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 TK_AsIs,
23 ifStmt(
24 hasCondition(findAll(implicitCastExpr(
25 unless(hasParent(unaryOperator(hasOperatorName("!")))),
26 hasSourceExpression(expr(
27 hasType(pointerType(pointee(booleanType()))),
28 ignoringParenImpCasts(anyOf(declRefExpr().bind("expr"),
29 memberExpr().bind("expr"))))),
30 hasCastKind(CK_PointerToBoolean)))),
31 unless(isInTemplateInstantiation()))
32 .bind("if")),
33 this);
34 }
35
checkImpl(const MatchFinder::MatchResult & Result,const Expr * Ref,const IfStmt * If,const ast_matchers::internal::Matcher<Expr> & RefMatcher,ClangTidyCheck & Check)36 static void checkImpl(const MatchFinder::MatchResult &Result, const Expr *Ref,
37 const IfStmt *If,
38 const ast_matchers::internal::Matcher<Expr> &RefMatcher,
39 ClangTidyCheck &Check) {
40 // Ignore macros.
41 if (Ref->getBeginLoc().isMacroID())
42 return;
43
44 // Only allow variable accesses and member exprs for now, no function calls.
45 // Check that we don't dereference the variable anywhere within the if. This
46 // avoids false positives for checks of the pointer for nullptr before it is
47 // dereferenced. If there is a dereferencing operator on this variable don't
48 // emit a diagnostic. Also ignore array subscripts.
49 if (!match(findAll(unaryOperator(hasOperatorName("*"),
50 hasUnaryOperand(RefMatcher))),
51 *If, *Result.Context)
52 .empty() ||
53 !match(findAll(arraySubscriptExpr(hasBase(RefMatcher))), *If,
54 *Result.Context)
55 .empty() ||
56 // FIXME: We should still warn if the paremater is implicitly converted to
57 // bool.
58 !match(
59 findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(RefMatcher)))),
60 *If, *Result.Context)
61 .empty() ||
62 !match(
63 findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(RefMatcher))))),
64 *If, *Result.Context)
65 .empty())
66 return;
67
68 Check.diag(Ref->getBeginLoc(),
69 "dubious check of 'bool *' against 'nullptr', did "
70 "you mean to dereference it?")
71 << FixItHint::CreateInsertion(Ref->getBeginLoc(), "*");
72 }
73
check(const MatchFinder::MatchResult & Result)74 void BoolPointerImplicitConversionCheck::check(
75 const MatchFinder::MatchResult &Result) {
76 const auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
77 if (const auto *E = Result.Nodes.getNodeAs<Expr>("expr")) {
78 const Decl *D = isa<DeclRefExpr>(E) ? cast<DeclRefExpr>(E)->getDecl()
79 : cast<MemberExpr>(E)->getMemberDecl();
80 const auto M =
81 ignoringParenImpCasts(anyOf(declRefExpr(to(equalsNode(D))),
82 memberExpr(hasDeclaration(equalsNode(D)))));
83 checkImpl(Result, E, If, M, *this);
84 }
85 }
86
87 } // namespace bugprone
88 } // namespace tidy
89 } // namespace clang
90