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 traverse(
22 ast_type_traits::TK_AsIs,
23 ifStmt(hasCondition(findAll(implicitCastExpr(
24 unless(hasParent(unaryOperator(hasOperatorName("!")))),
25 hasSourceExpression(expr(
26 hasType(pointerType(pointee(booleanType()))),
27 ignoringParenImpCasts(declRefExpr().bind("expr")))),
28 hasCastKind(CK_PointerToBoolean)))),
29 unless(isInTemplateInstantiation()))
30 .bind("if")),
31 this);
32 }
33
check(const MatchFinder::MatchResult & Result)34 void BoolPointerImplicitConversionCheck::check(
35 const MatchFinder::MatchResult &Result) {
36 auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
37 auto *Var = Result.Nodes.getNodeAs<DeclRefExpr>("expr");
38
39 // Ignore macros.
40 if (Var->getBeginLoc().isMacroID())
41 return;
42
43 // Only allow variable accesses for now, no function calls or member exprs.
44 // Check that we don't dereference the variable anywhere within the if. This
45 // avoids false positives for checks of the pointer for nullptr before it is
46 // dereferenced. If there is a dereferencing operator on this variable don't
47 // emit a diagnostic. Also ignore array subscripts.
48 const Decl *D = Var->getDecl();
49 auto DeclRef = ignoringParenImpCasts(declRefExpr(to(equalsNode(D))));
50 if (!match(findAll(
51 unaryOperator(hasOperatorName("*"), hasUnaryOperand(DeclRef))),
52 *If, *Result.Context)
53 .empty() ||
54 !match(findAll(arraySubscriptExpr(hasBase(DeclRef))), *If,
55 *Result.Context)
56 .empty() ||
57 // FIXME: We should still warn if the paremater is implicitly converted to
58 // bool.
59 !match(findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(DeclRef)))),
60 *If, *Result.Context)
61 .empty() ||
62 !match(findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(DeclRef))))),
63 *If, *Result.Context)
64 .empty())
65 return;
66
67 diag(Var->getBeginLoc(), "dubious check of 'bool *' against 'nullptr', did "
68 "you mean to dereference it?")
69 << FixItHint::CreateInsertion(Var->getBeginLoc(), "*");
70 }
71
72 } // namespace bugprone
73 } // namespace tidy
74 } // namespace clang
75