clang-tools 6.0.0

RedundantSmartptrGetCheck.cpp
Go to the documentation of this file.
1 //===--- RedundantSmartptrGetCheck.cpp - clang-tidy -----------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "RedundantSmartptrGetCheck.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang {
17 namespace tidy {
18 namespace readability {
19
20 namespace {
21 internal::Matcher<Expr> callToGet(const internal::Matcher<Decl> &OnClass) {
22 return cxxMemberCallExpr(
23 on(expr(anyOf(hasType(OnClass),
24 hasType(qualType(
25 pointsTo(decl(OnClass).bind("ptr_to_ptr"))))))
26 .bind("smart_pointer")),
27 unless(callee(memberExpr(hasObjectExpression(cxxThisExpr())))),
28 callee(cxxMethodDecl(
29 hasName("get"),
30 returns(qualType(pointsTo(type().bind("getType")))))))
31 .bind("redundant_get");
32 }
33
34 void registerMatchersForGetArrowStart(MatchFinder *Finder,
35 MatchFinder::MatchCallback *Callback) {
36 const auto QuacksLikeASmartptr = recordDecl(
37 recordDecl().bind("duck_typing"),
38 has(cxxMethodDecl(hasName("operator->"),
39 returns(qualType(pointsTo(type().bind("op->Type")))))),
40 has(cxxMethodDecl(hasName("operator*"), returns(qualType(references(
41 type().bind("op*Type")))))));
42
43 // Catch 'ptr.get()->Foo()'
44 Finder->addMatcher(memberExpr(expr().bind("memberExpr"), isArrow(),
45 hasObjectExpression(ignoringImpCasts(
46 callToGet(QuacksLikeASmartptr)))),
47 Callback);
48
49 // Catch '*ptr.get()' or '*ptr->get()'
50 Finder->addMatcher(
51 unaryOperator(hasOperatorName("*"),
52 hasUnaryOperand(callToGet(QuacksLikeASmartptr))),
53 Callback);
54 }
55
56 void registerMatchersForGetEquals(MatchFinder *Finder,
57 MatchFinder::MatchCallback *Callback) {
58 // This one is harder to do with duck typing.
59 // The operator==/!= that we are looking for might be member or non-member,
60 // might be on global namespace or found by ADL, might be a template, etc.
61 // For now, lets keep a list of known standard types.
62
63 const auto IsAKnownSmartptr =
64 recordDecl(hasAnyName("::std::unique_ptr", "::std::shared_ptr"));
65
66 // Matches against nullptr.
67 Finder->addMatcher(
68 binaryOperator(anyOf(hasOperatorName("=="), hasOperatorName("!=")),
69 hasEitherOperand(ignoringImpCasts(
70 anyOf(cxxNullPtrLiteralExpr(), gnuNullExpr(),
71 integerLiteral(equals(0))))),
72 hasEitherOperand(callToGet(IsAKnownSmartptr))),
73 Callback);
74
75 // Matches against if(ptr.get())
76 Finder->addMatcher(
77 ifStmt(hasCondition(ignoringImpCasts(callToGet(IsAKnownSmartptr)))),
78 Callback);
79
80 // FIXME: Match and fix if (l.get() == r.get()).
81 }
82
83 } // namespace
84
85 void RedundantSmartptrGetCheck::registerMatchers(MatchFinder *Finder) {
86 // Only register the matchers for C++; the functionality currently does not
87 // provide any benefit to other languages, despite being benign.
88 if (!getLangOpts().CPlusPlus)
89 return;
90
91 registerMatchersForGetArrowStart(Finder, this);
92 registerMatchersForGetEquals(Finder, this);
93 }
94
95 namespace {
96 bool allReturnTypesMatch(const MatchFinder::MatchResult &Result) {
97 if (Result.Nodes.getNodeAs<Decl>("duck_typing") == nullptr)
98 return true;
99 // Verify that the types match.
100 // We can't do this on the matcher because the type nodes can be different,
101 // even though they represent the same type. This difference comes from how
102 // the type is referenced (eg. through a typedef, a type trait, etc).
103 const Type *OpArrowType =
104 Result.Nodes.getNodeAs<Type>("op->Type")->getUnqualifiedDesugaredType();
105 const Type *OpStarType =
106 Result.Nodes.getNodeAs<Type>("op*Type")->getUnqualifiedDesugaredType();
107 const Type *GetType =
108 Result.Nodes.getNodeAs<Type>("getType")->getUnqualifiedDesugaredType();
109 return OpArrowType == OpStarType && OpArrowType == GetType;
110 }
111 } // namespace
112
113 void RedundantSmartptrGetCheck::check(const MatchFinder::MatchResult &Result) {
114 if (!allReturnTypesMatch(Result))
115 return;
116
117 bool IsPtrToPtr = Result.Nodes.getNodeAs<Decl>("ptr_to_ptr") != nullptr;
118 bool IsMemberExpr = Result.Nodes.getNodeAs<Expr>("memberExpr") != nullptr;
119 const auto *GetCall = Result.Nodes.getNodeAs<Expr>("redundant_get");
120 const auto *Smartptr = Result.Nodes.getNodeAs<Expr>("smart_pointer");
121
122 if (IsPtrToPtr && IsMemberExpr) {
123 // Ignore this case (eg. Foo->get()->DoSomething());
124 return;
125 }
126
127 StringRef SmartptrText = Lexer::getSourceText(
128 CharSourceRange::getTokenRange(Smartptr->getSourceRange()),
129 *Result.SourceManager, getLangOpts());
130 // Replace foo->get() with *foo, and foo.get() with foo.
131 std::string Replacement = Twine(IsPtrToPtr ? "*" : "", SmartptrText).str();
132 diag(GetCall->getLocStart(), "redundant get() call on smart pointer")
133 << FixItHint::CreateReplacement(GetCall->getSourceRange(), Replacement);
134 }
135
136 } // namespace readability
137 } // namespace tidy
138 } // namespace clang
clang::ast_matchers
Definition: ClangTidyDiagnosticConsumer.h:27
RedundantSmartptrGetCheck.h
clang
Definition: AndroidTidyModule.cpp:28