BoolPointerImplicitConversionCheck.cpp
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//===--- BoolPointerImplicitConversionCheck.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 "BoolPointerImplicitConversionCheck.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace bugprone {
void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
// Look for ifs that have an implicit bool* to bool conversion in the
// condition. Filter negations.
Finder->addMatcher(
traverse(
ast_type_traits::TK_AsIs,
ifStmt(
hasCondition(findAll(implicitCastExpr(
unless(hasParent(unaryOperator(hasOperatorName("!")))),
hasSourceExpression(expr(
hasType(pointerType(pointee(booleanType()))),
ignoringParenImpCasts(anyOf(declRefExpr().bind("expr"),
memberExpr().bind("expr"))))),
hasCastKind(CK_PointerToBoolean)))),
unless(isInTemplateInstantiation()))
.bind("if")),
this);
}
static void checkImpl(const MatchFinder::MatchResult &Result, const Expr *Ref,
const IfStmt *If,
const ast_matchers::internal::Matcher<Expr> &RefMatcher,
ClangTidyCheck &Check) {
// Ignore macros.
if (Ref->getBeginLoc().isMacroID())
return;
// Only allow variable accesses and member exprs for now, no function calls.
// Check that we don't dereference the variable anywhere within the if. This
// avoids false positives for checks of the pointer for nullptr before it is
// dereferenced. If there is a dereferencing operator on this variable don't
// emit a diagnostic. Also ignore array subscripts.
if (!match(findAll(unaryOperator(hasOperatorName("*"),
hasUnaryOperand(RefMatcher))),
*If, *Result.Context)
.empty() ||
!match(findAll(arraySubscriptExpr(hasBase(RefMatcher))), *If,
*Result.Context)
.empty() ||
// FIXME: We should still warn if the paremater is implicitly converted to
// bool.
!match(
findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(RefMatcher)))),
*If, *Result.Context)
.empty() ||
!match(
findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(RefMatcher))))),
*If, *Result.Context)
.empty())
return;
Check.diag(Ref->getBeginLoc(),
"dubious check of 'bool *' against 'nullptr', did "
"you mean to dereference it?")
<< FixItHint::CreateInsertion(Ref->getBeginLoc(), "*");
}
void BoolPointerImplicitConversionCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
if (const auto *E = Result.Nodes.getNodeAs<Expr>("expr")) {
const Decl *D = isa<DeclRefExpr>(E) ? cast<DeclRefExpr>(E)->getDecl()
: cast<MemberExpr>(E)->getMemberDecl();
const auto M =
ignoringParenImpCasts(anyOf(declRefExpr(to(equalsNode(D))),
memberExpr(hasDeclaration(equalsNode(D)))));
checkImpl(Result, E, If, M, *this);
}
}
} // namespace bugprone
} // namespace tidy
} // namespace clang