2946cd7010
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
351 lines
14 KiB
C++
351 lines
14 KiB
C++
//===- NumberObjectConversionChecker.cpp -------------------------*- C++ -*-==//
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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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//
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// This file defines NumberObjectConversionChecker, which checks for a
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// particular common mistake when dealing with numbers represented as objects
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// passed around by pointers. Namely, the language allows to reinterpret the
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// pointer as a number directly, often without throwing any warnings,
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// but in most cases the result of such conversion is clearly unexpected,
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// as pointer value, rather than number value represented by the pointee object,
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// becomes the result of such operation.
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//
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// Currently the checker supports the Objective-C NSNumber class,
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// and the OSBoolean class found in macOS low-level code; the latter
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// can only hold boolean values.
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//
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// This checker has an option "Pedantic" (boolean), which enables detection of
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// more conversion patterns (which are most likely more harmless, and therefore
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// are more likely to produce false positives) - disabled by default,
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// enabled with `-analyzer-config osx.NumberObjectConversion:Pedantic=true'.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
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#include "clang/Lex/Lexer.h"
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#include "llvm/ADT/APSInt.h"
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using namespace clang;
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using namespace ento;
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using namespace ast_matchers;
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namespace {
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class NumberObjectConversionChecker : public Checker<check::ASTCodeBody> {
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public:
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bool Pedantic;
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void checkASTCodeBody(const Decl *D, AnalysisManager &AM,
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BugReporter &BR) const;
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};
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class Callback : public MatchFinder::MatchCallback {
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const NumberObjectConversionChecker *C;
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BugReporter &BR;
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AnalysisDeclContext *ADC;
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public:
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Callback(const NumberObjectConversionChecker *C,
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BugReporter &BR, AnalysisDeclContext *ADC)
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: C(C), BR(BR), ADC(ADC) {}
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virtual void run(const MatchFinder::MatchResult &Result);
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};
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} // end of anonymous namespace
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void Callback::run(const MatchFinder::MatchResult &Result) {
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bool IsPedanticMatch =
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(Result.Nodes.getNodeAs<Stmt>("pedantic") != nullptr);
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if (IsPedanticMatch && !C->Pedantic)
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return;
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ASTContext &ACtx = ADC->getASTContext();
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if (const Expr *CheckIfNull =
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Result.Nodes.getNodeAs<Expr>("check_if_null")) {
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// Unless the macro indicates that the intended type is clearly not
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// a pointer type, we should avoid warning on comparing pointers
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// to zero literals in non-pedantic mode.
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// FIXME: Introduce an AST matcher to implement the macro-related logic?
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bool MacroIndicatesWeShouldSkipTheCheck = false;
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SourceLocation Loc = CheckIfNull->getBeginLoc();
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if (Loc.isMacroID()) {
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StringRef MacroName = Lexer::getImmediateMacroName(
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Loc, ACtx.getSourceManager(), ACtx.getLangOpts());
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if (MacroName == "NULL" || MacroName == "nil")
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return;
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if (MacroName == "YES" || MacroName == "NO")
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MacroIndicatesWeShouldSkipTheCheck = true;
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}
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if (!MacroIndicatesWeShouldSkipTheCheck) {
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Expr::EvalResult EVResult;
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if (CheckIfNull->IgnoreParenCasts()->EvaluateAsInt(
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EVResult, ACtx, Expr::SE_AllowSideEffects)) {
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llvm::APSInt Result = EVResult.Val.getInt();
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if (Result == 0) {
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if (!C->Pedantic)
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return;
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IsPedanticMatch = true;
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}
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}
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}
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}
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const Stmt *Conv = Result.Nodes.getNodeAs<Stmt>("conv");
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assert(Conv);
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const Expr *ConvertedCObject = Result.Nodes.getNodeAs<Expr>("c_object");
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const Expr *ConvertedCppObject = Result.Nodes.getNodeAs<Expr>("cpp_object");
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const Expr *ConvertedObjCObject = Result.Nodes.getNodeAs<Expr>("objc_object");
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bool IsCpp = (ConvertedCppObject != nullptr);
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bool IsObjC = (ConvertedObjCObject != nullptr);
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const Expr *Obj = IsObjC ? ConvertedObjCObject
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: IsCpp ? ConvertedCppObject
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: ConvertedCObject;
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assert(Obj);
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bool IsComparison =
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(Result.Nodes.getNodeAs<Stmt>("comparison") != nullptr);
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bool IsOSNumber =
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(Result.Nodes.getNodeAs<Decl>("osnumber") != nullptr);
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bool IsInteger =
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(Result.Nodes.getNodeAs<QualType>("int_type") != nullptr);
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bool IsObjCBool =
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(Result.Nodes.getNodeAs<QualType>("objc_bool_type") != nullptr);
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bool IsCppBool =
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(Result.Nodes.getNodeAs<QualType>("cpp_bool_type") != nullptr);
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llvm::SmallString<64> Msg;
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llvm::raw_svector_ostream OS(Msg);
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// Remove ObjC ARC qualifiers.
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QualType ObjT = Obj->getType().getUnqualifiedType();
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// Remove consts from pointers.
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if (IsCpp) {
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assert(ObjT.getCanonicalType()->isPointerType());
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ObjT = ACtx.getPointerType(
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ObjT->getPointeeType().getCanonicalType().getUnqualifiedType());
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}
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if (IsComparison)
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OS << "Comparing ";
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else
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OS << "Converting ";
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OS << "a pointer value of type '" << ObjT.getAsString() << "' to a ";
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std::string EuphemismForPlain = "primitive";
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std::string SuggestedApi = IsObjC ? (IsInteger ? "" : "-boolValue")
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: IsCpp ? (IsOSNumber ? "" : "getValue()")
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: "CFNumberGetValue()";
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if (SuggestedApi.empty()) {
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// A generic message if we're not sure what API should be called.
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// FIXME: Pattern-match the integer type to make a better guess?
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SuggestedApi =
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"a method on '" + ObjT.getAsString() + "' to get the scalar value";
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// "scalar" is not quite correct or common, but some documentation uses it
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// when describing object methods we suggest. For consistency, we use
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// "scalar" in the whole sentence when we need to use this word in at least
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// one place, otherwise we use "primitive".
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EuphemismForPlain = "scalar";
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}
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if (IsInteger)
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OS << EuphemismForPlain << " integer value";
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else if (IsObjCBool)
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OS << EuphemismForPlain << " BOOL value";
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else if (IsCppBool)
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OS << EuphemismForPlain << " bool value";
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else // Branch condition?
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OS << EuphemismForPlain << " boolean value";
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if (IsPedanticMatch)
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OS << "; instead, either compare the pointer to "
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<< (IsObjC ? "nil" : IsCpp ? "nullptr" : "NULL") << " or ";
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else
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OS << "; did you mean to ";
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if (IsComparison)
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OS << "compare the result of calling " << SuggestedApi;
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else
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OS << "call " << SuggestedApi;
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if (!IsPedanticMatch)
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OS << "?";
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BR.EmitBasicReport(
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ADC->getDecl(), C, "Suspicious number object conversion", "Logic error",
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OS.str(),
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PathDiagnosticLocation::createBegin(Obj, BR.getSourceManager(), ADC),
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Conv->getSourceRange());
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}
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void NumberObjectConversionChecker::checkASTCodeBody(const Decl *D,
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AnalysisManager &AM,
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BugReporter &BR) const {
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// Currently this matches CoreFoundation opaque pointer typedefs.
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auto CSuspiciousNumberObjectExprM =
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expr(ignoringParenImpCasts(
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expr(hasType(
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typedefType(hasDeclaration(anyOf(
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typedefDecl(hasName("CFNumberRef")),
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typedefDecl(hasName("CFBooleanRef")))))))
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.bind("c_object")));
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// Currently this matches XNU kernel number-object pointers.
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auto CppSuspiciousNumberObjectExprM =
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expr(ignoringParenImpCasts(
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expr(hasType(hasCanonicalType(
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pointerType(pointee(hasCanonicalType(
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recordType(hasDeclaration(
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anyOf(
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cxxRecordDecl(hasName("OSBoolean")),
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cxxRecordDecl(hasName("OSNumber"))
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.bind("osnumber"))))))))))
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.bind("cpp_object")));
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// Currently this matches NeXTSTEP number objects.
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auto ObjCSuspiciousNumberObjectExprM =
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expr(ignoringParenImpCasts(
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expr(hasType(hasCanonicalType(
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objcObjectPointerType(pointee(
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qualType(hasCanonicalType(
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qualType(hasDeclaration(
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objcInterfaceDecl(hasName("NSNumber")))))))))))
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.bind("objc_object")));
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auto SuspiciousNumberObjectExprM = anyOf(
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CSuspiciousNumberObjectExprM,
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CppSuspiciousNumberObjectExprM,
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ObjCSuspiciousNumberObjectExprM);
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// Useful for predicates like "Unless we've seen the same object elsewhere".
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auto AnotherSuspiciousNumberObjectExprM =
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expr(anyOf(
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equalsBoundNode("c_object"),
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equalsBoundNode("objc_object"),
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equalsBoundNode("cpp_object")));
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// The .bind here is in order to compose the error message more accurately.
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auto ObjCSuspiciousScalarBooleanTypeM =
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qualType(typedefType(hasDeclaration(
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typedefDecl(hasName("BOOL"))))).bind("objc_bool_type");
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// The .bind here is in order to compose the error message more accurately.
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auto SuspiciousScalarBooleanTypeM =
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qualType(anyOf(qualType(booleanType()).bind("cpp_bool_type"),
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ObjCSuspiciousScalarBooleanTypeM));
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// The .bind here is in order to compose the error message more accurately.
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// Also avoid intptr_t and uintptr_t because they were specifically created
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// for storing pointers.
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auto SuspiciousScalarNumberTypeM =
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qualType(hasCanonicalType(isInteger()),
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unless(typedefType(hasDeclaration(
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typedefDecl(matchesName("^::u?intptr_t$"))))))
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.bind("int_type");
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auto SuspiciousScalarTypeM =
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qualType(anyOf(SuspiciousScalarBooleanTypeM,
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SuspiciousScalarNumberTypeM));
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auto SuspiciousScalarExprM =
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expr(ignoringParenImpCasts(expr(hasType(SuspiciousScalarTypeM))));
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auto ConversionThroughAssignmentM =
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binaryOperator(allOf(hasOperatorName("="),
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hasLHS(SuspiciousScalarExprM),
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hasRHS(SuspiciousNumberObjectExprM)));
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auto ConversionThroughBranchingM =
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ifStmt(allOf(
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hasCondition(SuspiciousNumberObjectExprM),
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unless(hasConditionVariableStatement(declStmt())
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))).bind("pedantic");
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auto ConversionThroughCallM =
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callExpr(hasAnyArgument(allOf(hasType(SuspiciousScalarTypeM),
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ignoringParenImpCasts(
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SuspiciousNumberObjectExprM))));
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// We bind "check_if_null" to modify the warning message
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// in case it was intended to compare a pointer to 0 with a relatively-ok
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// construct "x == 0" or "x != 0".
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auto ConversionThroughEquivalenceM =
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binaryOperator(allOf(anyOf(hasOperatorName("=="), hasOperatorName("!=")),
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hasEitherOperand(SuspiciousNumberObjectExprM),
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hasEitherOperand(SuspiciousScalarExprM
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.bind("check_if_null"))))
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.bind("comparison");
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auto ConversionThroughComparisonM =
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binaryOperator(allOf(anyOf(hasOperatorName(">="), hasOperatorName(">"),
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hasOperatorName("<="), hasOperatorName("<")),
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hasEitherOperand(SuspiciousNumberObjectExprM),
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hasEitherOperand(SuspiciousScalarExprM)))
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.bind("comparison");
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auto ConversionThroughConditionalOperatorM =
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conditionalOperator(allOf(
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hasCondition(SuspiciousNumberObjectExprM),
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unless(hasTrueExpression(
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hasDescendant(AnotherSuspiciousNumberObjectExprM))),
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unless(hasFalseExpression(
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hasDescendant(AnotherSuspiciousNumberObjectExprM)))))
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.bind("pedantic");
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auto ConversionThroughExclamationMarkM =
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unaryOperator(allOf(hasOperatorName("!"),
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has(expr(SuspiciousNumberObjectExprM))))
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.bind("pedantic");
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auto ConversionThroughExplicitBooleanCastM =
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explicitCastExpr(allOf(hasType(SuspiciousScalarBooleanTypeM),
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has(expr(SuspiciousNumberObjectExprM))));
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auto ConversionThroughExplicitNumberCastM =
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explicitCastExpr(allOf(hasType(SuspiciousScalarNumberTypeM),
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has(expr(SuspiciousNumberObjectExprM))));
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auto ConversionThroughInitializerM =
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declStmt(hasSingleDecl(
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varDecl(hasType(SuspiciousScalarTypeM),
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hasInitializer(SuspiciousNumberObjectExprM))));
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auto FinalM = stmt(anyOf(ConversionThroughAssignmentM,
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ConversionThroughBranchingM,
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ConversionThroughCallM,
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ConversionThroughComparisonM,
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ConversionThroughConditionalOperatorM,
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ConversionThroughEquivalenceM,
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ConversionThroughExclamationMarkM,
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ConversionThroughExplicitBooleanCastM,
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ConversionThroughExplicitNumberCastM,
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ConversionThroughInitializerM)).bind("conv");
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MatchFinder F;
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Callback CB(this, BR, AM.getAnalysisDeclContext(D));
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F.addMatcher(stmt(forEachDescendant(FinalM)), &CB);
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F.match(*D->getBody(), AM.getASTContext());
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}
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void ento::registerNumberObjectConversionChecker(CheckerManager &Mgr) {
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NumberObjectConversionChecker *Chk =
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Mgr.registerChecker<NumberObjectConversionChecker>();
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Chk->Pedantic =
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Mgr.getAnalyzerOptions().getCheckerBooleanOption("Pedantic", false, Chk);
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}
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