1 //===--- BoolPointerImplicitConversionCheck.cpp - clang-tidy --------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "BoolPointerImplicitConversionCheck.h"
10
11 using namespace clang::ast_matchers;
12
13 namespace clang {
14 namespace tidy {
15 namespace bugprone {
16
registerMatchers(MatchFinder * Finder)17 void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
18 // Look for ifs that have an implicit bool* to bool conversion in the
19 // condition. Filter negations.
20 Finder->addMatcher(
21 ifStmt(hasCondition(findAll(implicitCastExpr(
22 unless(hasParent(unaryOperator(hasOperatorName("!")))),
23 hasSourceExpression(
24 expr(hasType(pointerType(pointee(booleanType()))),
25 ignoringParenImpCasts(declRefExpr().bind("expr")))),
26 hasCastKind(CK_PointerToBoolean)))),
27 unless(isInTemplateInstantiation()))
28 .bind("if"),
29 this);
30 }
31
check(const MatchFinder::MatchResult & Result)32 void BoolPointerImplicitConversionCheck::check(
33 const MatchFinder::MatchResult &Result) {
34 auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
35 auto *Var = Result.Nodes.getNodeAs<DeclRefExpr>("expr");
36
37 // Ignore macros.
38 if (Var->getBeginLoc().isMacroID())
39 return;
40
41 // Only allow variable accesses for now, no function calls or member exprs.
42 // Check that we don't dereference the variable anywhere within the if. This
43 // avoids false positives for checks of the pointer for nullptr before it is
44 // dereferenced. If there is a dereferencing operator on this variable don't
45 // emit a diagnostic. Also ignore array subscripts.
46 const Decl *D = Var->getDecl();
47 auto DeclRef = ignoringParenImpCasts(declRefExpr(to(equalsNode(D))));
48 if (!match(findAll(
49 unaryOperator(hasOperatorName("*"), hasUnaryOperand(DeclRef))),
50 *If, *Result.Context)
51 .empty() ||
52 !match(findAll(arraySubscriptExpr(hasBase(DeclRef))), *If,
53 *Result.Context)
54 .empty() ||
55 // FIXME: We should still warn if the paremater is implicitly converted to
56 // bool.
57 !match(findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(DeclRef)))),
58 *If, *Result.Context)
59 .empty() ||
60 !match(findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(DeclRef))))),
61 *If, *Result.Context)
62 .empty())
63 return;
64
65 diag(Var->getBeginLoc(), "dubious check of 'bool *' against 'nullptr', did "
66 "you mean to dereference it?")
67 << FixItHint::CreateInsertion(Var->getBeginLoc(), "*");
68 }
69
70 } // namespace bugprone
71 } // namespace tidy
72 } // namespace clang
73