157 lines
6 KiB
C++
157 lines
6 KiB
C++
//===--- MultipleNewInOneExpressionCheck.cpp - clang-tidy------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "MultipleNewInOneExpressionCheck.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Lex/Lexer.h"
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using namespace clang::ast_matchers;
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namespace clang::tidy::bugprone {
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namespace {
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// Determine if the result of an expression is "stored" in some way.
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// It is true if the value is stored into a variable or used as initialization
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// or passed to a function or constructor.
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// For this use case compound assignments are not counted as a "store" (the 'E'
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// expression should have pointer type).
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bool isExprValueStored(const Expr *E, ASTContext &C) {
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E = E->IgnoreParenCasts();
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// Get first non-paren, non-cast parent.
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ParentMapContext &PMap = C.getParentMapContext();
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DynTypedNodeList P = PMap.getParents(*E);
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if (P.size() != 1)
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return false;
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const Expr *ParentE = nullptr;
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while ((ParentE = P[0].get<Expr>()) && ParentE->IgnoreParenCasts() == E) {
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P = PMap.getParents(P[0]);
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if (P.size() != 1)
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return false;
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}
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if (const auto *ParentVarD = P[0].get<VarDecl>())
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return ParentVarD->getInit()->IgnoreParenCasts() == E;
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if (!ParentE)
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return false;
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if (const auto *BinOp = dyn_cast<BinaryOperator>(ParentE))
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return BinOp->getOpcode() == BO_Assign &&
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BinOp->getRHS()->IgnoreParenCasts() == E;
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return isa<CallExpr, CXXConstructExpr>(ParentE);
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}
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} // namespace
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AST_MATCHER_P(CXXTryStmt, hasHandlerFor,
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ast_matchers::internal::Matcher<QualType>, InnerMatcher) {
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for (unsigned NH = Node.getNumHandlers(), I = 0; I < NH; ++I) {
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const CXXCatchStmt *CatchS = Node.getHandler(I);
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// Check for generic catch handler (match anything).
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if (CatchS->getCaughtType().isNull())
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return true;
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ast_matchers::internal::BoundNodesTreeBuilder Result(*Builder);
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if (InnerMatcher.matches(CatchS->getCaughtType(), Finder, &Result)) {
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*Builder = std::move(Result);
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return true;
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}
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}
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return false;
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}
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AST_MATCHER(CXXNewExpr, mayThrow) {
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FunctionDecl *OperatorNew = Node.getOperatorNew();
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if (!OperatorNew)
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return false;
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return !OperatorNew->getType()->castAs<FunctionProtoType>()->isNothrow();
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}
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void MultipleNewInOneExpressionCheck::registerMatchers(MatchFinder *Finder) {
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auto BadAllocType =
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recordType(hasDeclaration(cxxRecordDecl(hasName("::std::bad_alloc"))));
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auto ExceptionType =
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recordType(hasDeclaration(cxxRecordDecl(hasName("::std::exception"))));
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auto BadAllocReferenceType = referenceType(pointee(BadAllocType));
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auto ExceptionReferenceType = referenceType(pointee(ExceptionType));
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auto CatchBadAllocType =
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qualType(hasCanonicalType(anyOf(BadAllocType, BadAllocReferenceType,
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ExceptionType, ExceptionReferenceType)));
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auto BadAllocCatchingTryBlock = cxxTryStmt(hasHandlerFor(CatchBadAllocType));
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auto NewExprMayThrow = cxxNewExpr(mayThrow());
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auto HasNewExpr1 = expr(anyOf(NewExprMayThrow.bind("new1"),
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hasDescendant(NewExprMayThrow.bind("new1"))));
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auto HasNewExpr2 = expr(anyOf(NewExprMayThrow.bind("new2"),
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hasDescendant(NewExprMayThrow.bind("new2"))));
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Finder->addMatcher(
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callExpr(
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hasAnyArgument(
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expr(HasNewExpr1).bind("arg1")),
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hasAnyArgument(
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expr(HasNewExpr2, unless(equalsBoundNode("arg1"))).bind("arg2")),
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hasAncestor(BadAllocCatchingTryBlock)),
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this);
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Finder->addMatcher(
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cxxConstructExpr(
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hasAnyArgument(
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expr(HasNewExpr1).bind("arg1")),
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hasAnyArgument(
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expr(HasNewExpr2, unless(equalsBoundNode("arg1"))).bind("arg2")),
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unless(isListInitialization()),
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hasAncestor(BadAllocCatchingTryBlock)),
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this);
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Finder->addMatcher(binaryOperator(hasLHS(HasNewExpr1), hasRHS(HasNewExpr2),
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unless(hasAnyOperatorName("&&", "||", ",")),
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hasAncestor(BadAllocCatchingTryBlock)),
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this);
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Finder->addMatcher(
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cxxNewExpr(mayThrow(),
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hasDescendant(NewExprMayThrow.bind("new2_in_new1")),
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hasAncestor(BadAllocCatchingTryBlock))
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.bind("new1"),
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this);
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}
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void MultipleNewInOneExpressionCheck::check(
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const MatchFinder::MatchResult &Result) {
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const auto *NewExpr1 = Result.Nodes.getNodeAs<CXXNewExpr>("new1");
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const auto *NewExpr2 = Result.Nodes.getNodeAs<CXXNewExpr>("new2");
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const auto *NewExpr2InNewExpr1 =
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Result.Nodes.getNodeAs<CXXNewExpr>("new2_in_new1");
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if (!NewExpr2)
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NewExpr2 = NewExpr2InNewExpr1;
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assert(NewExpr1 && NewExpr2 && "Bound nodes not found.");
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// No warning if both allocations are not stored.
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// The value may be intentionally not stored (no deallocations needed or
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// self-destructing object).
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if (!isExprValueStored(NewExpr1, *Result.Context) &&
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!isExprValueStored(NewExpr2, *Result.Context))
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return;
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// In C++17 sequencing of a 'new' inside constructor arguments of another
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// 'new' is fixed. Still a leak can happen if the returned value from the
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// first 'new' is not saved (yet) and the second fails.
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if (getLangOpts().CPlusPlus17 && NewExpr2InNewExpr1)
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diag(NewExpr1->getBeginLoc(),
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"memory allocation may leak if an other allocation is sequenced after "
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"it and throws an exception")
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<< NewExpr1->getSourceRange() << NewExpr2->getSourceRange();
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else
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diag(NewExpr1->getBeginLoc(),
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"memory allocation may leak if an other allocation is sequenced after "
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"it and throws an exception; order of these allocations is undefined")
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<< NewExpr1->getSourceRange() << NewExpr2->getSourceRange();
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}
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} // namespace clang::tidy::bugprone
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