1 //===--- MultiLevelImplicitPointerConversionCheck.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 "MultiLevelImplicitPointerConversionCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang::tidy::bugprone {
16
getPointerLevel(const QualType & PtrType)17 static unsigned getPointerLevel(const QualType &PtrType) {
18 if (!PtrType->isPointerType())
19 return 0U;
20
21 return 1U + getPointerLevel(PtrType->castAs<PointerType>()->getPointeeType());
22 }
23
24 namespace {
25
AST_MATCHER(ImplicitCastExpr,isMultiLevelPointerConversion)26 AST_MATCHER(ImplicitCastExpr, isMultiLevelPointerConversion) {
27 const QualType TargetType = Node.getType()
28 .getCanonicalType()
29 .getNonReferenceType()
30 .getUnqualifiedType();
31 const QualType SourceType = Node.getSubExpr()
32 ->getType()
33 .getCanonicalType()
34 .getNonReferenceType()
35 .getUnqualifiedType();
36
37 if (TargetType == SourceType)
38 return false;
39
40 const unsigned TargetPtrLevel = getPointerLevel(TargetType);
41 if (0U == TargetPtrLevel)
42 return false;
43
44 const unsigned SourcePtrLevel = getPointerLevel(SourceType);
45 if (0U == SourcePtrLevel)
46 return false;
47
48 return SourcePtrLevel != TargetPtrLevel;
49 }
50
AST_MATCHER(QualType,isPointerType)51 AST_MATCHER(QualType, isPointerType) {
52 const QualType Type =
53 Node.getCanonicalType().getNonReferenceType().getUnqualifiedType();
54
55 return !Type.isNull() && Type->isPointerType();
56 }
57
58 } // namespace
59
registerMatchers(MatchFinder * Finder)60 void MultiLevelImplicitPointerConversionCheck::registerMatchers(
61 MatchFinder *Finder) {
62 Finder->addMatcher(
63 implicitCastExpr(hasCastKind(CK_BitCast), isMultiLevelPointerConversion(),
64 unless(hasParent(explicitCastExpr(
65 hasDestinationType(isPointerType())))))
66 .bind("expr"),
67 this);
68 }
69
70 std::optional<TraversalKind>
getCheckTraversalKind() const71 MultiLevelImplicitPointerConversionCheck::getCheckTraversalKind() const {
72 return TK_AsIs;
73 }
74
check(const MatchFinder::MatchResult & Result)75 void MultiLevelImplicitPointerConversionCheck::check(
76 const MatchFinder::MatchResult &Result) {
77 const auto *MatchedExpr = Result.Nodes.getNodeAs<ImplicitCastExpr>("expr");
78 QualType Target = MatchedExpr->getType().getDesugaredType(*Result.Context);
79 QualType Source =
80 MatchedExpr->getSubExpr()->getType().getDesugaredType(*Result.Context);
81
82 diag(MatchedExpr->getExprLoc(), "multilevel pointer conversion from %0 to "
83 "%1, please use explicit cast")
84 << Source << Target;
85 }
86
87 } // namespace clang::tidy::bugprone
88