NSInvocationArgumentLifetimeCheck.cpp
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//===--- NSInvocationArgumentLifetimeCheck.cpp - clang-tidy ---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "NSInvocationArgumentLifetimeCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ComputeDependence.h"
#include "clang/AST/Decl.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/Type.h"
#include "clang/AST/TypeLoc.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/ASTMatchers/ASTMatchersMacros.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Lex/Lexer.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace objc {
namespace {
static constexpr StringRef WeakText = "__weak";
static constexpr StringRef StrongText = "__strong";
static constexpr StringRef UnsafeUnretainedText = "__unsafe_unretained";
/// Matches ObjCIvarRefExpr, DeclRefExpr, or MemberExpr that reference
/// Objective-C object (or block) variables or fields whose object lifetimes
/// are not __unsafe_unretained.
AST_POLYMORPHIC_MATCHER(isObjCManagedLifetime,
AST_POLYMORPHIC_SUPPORTED_TYPES(ObjCIvarRefExpr,
DeclRefExpr,
MemberExpr)) {
QualType QT = Node.getType();
return QT->isScalarType() &&
(QT->getScalarTypeKind() == Type::STK_ObjCObjectPointer ||
QT->getScalarTypeKind() == Type::STK_BlockPointer) &&
QT.getQualifiers().getObjCLifetime() > Qualifiers::OCL_ExplicitNone;
}
static llvm::Optional<FixItHint>
fixItHintReplacementForOwnershipString(StringRef Text, CharSourceRange Range,
StringRef Ownership) {
size_t Index = Text.find(Ownership);
if (Index == StringRef::npos)
return llvm::None;
SourceLocation Begin = Range.getBegin().getLocWithOffset(Index);
SourceLocation End = Begin.getLocWithOffset(Ownership.size());
return FixItHint::CreateReplacement(SourceRange(Begin, End),
UnsafeUnretainedText);
}
static llvm::Optional<FixItHint>
fixItHintForVarDecl(const VarDecl *VD, const SourceManager &SM,
const LangOptions &LangOpts) {
assert(VD && "VarDecl parameter must not be null");
// Don't provide fix-its for any parameter variables at this time.
if (isa<ParmVarDecl>(VD))
return llvm::None;
// Currently there is no way to directly get the source range for the
// __weak/__strong ObjC lifetime qualifiers, so it's necessary to string
// search in the source code.
CharSourceRange Range = Lexer::makeFileCharRange(
CharSourceRange::getTokenRange(VD->getSourceRange()), SM, LangOpts);
if (Range.isInvalid()) {
// An invalid range likely means inside a macro, in which case don't supply
// a fix-it.
return llvm::None;
}
StringRef VarDeclText = Lexer::getSourceText(Range, SM, LangOpts);
if (llvm::Optional<FixItHint> Hint =
fixItHintReplacementForOwnershipString(VarDeclText, Range, WeakText))
return Hint;
if (llvm::Optional<FixItHint> Hint = fixItHintReplacementForOwnershipString(
VarDeclText, Range, StrongText))
return Hint;
return FixItHint::CreateInsertion(Range.getBegin(), "__unsafe_unretained ");
}
} // namespace
void NSInvocationArgumentLifetimeCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
traverse(
ast_type_traits::TK_AsIs,
objcMessageExpr(
hasReceiverType(asString("NSInvocation *")),
anyOf(hasSelector("getArgument:atIndex:"),
hasSelector("getReturnValue:")),
hasArgument(
0,
anyOf(hasDescendant(memberExpr(isObjCManagedLifetime())),
hasDescendant(objcIvarRefExpr(isObjCManagedLifetime())),
hasDescendant(
// Reference to variables, but when dereferencing
// to ivars/fields a more-descendent variable
// reference (e.g. self) may match with strong
// object lifetime, leading to an incorrect match.
// Exclude these conditions.
declRefExpr(to(varDecl().bind("var")),
unless(hasParent(implicitCastExpr())),
isObjCManagedLifetime())))))
.bind("call")),
this);
}
void NSInvocationArgumentLifetimeCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *MatchedExpr = Result.Nodes.getNodeAs<ObjCMessageExpr>("call");
auto Diag = diag(MatchedExpr->getArg(0)->getBeginLoc(),
"NSInvocation %objcinstance0 should only pass pointers to "
"objects with ownership __unsafe_unretained")
<< MatchedExpr->getSelector();
// Only provide fix-it hints for references to local variables; fixes for
// instance variable references don't have as clear an automated fix.
const auto *VD = Result.Nodes.getNodeAs<VarDecl>("var");
if (!VD)
return;
if (auto Hint = fixItHintForVarDecl(VD, *Result.SourceManager,
Result.Context->getLangOpts()))
Diag << *Hint;
}
} // namespace objc
} // namespace tidy
} // namespace clang