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::tidy::bugprone {
14
registerMatchers(MatchFinder * Finder)15 void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
16 // Look for ifs that have an implicit bool* to bool conversion in the
17 // condition. Filter negations.
18 Finder->addMatcher(
19 traverse(
20 TK_AsIs,
21 ifStmt(
22 hasCondition(findAll(implicitCastExpr(
23 unless(hasParent(unaryOperator(hasOperatorName("!")))),
24 hasSourceExpression(expr(
25 hasType(pointerType(pointee(booleanType()))),
26 ignoringParenImpCasts(anyOf(declRefExpr().bind("expr"),
27 memberExpr().bind("expr"))))),
28 hasCastKind(CK_PointerToBoolean)))),
29 unless(isInTemplateInstantiation()))
30 .bind("if")),
31 this);
32 }
33
checkImpl(const MatchFinder::MatchResult & Result,const Expr * Ref,const IfStmt * If,const ast_matchers::internal::Matcher<Expr> & RefMatcher,ClangTidyCheck & Check)34 static void checkImpl(const MatchFinder::MatchResult &Result, const Expr *Ref,
35 const IfStmt *If,
36 const ast_matchers::internal::Matcher<Expr> &RefMatcher,
37 ClangTidyCheck &Check) {
38 // Ignore macros.
39 if (Ref->getBeginLoc().isMacroID())
40 return;
41
42 // Only allow variable accesses and member exprs for now, no function calls.
43 // Check that we don't dereference the variable anywhere within the if. This
44 // avoids false positives for checks of the pointer for nullptr before it is
45 // dereferenced. If there is a dereferencing operator on this variable don't
46 // emit a diagnostic. Also ignore array subscripts.
47 if (!match(findAll(unaryOperator(hasOperatorName("*"),
48 hasUnaryOperand(RefMatcher))),
49 *If, *Result.Context)
50 .empty() ||
51 !match(findAll(arraySubscriptExpr(hasBase(RefMatcher))), *If,
52 *Result.Context)
53 .empty() ||
54 // FIXME: We should still warn if the paremater is implicitly converted to
55 // bool.
56 !match(
57 findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(RefMatcher)))),
58 *If, *Result.Context)
59 .empty() ||
60 !match(
61 findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(RefMatcher))))),
62 *If, *Result.Context)
63 .empty())
64 return;
65
66 Check.diag(Ref->getBeginLoc(),
67 "dubious check of 'bool *' against 'nullptr', did "
68 "you mean to dereference it?")
69 << FixItHint::CreateInsertion(Ref->getBeginLoc(), "*");
70 }
71
check(const MatchFinder::MatchResult & Result)72 void BoolPointerImplicitConversionCheck::check(
73 const MatchFinder::MatchResult &Result) {
74 const auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
75 if (const auto *E = Result.Nodes.getNodeAs<Expr>("expr")) {
76 const Decl *D = isa<DeclRefExpr>(E) ? cast<DeclRefExpr>(E)->getDecl()
77 : cast<MemberExpr>(E)->getMemberDecl();
78 const auto M =
79 ignoringParenImpCasts(anyOf(declRefExpr(to(equalsNode(D))),
80 memberExpr(hasDeclaration(equalsNode(D)))));
81 checkImpl(Result, E, If, M, *this);
82 }
83 }
84
85 } // namespace clang::tidy::bugprone
86