diff options
Diffstat (limited to 'compilerplugins/clang/constfields.cxx')
| -rw-r--r-- | compilerplugins/clang/constfields.cxx | 597 |
1 files changed, 597 insertions, 0 deletions
diff --git a/compilerplugins/clang/constfields.cxx b/compilerplugins/clang/constfields.cxx new file mode 100644 index 000000000..b06773c55 --- /dev/null +++ b/compilerplugins/clang/constfields.cxx @@ -0,0 +1,597 @@ +/* -*- 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/. + */ + +#if !defined _WIN32 //TODO, #include <sys/file.h> + +#include <cassert> +#include <string> +#include <iostream> +#include <fstream> +#include <unordered_set> +#include <vector> +#include <algorithm> +#include <sys/file.h> +#include <unistd.h> + +#include "config_clang.h" + +#include "plugin.hxx" +#include "compat.hxx" +#include "check.hxx" + +#if CLANG_VERSION >= 110000 +#include "clang/AST/ParentMapContext.h" +#endif + +/** +Look for fields that are only assigned to in the constructor using field-init, and can therefore be const. + +The process goes something like this: + $ make check + $ make FORCE_COMPILE_ALL=1 COMPILER_PLUGIN_TOOL='constfields' check + $ ./compilerplugins/clang/constfields.py + +and then + $ for dir in *; do make $dir FORCE_COMPILE_ALL=1 UPDATE_FILES=$dir COMPILER_PLUGIN_TOOL='constfieldsrewrite' $dir; done +to auto-remove the method declarations + +*/ + +namespace +{ +struct MyFieldInfo +{ + const RecordDecl* parentRecord; + std::string parentClass; + std::string fieldName; + std::string fieldType; + std::string sourceLocation; + std::string access; +}; +bool operator<(const MyFieldInfo& lhs, const MyFieldInfo& rhs) +{ + return std::tie(lhs.parentClass, lhs.fieldName) < std::tie(rhs.parentClass, rhs.fieldName); +} + +// try to limit the voluminous output a little +static std::set<MyFieldInfo> cannotBeConstSet; +static std::set<MyFieldInfo> definitionSet; + +/** + * Wrap the different kinds of callable and callee objects in the clang AST so I can define methods that handle everything. + */ +class CallerWrapper +{ + const CallExpr* m_callExpr; + const CXXConstructExpr* m_cxxConstructExpr; + +public: + CallerWrapper(const CallExpr* callExpr) + : m_callExpr(callExpr) + , m_cxxConstructExpr(nullptr) + { + } + CallerWrapper(const CXXConstructExpr* cxxConstructExpr) + : m_callExpr(nullptr) + , m_cxxConstructExpr(cxxConstructExpr) + { + } + unsigned getNumArgs() const + { + return m_callExpr ? m_callExpr->getNumArgs() : m_cxxConstructExpr->getNumArgs(); + } + const Expr* getArg(unsigned i) const + { + return m_callExpr ? m_callExpr->getArg(i) : m_cxxConstructExpr->getArg(i); + } +}; +class CalleeWrapper +{ + const FunctionDecl* m_calleeFunctionDecl = nullptr; + const CXXConstructorDecl* m_cxxConstructorDecl = nullptr; + const FunctionProtoType* m_functionPrototype = nullptr; + +public: + explicit CalleeWrapper(const FunctionDecl* calleeFunctionDecl) + : m_calleeFunctionDecl(calleeFunctionDecl) + { + } + explicit CalleeWrapper(const CXXConstructExpr* cxxConstructExpr) + : m_cxxConstructorDecl(cxxConstructExpr->getConstructor()) + { + } + explicit CalleeWrapper(const FunctionProtoType* functionPrototype) + : m_functionPrototype(functionPrototype) + { + } + unsigned getNumParams() const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getNumParams(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getNumParams(); + else if (m_functionPrototype->param_type_begin() == m_functionPrototype->param_type_end()) + // FunctionProtoType will assert if we call getParamTypes() and it has no params + return 0; + else + return m_functionPrototype->getParamTypes().size(); + } + const QualType getParamType(unsigned i) const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getParamDecl(i)->getType(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getParamDecl(i)->getType(); + else + return m_functionPrototype->getParamTypes()[i]; + } + std::string getNameAsString() const + { + if (m_calleeFunctionDecl) + return m_calleeFunctionDecl->getNameAsString(); + else if (m_cxxConstructorDecl) + return m_cxxConstructorDecl->getNameAsString(); + else + return ""; + } + CXXMethodDecl const* getAsCXXMethodDecl() const + { + if (m_calleeFunctionDecl) + return dyn_cast<CXXMethodDecl>(m_calleeFunctionDecl); + return nullptr; + } +}; + +class ConstFields : public RecursiveASTVisitor<ConstFields>, public loplugin::Plugin +{ +public: + explicit ConstFields(loplugin::InstantiationData const& data) + : Plugin(data) + { + } + + virtual void run() override; + + bool shouldVisitTemplateInstantiations() const { return true; } + bool shouldVisitImplicitCode() const { return true; } + + bool VisitFieldDecl(const FieldDecl*); + bool VisitMemberExpr(const MemberExpr*); + bool TraverseCXXConstructorDecl(CXXConstructorDecl*); + bool TraverseCXXMethodDecl(CXXMethodDecl*); + bool TraverseFunctionDecl(FunctionDecl*); + bool TraverseIfStmt(IfStmt*); + +private: + MyFieldInfo niceName(const FieldDecl*); + void check(const FieldDecl* fieldDecl, const Expr* memberExpr); + bool isSomeKindOfZero(const Expr* arg); + bool IsPassedByNonConst(const FieldDecl* fieldDecl, const Stmt* child, CallerWrapper callExpr, + CalleeWrapper calleeFunctionDecl); + llvm::Optional<CalleeWrapper> getCallee(CallExpr const*); + + RecordDecl* insideMoveOrCopyDeclParent = nullptr; + // For reasons I do not understand, parentFunctionDecl() is not reliable, so + // we store the parent function on the way down the AST. + FunctionDecl* insideFunctionDecl = nullptr; + std::vector<FieldDecl const*> insideConditionalCheckOfMemberSet; +}; + +void ConstFields::run() +{ + TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); + + if (!isUnitTestMode()) + { + // 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 MyFieldInfo& s : cannotBeConstSet) + output += "write-outside-constructor:\t" + s.parentClass + "\t" + s.fieldName + "\n"; + for (const MyFieldInfo& s : definitionSet) + output += "definition:\t" + s.access + "\t" + s.parentClass + "\t" + s.fieldName + "\t" + + s.fieldType + "\t" + s.sourceLocation + "\n"; + std::ofstream myfile; + myfile.open(WORKDIR "/loplugin.constfields.log", std::ios::app | std::ios::out); + myfile << output; + myfile.close(); + } + else + { + for (const MyFieldInfo& s : cannotBeConstSet) + report(DiagnosticsEngine::Warning, "notconst %0", compat::getBeginLoc(s.parentRecord)) + << s.fieldName; + } +} + +MyFieldInfo ConstFields::niceName(const FieldDecl* fieldDecl) +{ + MyFieldInfo aInfo; + + const RecordDecl* recordDecl = fieldDecl->getParent(); + + if (const CXXRecordDecl* cxxRecordDecl = dyn_cast<CXXRecordDecl>(recordDecl)) + { + if (cxxRecordDecl->getTemplateInstantiationPattern()) + cxxRecordDecl = cxxRecordDecl->getTemplateInstantiationPattern(); + aInfo.parentRecord = cxxRecordDecl; + aInfo.parentClass = cxxRecordDecl->getQualifiedNameAsString(); + } + else + { + aInfo.parentRecord = recordDecl; + aInfo.parentClass = recordDecl->getQualifiedNameAsString(); + } + + aInfo.fieldName = fieldDecl->getNameAsString(); + // sometimes the name (if it's an anonymous thing) contains the full path of the build folder, which we don't need + size_t idx = aInfo.fieldName.find(SRCDIR); + if (idx != std::string::npos) + { + aInfo.fieldName = aInfo.fieldName.replace(idx, strlen(SRCDIR), ""); + } + aInfo.fieldType = fieldDecl->getType().getAsString(); + + SourceLocation expansionLoc + = compiler.getSourceManager().getExpansionLoc(fieldDecl->getLocation()); + StringRef name = getFilenameOfLocation(expansionLoc); + aInfo.sourceLocation + = std::string(name.substr(strlen(SRCDIR) + 1)) + ":" + + std::to_string(compiler.getSourceManager().getSpellingLineNumber(expansionLoc)); + loplugin::normalizeDotDotInFilePath(aInfo.sourceLocation); + + switch (fieldDecl->getAccess()) + { + case AS_public: + aInfo.access = "public"; + break; + case AS_private: + aInfo.access = "private"; + break; + case AS_protected: + aInfo.access = "protected"; + break; + default: + aInfo.access = "unknown"; + break; + } + + return aInfo; +} + +bool ConstFields::VisitFieldDecl(const FieldDecl* fieldDecl) +{ + fieldDecl = fieldDecl->getCanonicalDecl(); + if (ignoreLocation(fieldDecl)) + { + return true; + } + // ignore stuff that forms part of the stable URE interface + if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(fieldDecl->getLocation()))) + { + return true; + } + definitionSet.insert(niceName(fieldDecl)); + return true; +} + +bool ConstFields::TraverseCXXConstructorDecl(CXXConstructorDecl* cxxConstructorDecl) +{ + auto copy = insideMoveOrCopyDeclParent; + if (!ignoreLocation(cxxConstructorDecl) && cxxConstructorDecl->isThisDeclarationADefinition()) + { + if (cxxConstructorDecl->isCopyOrMoveConstructor()) + insideMoveOrCopyDeclParent = cxxConstructorDecl->getParent(); + } + bool ret = RecursiveASTVisitor::TraverseCXXConstructorDecl(cxxConstructorDecl); + insideMoveOrCopyDeclParent = copy; + return ret; +} + +bool ConstFields::TraverseCXXMethodDecl(CXXMethodDecl* cxxMethodDecl) +{ + auto copy1 = insideMoveOrCopyDeclParent; + auto copy2 = insideFunctionDecl; + if (!ignoreLocation(cxxMethodDecl) && cxxMethodDecl->isThisDeclarationADefinition()) + { + if (cxxMethodDecl->isCopyAssignmentOperator() || cxxMethodDecl->isMoveAssignmentOperator()) + insideMoveOrCopyDeclParent = cxxMethodDecl->getParent(); + } + insideFunctionDecl = cxxMethodDecl; + bool ret = RecursiveASTVisitor::TraverseCXXMethodDecl(cxxMethodDecl); + insideMoveOrCopyDeclParent = copy1; + insideFunctionDecl = copy2; + return ret; +} + +bool ConstFields::TraverseFunctionDecl(FunctionDecl* functionDecl) +{ + auto copy2 = insideFunctionDecl; + insideFunctionDecl = functionDecl; + bool ret = RecursiveASTVisitor::TraverseFunctionDecl(functionDecl); + insideFunctionDecl = copy2; + return ret; +} + +bool ConstFields::TraverseIfStmt(IfStmt* ifStmt) +{ + FieldDecl const* memberFieldDecl = nullptr; + Expr const* cond = ifStmt->getCond()->IgnoreParenImpCasts(); + if (auto memberExpr = dyn_cast<MemberExpr>(cond)) + { + if ((memberFieldDecl = dyn_cast<FieldDecl>(memberExpr->getMemberDecl()))) + insideConditionalCheckOfMemberSet.push_back(memberFieldDecl); + } + bool ret = RecursiveASTVisitor::TraverseIfStmt(ifStmt); + if (memberFieldDecl) + insideConditionalCheckOfMemberSet.pop_back(); + return ret; +} + +bool ConstFields::VisitMemberExpr(const MemberExpr* memberExpr) +{ + const ValueDecl* decl = memberExpr->getMemberDecl(); + const FieldDecl* fieldDecl = dyn_cast<FieldDecl>(decl); + if (!fieldDecl) + { + return true; + } + fieldDecl = fieldDecl->getCanonicalDecl(); + if (ignoreLocation(fieldDecl)) + { + return true; + } + // ignore stuff that forms part of the stable URE interface + if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(fieldDecl->getLocation()))) + { + return true; + } + + check(fieldDecl, memberExpr); + + return true; +} + +void ConstFields::check(const FieldDecl* fieldDecl, const Expr* memberExpr) +{ + auto parentsRange = getParents(*memberExpr); + const Stmt* child = memberExpr; + const Stmt* parent + = parentsRange.begin() == parentsRange.end() ? nullptr : parentsRange.begin()->get<Stmt>(); + // walk up the tree until we find something interesting + bool bCannotBeConst = false; + bool bDump = false; + auto walkUp = [&]() { + child = parent; + auto parentsRange = getParents(*parent); + parent = parentsRange.begin() == parentsRange.end() ? nullptr + : parentsRange.begin()->get<Stmt>(); + }; + do + { + if (!parent) + { + // check if we have an expression like + // int& r = m_field; + auto parentsRange = getParents(*child); + if (parentsRange.begin() != parentsRange.end()) + { + auto varDecl = dyn_cast_or_null<VarDecl>(parentsRange.begin()->get<Decl>()); + // The isImplicit() call is to avoid triggering when we see the vardecl which is part of a for-range statement, + // which is of type 'T&&' and also an l-value-ref ? + if (varDecl && !varDecl->isImplicit() + && loplugin::TypeCheck(varDecl->getType()).LvalueReference().NonConst()) + { + bCannotBeConst = true; + } + } + break; + } + if (isa<CXXReinterpretCastExpr>(parent)) + { + // once we see one of these, there is not much useful we can know + bCannotBeConst = true; + break; + } + else if (isa<CastExpr>(parent) || isa<MemberExpr>(parent) || isa<ParenExpr>(parent) + || isa<ParenListExpr>(parent) || isa<ArrayInitLoopExpr>(parent) + || isa<ExprWithCleanups>(parent)) + { + walkUp(); + } + else if (auto unaryOperator = dyn_cast<UnaryOperator>(parent)) + { + UnaryOperator::Opcode op = unaryOperator->getOpcode(); + if (op == UO_AddrOf || op == UO_PostInc || op == UO_PostDec || op == UO_PreInc + || op == UO_PreDec) + { + bCannotBeConst = true; + } + walkUp(); + } + else if (auto operatorCallExpr = dyn_cast<CXXOperatorCallExpr>(parent)) + { + auto callee = getCallee(operatorCallExpr); + if (callee) + { + // if calling a non-const operator on the field + auto calleeMethodDecl = callee->getAsCXXMethodDecl(); + if (calleeMethodDecl && operatorCallExpr->getArg(0) == child + && !calleeMethodDecl->isConst()) + { + bCannotBeConst = true; + } + else if (IsPassedByNonConst(fieldDecl, child, operatorCallExpr, *callee)) + { + bCannotBeConst = true; + } + } + else + bCannotBeConst = true; // conservative, could improve + walkUp(); + } + else if (auto cxxMemberCallExpr = dyn_cast<CXXMemberCallExpr>(parent)) + { + const CXXMethodDecl* calleeMethodDecl = cxxMemberCallExpr->getMethodDecl(); + if (calleeMethodDecl) + { + // if calling a non-const method on the field + const Expr* tmp = dyn_cast<Expr>(child); + if (tmp->isBoundMemberFunction(compiler.getASTContext())) + { + tmp = dyn_cast<MemberExpr>(tmp)->getBase(); + } + if (cxxMemberCallExpr->getImplicitObjectArgument() == tmp + && !calleeMethodDecl->isConst()) + { + bCannotBeConst = true; + break; + } + if (IsPassedByNonConst(fieldDecl, child, cxxMemberCallExpr, + CalleeWrapper(calleeMethodDecl))) + bCannotBeConst = true; + } + else + bCannotBeConst = true; // can happen in templates + walkUp(); + } + else if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(parent)) + { + if (IsPassedByNonConst(fieldDecl, child, cxxConstructExpr, + CalleeWrapper(cxxConstructExpr))) + bCannotBeConst = true; + walkUp(); + } + else if (auto callExpr = dyn_cast<CallExpr>(parent)) + { + auto callee = getCallee(callExpr); + if (callee) + { + if (IsPassedByNonConst(fieldDecl, child, callExpr, *callee)) + bCannotBeConst = true; + } + else + bCannotBeConst = true; // conservative, could improve + walkUp(); + } + else if (auto binaryOp = dyn_cast<BinaryOperator>(parent)) + { + BinaryOperator::Opcode op = binaryOp->getOpcode(); + const bool assignmentOp = op == BO_Assign || 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; + if (assignmentOp) + { + if (binaryOp->getLHS() == child) + bCannotBeConst = true; + else if (loplugin::TypeCheck(binaryOp->getLHS()->getType()) + .LvalueReference() + .NonConst()) + // if the LHS is a non-const reference, we could write to the field later on + bCannotBeConst = true; + } + walkUp(); + } + else if (isa<ReturnStmt>(parent)) + { + if (insideFunctionDecl) + { + auto tc = loplugin::TypeCheck(insideFunctionDecl->getReturnType()); + if (tc.LvalueReference().NonConst()) + bCannotBeConst = true; + } + break; + } + else if (isa<SwitchStmt>(parent) || isa<WhileStmt>(parent) || isa<ForStmt>(parent) + || isa<IfStmt>(parent) || isa<DoStmt>(parent) || isa<CXXForRangeStmt>(parent) + || isa<DefaultStmt>(parent)) + { + break; + } + else + { + walkUp(); + } + } while (true); + + if (bDump) + { + report(DiagnosticsEngine::Warning, "oh dear, what can the matter be? writtenTo=%0", + compat::getBeginLoc(memberExpr)) + << bCannotBeConst << memberExpr->getSourceRange(); + if (parent) + { + report(DiagnosticsEngine::Note, "parent over here", compat::getBeginLoc(parent)) + << parent->getSourceRange(); + parent->dump(); + } + memberExpr->dump(); + fieldDecl->getType()->dump(); + } + + if (bCannotBeConst) + { + cannotBeConstSet.insert(niceName(fieldDecl)); + } +} + +bool ConstFields::IsPassedByNonConst(const FieldDecl* fieldDecl, const Stmt* child, + CallerWrapper callExpr, CalleeWrapper calleeFunctionDecl) +{ + unsigned len = std::min(callExpr.getNumArgs(), calleeFunctionDecl.getNumParams()); + // if it's an array, passing it by value to a method typically means the + // callee takes a pointer and can modify the array + if (fieldDecl->getType()->isConstantArrayType()) + { + for (unsigned i = 0; i < len; ++i) + if (callExpr.getArg(i) == child) + if (loplugin::TypeCheck(calleeFunctionDecl.getParamType(i)).Pointer().NonConst()) + return true; + } + else + { + for (unsigned i = 0; i < len; ++i) + if (callExpr.getArg(i) == child) + if (loplugin::TypeCheck(calleeFunctionDecl.getParamType(i)) + .LvalueReference() + .NonConst()) + return true; + } + return false; +} + +llvm::Optional<CalleeWrapper> ConstFields::getCallee(CallExpr const* callExpr) +{ + FunctionDecl const* functionDecl = callExpr->getDirectCallee(); + if (functionDecl) + return CalleeWrapper(functionDecl); + + // Extract the functionprototype from a type + clang::Type const* calleeType = callExpr->getCallee()->getType().getTypePtr(); + if (auto pointerType = calleeType->getUnqualifiedDesugaredType()->getAs<clang::PointerType>()) + { + if (auto prototype = pointerType->getPointeeType() + ->getUnqualifiedDesugaredType() + ->getAs<FunctionProtoType>()) + { + return CalleeWrapper(prototype); + } + } + + return llvm::Optional<CalleeWrapper>(); +} + +loplugin::Plugin::Registration<ConstFields> X("constfields", false); +} + +#endif + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |