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//===--- ImplicitBoolConversionCheck.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 "ImplicitBoolConversionCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Lex/Lexer.h"
#include "clang/Tooling/FixIt.h"
#include <queue>
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace readability {
namespace {
AST_MATCHER(Stmt, isMacroExpansion) {
SourceManager &SM = Finder->getASTContext().getSourceManager();
SourceLocation Loc = Node.getBeginLoc();
return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
}
bool isNULLMacroExpansion(const Stmt *Statement, ASTContext &Context) {
SourceManager &SM = Context.getSourceManager();
const LangOptions &LO = Context.getLangOpts();
SourceLocation Loc = Statement->getBeginLoc();
return SM.isMacroBodyExpansion(Loc) &&
Lexer::getImmediateMacroName(Loc, SM, LO) == "NULL";
}
AST_MATCHER(Stmt, isNULLMacroExpansion) {
return isNULLMacroExpansion(&Node, Finder->getASTContext());
}
StringRef getZeroLiteralToCompareWithForType(CastKind CastExprKind,
QualType Type,
ASTContext &Context) {
switch (CastExprKind) {
case CK_IntegralToBoolean:
return Type->isUnsignedIntegerType() ? "0u" : "0";
case CK_FloatingToBoolean:
return Context.hasSameType(Type, Context.FloatTy) ? "0.0f" : "0.0";
case CK_PointerToBoolean:
case CK_MemberPointerToBoolean: // Fall-through on purpose.
return Context.getLangOpts().CPlusPlus11 ? "nullptr" : "0";
default:
llvm_unreachable("Unexpected cast kind");
}
}
bool isUnaryLogicalNotOperator(const Stmt *Statement) {
const auto *UnaryOperatorExpr = dyn_cast<UnaryOperator>(Statement);
return UnaryOperatorExpr && UnaryOperatorExpr->getOpcode() == UO_LNot;
}
bool areParensNeededForOverloadedOperator(OverloadedOperatorKind OperatorKind) {
switch (OperatorKind) {
case OO_New:
case OO_Delete: // Fall-through on purpose.
case OO_Array_New:
case OO_Array_Delete:
case OO_ArrowStar:
case OO_Arrow:
case OO_Call:
case OO_Subscript:
return false;
default:
return true;
}
}
bool areParensNeededForStatement(const Stmt *Statement) {
if (const auto *OperatorCall = dyn_cast<CXXOperatorCallExpr>(Statement)) {
return areParensNeededForOverloadedOperator(OperatorCall->getOperator());
}
return isa<BinaryOperator>(Statement) || isa<UnaryOperator>(Statement);
}
void fixGenericExprCastToBool(DiagnosticBuilder &Diag,
const ImplicitCastExpr *Cast, const Stmt *Parent,
ASTContext &Context) {
// In case of expressions like (! integer), we should remove the redundant not
// operator and use inverted comparison (integer == 0).
bool InvertComparison =
Parent != nullptr && isUnaryLogicalNotOperator(Parent);
if (InvertComparison) {
SourceLocation ParentStartLoc = Parent->getBeginLoc();
SourceLocation ParentEndLoc =
cast<UnaryOperator>(Parent)->getSubExpr()->getBeginLoc();
Diag << FixItHint::CreateRemoval(
CharSourceRange::getCharRange(ParentStartLoc, ParentEndLoc));
Parent = Context.getParents(*Parent)[0].get<Stmt>();
}
const Expr *SubExpr = Cast->getSubExpr();
bool NeedInnerParens = areParensNeededForStatement(SubExpr);
bool NeedOuterParens =
Parent != nullptr && areParensNeededForStatement(Parent);
std::string StartLocInsertion;
if (NeedOuterParens) {
StartLocInsertion += "(";
}
if (NeedInnerParens) {
StartLocInsertion += "(";
}
if (!StartLocInsertion.empty()) {
Diag << FixItHint::CreateInsertion(Cast->getBeginLoc(), StartLocInsertion);
}
std::string EndLocInsertion;
if (NeedInnerParens) {
EndLocInsertion += ")";
}
if (InvertComparison) {
EndLocInsertion += " == ";
} else {
EndLocInsertion += " != ";
}
EndLocInsertion += getZeroLiteralToCompareWithForType(
Cast->getCastKind(), SubExpr->getType(), Context);
if (NeedOuterParens) {
EndLocInsertion += ")";
}
SourceLocation EndLoc = Lexer::getLocForEndOfToken(
Cast->getEndLoc(), 0, Context.getSourceManager(), Context.getLangOpts());
Diag << FixItHint::CreateInsertion(EndLoc, EndLocInsertion);
}
StringRef getEquivalentBoolLiteralForExpr(const Expr *Expression,
ASTContext &Context) {
if (isNULLMacroExpansion(Expression, Context)) {
return "false";
}
if (const auto *IntLit = dyn_cast<IntegerLiteral>(Expression)) {
return (IntLit->getValue() == 0) ? "false" : "true";
}
if (const auto *FloatLit = dyn_cast<FloatingLiteral>(Expression)) {
llvm::APFloat FloatLitAbsValue = FloatLit->getValue();
FloatLitAbsValue.clearSign();
return (FloatLitAbsValue.bitcastToAPInt() == 0) ? "false" : "true";
}
if (const auto *CharLit = dyn_cast<CharacterLiteral>(Expression)) {
return (CharLit->getValue() == 0) ? "false" : "true";
}
if (isa<StringLiteral>(Expression->IgnoreCasts())) {
return "true";
}
return StringRef();
}
void fixGenericExprCastFromBool(DiagnosticBuilder &Diag,
const ImplicitCastExpr *Cast,
ASTContext &Context, StringRef OtherType) {
const Expr *SubExpr = Cast->getSubExpr();
bool NeedParens = !isa<ParenExpr>(SubExpr);
Diag << FixItHint::CreateInsertion(
Cast->getBeginLoc(),
(Twine("static_cast<") + OtherType + ">" + (NeedParens ? "(" : ""))
.str());
if (NeedParens) {
SourceLocation EndLoc = Lexer::getLocForEndOfToken(
Cast->getEndLoc(), 0, Context.getSourceManager(),
Context.getLangOpts());
Diag << FixItHint::CreateInsertion(EndLoc, ")");
}
}
StringRef getEquivalentForBoolLiteral(const CXXBoolLiteralExpr *BoolLiteral,
QualType DestType, ASTContext &Context) {
// Prior to C++11, false literal could be implicitly converted to pointer.
if (!Context.getLangOpts().CPlusPlus11 &&
(DestType->isPointerType() || DestType->isMemberPointerType()) &&
BoolLiteral->getValue() == false) {
return "0";
}
if (DestType->isFloatingType()) {
if (Context.hasSameType(DestType, Context.FloatTy)) {
return BoolLiteral->getValue() ? "1.0f" : "0.0f";
}
return BoolLiteral->getValue() ? "1.0" : "0.0";
}
if (DestType->isUnsignedIntegerType()) {
return BoolLiteral->getValue() ? "1u" : "0u";
}
return BoolLiteral->getValue() ? "1" : "0";
}
bool isCastAllowedInCondition(const ImplicitCastExpr *Cast,
ASTContext &Context) {
std::queue<const Stmt *> Q;
Q.push(Cast);
TraversalKindScope RAII(Context, TK_AsIs);
while (!Q.empty()) {
for (const auto &N : Context.getParents(*Q.front())) {
const Stmt *S = N.get<Stmt>();
if (!S)
return false;
if (isa<IfStmt>(S) || isa<ConditionalOperator>(S) || isa<ForStmt>(S) ||
isa<WhileStmt>(S) || isa<BinaryConditionalOperator>(S))
return true;
if (isa<ParenExpr>(S) || isa<ImplicitCastExpr>(S) ||
isUnaryLogicalNotOperator(S) ||
(isa<BinaryOperator>(S) && cast<BinaryOperator>(S)->isLogicalOp())) {
Q.push(S);
} else {
return false;
}
}
Q.pop();
}
return false;
}
} // anonymous namespace
ImplicitBoolConversionCheck::ImplicitBoolConversionCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
AllowIntegerConditions(Options.get("AllowIntegerConditions", false)),
AllowPointerConditions(Options.get("AllowPointerConditions", false)) {}
void ImplicitBoolConversionCheck::storeOptions(
ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AllowIntegerConditions", AllowIntegerConditions);
Options.store(Opts, "AllowPointerConditions", AllowPointerConditions);
}
void ImplicitBoolConversionCheck::registerMatchers(MatchFinder *Finder) {
auto ExceptionCases =
expr(anyOf(allOf(isMacroExpansion(), unless(isNULLMacroExpansion())),
has(ignoringImplicit(
memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1)))))),
hasParent(explicitCastExpr())));
auto ImplicitCastFromBool = implicitCastExpr(
anyOf(hasCastKind(CK_IntegralCast), hasCastKind(CK_IntegralToFloating),
// Prior to C++11 cast from bool literal to pointer was allowed.
allOf(anyOf(hasCastKind(CK_NullToPointer),
hasCastKind(CK_NullToMemberPointer)),
hasSourceExpression(cxxBoolLiteral()))),
hasSourceExpression(expr(hasType(booleanType()))),
unless(ExceptionCases));
auto BoolXor =
binaryOperator(hasOperatorName("^"), hasLHS(ImplicitCastFromBool),
hasRHS(ImplicitCastFromBool));
Finder->addMatcher(
traverse(TK_AsIs,
implicitCastExpr(
anyOf(hasCastKind(CK_IntegralToBoolean),
hasCastKind(CK_FloatingToBoolean),
hasCastKind(CK_PointerToBoolean),
hasCastKind(CK_MemberPointerToBoolean)),
// Exclude case of using if or while statements with variable
// declaration, e.g.:
// if (int var = functionCall()) {}
unless(hasParent(
stmt(anyOf(ifStmt(), whileStmt()), has(declStmt())))),
// Exclude cases common to implicit cast to and from bool.
unless(ExceptionCases), unless(has(BoolXor)),
// Retrieve also parent statement, to check if we need
// additional parens in replacement.
anyOf(hasParent(stmt().bind("parentStmt")), anything()),
unless(isInTemplateInstantiation()),
unless(hasAncestor(functionTemplateDecl())))
.bind("implicitCastToBool")),
this);
auto BoolComparison = binaryOperator(hasAnyOperatorName("==", "!="),
hasLHS(ImplicitCastFromBool),
hasRHS(ImplicitCastFromBool));
auto BoolOpAssignment = binaryOperator(hasAnyOperatorName("|=", "&="),
hasLHS(expr(hasType(booleanType()))));
auto BitfieldAssignment = binaryOperator(
hasLHS(memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1))))));
auto BitfieldConstruct = cxxConstructorDecl(hasDescendant(cxxCtorInitializer(
withInitializer(equalsBoundNode("implicitCastFromBool")),
forField(hasBitWidth(1)))));
Finder->addMatcher(
traverse(
TK_AsIs,
implicitCastExpr(
ImplicitCastFromBool,
// Exclude comparisons of bools, as they are always cast to
// integers in such context:
// bool_expr_a == bool_expr_b
// bool_expr_a != bool_expr_b
unless(hasParent(
binaryOperator(anyOf(BoolComparison, BoolXor,
BoolOpAssignment, BitfieldAssignment)))),
implicitCastExpr().bind("implicitCastFromBool"),
unless(hasParent(BitfieldConstruct)),
// Check also for nested casts, for example: bool -> int -> float.
anyOf(hasParent(implicitCastExpr().bind("furtherImplicitCast")),
anything()),
unless(isInTemplateInstantiation()),
unless(hasAncestor(functionTemplateDecl())))),
this);
}
void ImplicitBoolConversionCheck::check(
const MatchFinder::MatchResult &Result) {
if (const auto *CastToBool =
Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastToBool")) {
const auto *Parent = Result.Nodes.getNodeAs<Stmt>("parentStmt");
return handleCastToBool(CastToBool, Parent, *Result.Context);
}
if (const auto *CastFromBool =
Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastFromBool")) {
const auto *NextImplicitCast =
Result.Nodes.getNodeAs<ImplicitCastExpr>("furtherImplicitCast");
return handleCastFromBool(CastFromBool, NextImplicitCast, *Result.Context);
}
}
void ImplicitBoolConversionCheck::handleCastToBool(const ImplicitCastExpr *Cast,
const Stmt *Parent,
ASTContext &Context) {
if (AllowPointerConditions &&
(Cast->getCastKind() == CK_PointerToBoolean ||
Cast->getCastKind() == CK_MemberPointerToBoolean) &&
isCastAllowedInCondition(Cast, Context)) {
return;
}
if (AllowIntegerConditions && Cast->getCastKind() == CK_IntegralToBoolean &&
isCastAllowedInCondition(Cast, Context)) {
return;
}
auto Diag = diag(Cast->getBeginLoc(), "implicit conversion %0 -> bool")
<< Cast->getSubExpr()->getType();
StringRef EquivalentLiteral =
getEquivalentBoolLiteralForExpr(Cast->getSubExpr(), Context);
if (!EquivalentLiteral.empty()) {
Diag << tooling::fixit::createReplacement(*Cast, EquivalentLiteral);
} else {
fixGenericExprCastToBool(Diag, Cast, Parent, Context);
}
}
void ImplicitBoolConversionCheck::handleCastFromBool(
const ImplicitCastExpr *Cast, const ImplicitCastExpr *NextImplicitCast,
ASTContext &Context) {
QualType DestType =
NextImplicitCast ? NextImplicitCast->getType() : Cast->getType();
auto Diag = diag(Cast->getBeginLoc(), "implicit conversion bool -> %0")
<< DestType;
if (const auto *BoolLiteral =
dyn_cast<CXXBoolLiteralExpr>(Cast->getSubExpr())) {
Diag << tooling::fixit::createReplacement(
*Cast, getEquivalentForBoolLiteral(BoolLiteral, DestType, Context));
} else {
fixGenericExprCastFromBool(Diag, Cast, Context, DestType.getAsString());
}
}
} // namespace readability
} // namespace tidy
} // namespace clang