered_set>
#include <unordered_map>
#include <iostream>
#include "config_clang.h"
#include "plugin.hxx"
#include "compat.hxx"
#include "check.hxx"
#include "functionaddress.hxx"
#if CLANG_VERSION >= 110000
#include "clang/AST/ParentMapContext.h"
#endif
/**
Find methods that can be declared const.
This analysis attempts to implement "logical const" as opposed to "technical const", which means
we ignore always-const nature of std::unique_ptr::operator->
This is not a sophisticated analysis. It deliberately skips all of the hard cases for now.
It is an exercise in getting the most benefit for the least effort.
*/
namespace
{
class ConstMethod:
public loplugin::FunctionAddress<loplugin::FilteringPlugin<ConstMethod>>
{
public:
explicit ConstMethod(loplugin::InstantiationData const & data): FunctionAddress(data) {}<--- Member variable 'ConstMethod::currCXXMethodDecl' is not initialized in the constructor.
virtual void run() override {
TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
for (const CXXMethodDecl *pMethodDecl : interestingMethodSet) {
if (methodCannotBeConstSet.find(pMethodDecl) != methodCannotBeConstSet.end())
continue;
auto canonicalDecl = pMethodDecl->getCanonicalDecl();
if (getFunctionsWithAddressTaken().find((FunctionDecl const *)canonicalDecl)
!= getFunctionsWithAddressTaken().end())
continue;
StringRef aFileName = getFilenameOfLocation(compiler.getSourceManager().getSpellingLoc(compat::getBeginLoc(canonicalDecl)));
if (loplugin::isSamePathname(aFileName, SRCDIR "/include/LibreOfficeKit/LibreOfficeKit.hxx"))
continue;
report(
DiagnosticsEngine::Warning,
"this method can be const",
compat::getBeginLoc(pMethodDecl))
<< pMethodDecl->getSourceRange();
if (canonicalDecl->getLocation() != pMethodDecl->getLocation()) {
report(
DiagnosticsEngine::Note,
"canonical method declaration here",
compat::getBeginLoc(canonicalDecl))
<< canonicalDecl->getSourceRange();
}
}
}
bool TraverseCXXMethodDecl(CXXMethodDecl *);
bool TraverseCXXConversionDecl(CXXConversionDecl *);
bool VisitCXXMethodDecl(const CXXMethodDecl *);
bool VisitCXXThisExpr(const CXXThisExpr *);
private:
bool isPointerOrReferenceToConst(const QualType& qt);
bool isPointerOrReferenceToNonConst(const QualType& qt);
bool checkIfCanBeConst(const Stmt*, const CXXMethodDecl*);
std::unordered_set<const CXXMethodDecl*> interestingMethodSet;
std::unordered_set<const CXXMethodDecl*> methodCannotBeConstSet;
CXXMethodDecl const * currCXXMethodDecl;
};
bool ConstMethod::TraverseCXXMethodDecl(CXXMethodDecl * cxxMethodDecl)
{
currCXXMethodDecl = cxxMethodDecl;
bool rv = RecursiveASTVisitor<ConstMethod>::TraverseCXXMethodDecl(cxxMethodDecl);
currCXXMethodDecl = nullptr;
return rv;
}
bool ConstMethod::TraverseCXXConversionDecl(CXXConversionDecl * cxxConversionDecl)
{
currCXXMethodDecl = cxxConversionDecl;
bool rv = RecursiveASTVisitor<ConstMethod>::TraverseCXXConversionDecl(cxxConversionDecl);
currCXXMethodDecl = nullptr;
return rv;
}
bool ConstMethod::VisitCXXMethodDecl(const CXXMethodDecl * cxxMethodDecl)<--- The function 'VisitCXXMethodDecl' is never used.
{
if (ignoreLocation(cxxMethodDecl) || !cxxMethodDecl->isThisDeclarationADefinition()) {
return true;
}
if (cxxMethodDecl->isConst())
return true;
// ignore stuff that forms part of the stable URE interface
if (isInUnoIncludeFile(cxxMethodDecl)) {
return true;
}
// TODO ignore template stuff for now
if (cxxMethodDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate) {
return true;
}
if (cxxMethodDecl->isDeleted())
return true;
if (cxxMethodDecl->isStatic())
return true;
if (cxxMethodDecl->isOverloadedOperator())
return true;
if (isa<CXXConstructorDecl>(cxxMethodDecl))
return true;
if (isa<CXXDestructorDecl>(cxxMethodDecl))
return true;
if (cxxMethodDecl->getParent()->getDescribedClassTemplate() != nullptr ) {
return true;
}
// ignore virtual methods
if (cxxMethodDecl->isVirtual() ) {
return true;
}
// ignore macro expansions so we can ignore the IMPL_LINK macros from include/tools/link.hxx
// TODO make this more precise
if (cxxMethodDecl->getLocation().isMacroID())
return true;
if (!cxxMethodDecl->getIdentifier())
return true;
if (cxxMethodDecl->getNumParams() > 0)
return true;
// returning pointers or refs to non-const stuff, and then having the whole method
// be const doesn't seem like a good idea
auto tc = loplugin::TypeCheck(cxxMethodDecl->getReturnType());
if (tc.Pointer().NonConst())
return true;
if (tc.LvalueReference().NonConst())
return true;
// a Get method that returns void is probably doing something that has side-effects
if (tc.Void())
return true;
StringRef name = cxxMethodDecl->getName();
if (!name.startswith("get") && !name.startswith("Get")
&& !name.startswith("is") && !name.startswith("Is")
&& !name.startswith("has") && !name.startswith("Has"))
return true;
// something lacking in my analysis here
if (loplugin::DeclCheck(cxxMethodDecl).Function("GetDescr").Class("SwRangeRedline").GlobalNamespace())
return true;
interestingMethodSet.insert(cxxMethodDecl);
return true;
}
bool ConstMethod::VisitCXXThisExpr( const CXXThisExpr* cxxThisExpr )<--- The function 'VisitCXXThisExpr' is never used.
{
if (!currCXXMethodDecl)
return true;
if (ignoreLocation(cxxThisExpr))
return true;
// ignore stuff that forms part of the stable URE interface
if (isInUnoIncludeFile(compat::getBeginLoc(cxxThisExpr)))
return true;
if (interestingMethodSet.find(currCXXMethodDecl) == interestingMethodSet.end())
return true;
// no need to check again if we have already eliminated this one
if (methodCannotBeConstSet.find(currCXXMethodDecl) != methodCannotBeConstSet.end())
return true;
if (!checkIfCanBeConst(cxxThisExpr, currCXXMethodDecl))
methodCannotBeConstSet.insert(currCXXMethodDecl);
return true;
}
// Walk up from a statement that contains a CXXThisExpr, checking if the usage means that the
// related CXXMethodDecl can be const.
bool ConstMethod::checkIfCanBeConst(const Stmt* stmt, const CXXMethodDecl* cxxMethodDecl)
{
const Stmt* parent = getParentStmt( stmt );
if (!parent) {
auto parentsRange = getParents(*stmt);
if ( parentsRange.begin() == parentsRange.end())
return true;
auto varDecl = dyn_cast_or_null<VarDecl>(parentsRange.begin()->get<Decl>());
if (!varDecl)
{
report(
DiagnosticsEngine::Warning,
"no parent?",
compat::getBeginLoc(stmt))
<< stmt->getSourceRange();
return false;
}
return varDecl->getType()->isIntegralOrEnumerationType()
|| loplugin::TypeCheck(varDecl->getType()).Pointer().Const()
|| loplugin::TypeCheck(varDecl->getType()).LvalueReference().Const();
}
if (auto unaryOperator = dyn_cast<UnaryOperator>(parent)) {
UnaryOperator::Opcode op = unaryOperator->getOpcode();
if (op == UO_AddrOf || op == UO_PreInc || op == UO_PostInc
|| op == UO_PreDec || op == UO_PostDec) {
return false;
}
if (op == UO_Deref) {
return checkIfCanBeConst(parent, cxxMethodDecl);
}
return true;
} else if (auto binaryOp = dyn_cast<BinaryOperator>(parent)) {
BinaryOperator::Opcode op = binaryOp->getOpcode();
if (binaryOp->getRHS() == stmt) {
return true;
}
if (op == BO_Assign || op == BO_PtrMemD || op == BO_PtrMemI || op == BO_MulAssign
|| op == BO_DivAssign || op == BO_RemAssign || op == BO_AddAssign
|| op == BO_SubAssign || op == BO_ShlAssign || op == BO_ShrAssign
|| op == BO_AndAssign || op == BO_XorAssign || op == BO_OrAssign) {
return false;
}
// // for pointer arithmetic need to check parent
// if (binaryOp->getType()->isPointerType()) {
// return checkIfCanBeConst(parent, cxxMethodDecl);
// }
return true;
} else if (auto constructExpr = dyn_cast<CXXConstructExpr>(parent)) {
const CXXConstructorDecl * constructorDecl = constructExpr->getConstructor();
for (unsigned i = 0; i < constructExpr->getNumArgs(); ++i) {
if (constructExpr->getArg(i) == stmt) {
return isPointerOrReferenceToConst(constructorDecl->getParamDecl(i)->getType());
}
}
return false; // TODO ??
} else if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(parent)) {
const CXXMethodDecl* calleeMethodDecl = dyn_cast_or_null<CXXMethodDecl>(operatorCallExpr->getDirectCallee());
if (calleeMethodDecl) {
// unary operator
if (calleeMethodDecl->getNumParams() == 0) {
// some classes like std::unique_ptr do not do a very good job with their operator-> which is always const
if (operatorCallExpr->getOperator() == OO_Arrow || operatorCallExpr->getOperator() == OO_Star) {
return checkIfCanBeConst(parent, cxxMethodDecl);
}
return calleeMethodDecl->isConst();
}
// some classes like std::unique_ptr do not do a very good job with their operator[] which is always const
if (calleeMethodDecl->getNumParams() == 1 && operatorCallExpr->getArg(0) == stmt) {
if (operatorCallExpr->getOperator() == OO_Subscript) {
return false;
}
}
// binary operator
if (operatorCallExpr->getArg(0) == stmt) {
return calleeMethodDecl->isConst();
}
unsigned const n = std::min(
operatorCallExpr->getNumArgs(),
calleeMethodDecl->getNumParams());
for (unsigned i = 1; i < n; ++i)
if (operatorCallExpr->getArg(i) == stmt) {
return isPointerOrReferenceToConst(calleeMethodDecl->getParamDecl(i - 1)->getType());
}
} else {
const Expr* callee = operatorCallExpr->getCallee()->IgnoreParenImpCasts();
const DeclRefExpr* dr = dyn_cast<DeclRefExpr>(callee);
const FunctionDecl* calleeFunctionDecl = nullptr;
if (dr) {
calleeFunctionDecl = dyn_cast<FunctionDecl>(dr->getDecl());
}
if (calleeFunctionDecl) {
for (unsigned i = 0; i < operatorCallExpr->getNumArgs(); ++i) {
if (operatorCallExpr->getArg(i) == stmt) {
return isPointerOrReferenceToConst(calleeFunctionDecl->getParamDecl(i)->getType());
}
}
}
}
return false; // TODO ???
} else if (auto callExpr = dyn_cast<CallExpr>(parent)) {
QualType functionType = callExpr->getCallee()->getType();
if (functionType->isFunctionPointerType()) {
functionType = functionType->getPointeeType();
}
if (const FunctionProtoType* prototype = functionType->getAs<FunctionProtoType>()) {
// TODO could do better
if (prototype->isVariadic()) {
return false;
}
if (callExpr->getCallee() == stmt) {
return true;
}
for (unsigned i = 0; i < callExpr->getNumArgs(); ++i) {
if (callExpr->getArg(i) == stmt) {
return isPointerOrReferenceToConst(prototype->getParamType(i));
}
}
}
const FunctionDecl* calleeFunctionDecl = callExpr->getDirectCallee();
if (calleeFunctionDecl)
{
if (auto memberCallExpr = dyn_cast<CXXMemberCallExpr>(parent)) {
const MemberExpr* memberExpr = dyn_cast<MemberExpr>(stmt);
if (memberExpr && memberCallExpr->getImplicitObjectArgument() == memberExpr->getBase())
{
const CXXMethodDecl* calleeMethodDecl = dyn_cast<CXXMethodDecl>(calleeFunctionDecl);
// some classes like std::unique_ptr do not do a very good job with their get() which is always const
if (calleeMethodDecl->getIdentifier() && calleeMethodDecl->getName() == "get") {
return checkIfCanBeConst(parent, cxxMethodDecl);
}
// VclPtr<T>'s implicit conversion to T*
if (isa<CXXConversionDecl>(calleeMethodDecl)) {
if (loplugin::DeclCheck(calleeMethodDecl->getParent()).Class("OWeakObject").Namespace("cppu").GlobalNamespace())
return false;
return checkIfCanBeConst(parent, cxxMethodDecl);
}
return calleeMethodDecl->isConst();
}
}
// TODO could do better
if (calleeFunctionDecl->isVariadic()) {
return false;
}
if (callExpr->getCallee() == stmt) {
return true;
}
for (unsigned i = 0; i < callExpr->getNumArgs(); ++i) {
if (i >= calleeFunctionDecl->getNumParams()) // can happen in template code
return false;
if (callExpr->getArg(i) == stmt) {
return isPointerOrReferenceToConst(calleeFunctionDecl->getParamDecl(i)->getType());
}
}
}
return false; // TODO ????
// } else if (auto callExpr = dyn_cast<ObjCMessageExpr>(parent)) {
// if (callExpr->getInstanceReceiver() == stmt) {
// return true;
// }
// if (auto const method = callExpr->getMethodDecl()) {
// // TODO could do better
// if (method->isVariadic()) {
// return false;
// }
// assert(method->param_size() == callExpr->getNumArgs());
// for (unsigned i = 0; i < callExpr->getNumArgs(); ++i) {
// if (callExpr->getArg(i) == stmt) {
// return isPointerOrReferenceToConst(
// method->param_begin()[i]->getType());
// }
// }
// }
// return false; // TODO ????
} else if (isa<CXXReinterpretCastExpr>(parent)) {
return false;
} else if (isa<ImplicitCastExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<CXXStaticCastExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<CXXDynamicCastExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<CXXFunctionalCastExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<CXXConstCastExpr>(parent)) {
return false;
} else if (isa<CStyleCastExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
// } else if (isa<CastExpr>(parent)) { // all other cast expression subtypes
// if (auto e = dyn_cast<ExplicitCastExpr>(parent)) {
// if (loplugin::TypeCheck(e->getTypeAsWritten()).Void()) {
// if (auto const sub = dyn_cast<DeclRefExpr>(
// e->getSubExpr()->IgnoreParenImpCasts()))
// {
// if (sub->getDecl() == cxxMethodDecl) {
// return false;
// }
// }
// }
// }
// return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<MemberExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (auto arraySubscriptExpr = dyn_cast<ArraySubscriptExpr>(parent)) {
if (arraySubscriptExpr->getIdx() == stmt)
return true;
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<ParenExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (auto declStmt = dyn_cast<DeclStmt>(parent)) {
for (Decl const * decl : declStmt->decls())
if (auto varDecl = dyn_cast<VarDecl>(decl)) {
if (varDecl->getInit() == stmt) {
auto tc = loplugin::TypeCheck(varDecl->getType());
if (tc.LvalueReference() && !tc.LvalueReference().Const())
return false;
if (tc.Pointer() && !tc.Pointer().Const())
return false;
return true;
}
}
// fall through
} else if (isa<ReturnStmt>(parent)) {
return !isPointerOrReferenceToNonConst(cxxMethodDecl->getReturnType());
} else if (isa<InitListExpr>(parent)) {
return false; // TODO could be improved
} else if (isa<IfStmt>(parent)) {
return true;
} else if (isa<WhileStmt>(parent)) {
return true;
} else if (isa<ForStmt>(parent)) {
return true;
} else if (isa<CompoundStmt>(parent)) {
return true;
} else if (isa<SwitchStmt>(parent)) {
return true;
} else if (isa<DoStmt>(parent)) {
return true;
} else if (isa<CXXDeleteExpr>(parent)) {
return false;
// } else if (isa<VAArgExpr>(parent)) {
// return false;
} else if (isa<CXXDependentScopeMemberExpr>(parent)) {
return false;
} else if (isa<MaterializeTemporaryExpr>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (auto conditionalExpr = dyn_cast<ConditionalOperator>(parent)) {
if (conditionalExpr->getCond() == stmt)
return true;
return checkIfCanBeConst(parent, cxxMethodDecl);
// } else if (isa<UnaryExprOrTypeTraitExpr>(parent)) {
// return false; // ???
} else if (isa<CXXNewExpr>(parent)) {
// for (auto pa : cxxNewExpr->placement_arguments())
// if (pa == stmt)
// return false;
return true; // because the Stmt must be a parameter to the expression, probably an array length
// } else if (auto lambdaExpr = dyn_cast<LambdaExpr>(parent)) {
//// for (auto it = lambdaExpr->capture_begin(); it != lambdaExpr->capture_end(); ++it)
//// {
//// if (it->capturesVariable() && it->getCapturedVar() == cxxMethodDecl)
//// return it->getCaptureKind() != LCK_ByRef;
//// }
// return true;
// } else if (isa<CXXTypeidExpr>(parent)) {
// return true;
} else if (isa<ParenListExpr>(parent)) {
return true;
} else if (isa<CXXUnresolvedConstructExpr>(parent)) {
return false;
// } else if (isa<UnresolvedMemberExpr>(parent)) {
// return false;
// } else if (isa<PackExpansionExpr>(parent)) {
// return false;
} else if (isa<ExprWithCleanups>(parent)) {
return checkIfCanBeConst(parent, cxxMethodDecl);
// } else if (isa<CaseStmt>(parent)) {
// return true;
// } else if (isa<CXXPseudoDestructorExpr>(parent)) {
// return false;
// } else if (isa<CXXDependentScopeMemberExpr>(parent)) {
// return false;
// } else if (isa<ObjCIvarRefExpr>(parent)) {
// return checkIfCanBeConst(parent, cxxMethodDecl);
} else if (isa<CXXTemporaryObjectExpr>(parent)) {
return true;
} else if (isa<CXXBindTemporaryExpr>(parent)) {
return true;
}
if (parent)
parent->dump();
// if (cxxMethodDecl)
// cxxMethodDecl->dump();
report(
DiagnosticsEngine::Warning,
"oh dear, what can the matter be?",
compat::getBeginLoc(parent))
<< parent->getSourceRange();
return false;
}
bool ConstMethod::isPointerOrReferenceToConst(const QualType& qt) {
auto const type = loplugin::TypeCheck(qt);
if (type.Pointer()) {
return bool(type.Pointer().Const());
} else if (type.LvalueReference()) {
return bool(type.LvalueReference().Const());
}
return false;
}
bool ConstMethod::isPointerOrReferenceToNonConst(const QualType& qt) {
auto const type = loplugin::TypeCheck(qt);
if (type.Pointer()) {
return !bool(type.Pointer().Const());
} else if (type.LvalueReference()) {
return !bool(type.LvalueReference().Const());
}
return false;
}
loplugin::Plugin::Registration< ConstMethod > X("constmethod", false);
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
|