1 //===--- RedundantSmartptrGetCheck.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 "RedundantSmartptrGetCheck.h"
10 #include "clang/ASTMatchers/ASTMatchFinder.h"
11 #include "clang/Lex/Lexer.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang {
16 namespace tidy {
17 namespace readability {
18
19 namespace {
callToGet(const internal::Matcher<Decl> & OnClass)20 internal::Matcher<Expr> callToGet(const internal::Matcher<Decl> &OnClass) {
21 return cxxMemberCallExpr(
22 on(expr(anyOf(hasType(OnClass),
23 hasType(qualType(
24 pointsTo(decl(OnClass).bind("ptr_to_ptr"))))))
25 .bind("smart_pointer")),
26 unless(callee(memberExpr(hasObjectExpression(cxxThisExpr())))),
27 callee(cxxMethodDecl(
28 hasName("get"),
29 returns(qualType(pointsTo(type().bind("getType")))))))
30 .bind("redundant_get");
31 }
32
knownSmartptr()33 internal::Matcher<Decl> knownSmartptr() {
34 return recordDecl(hasAnyName("::std::unique_ptr", "::std::shared_ptr"));
35 }
36
registerMatchersForGetArrowStart(MatchFinder * Finder,MatchFinder::MatchCallback * Callback)37 void registerMatchersForGetArrowStart(MatchFinder *Finder,
38 MatchFinder::MatchCallback *Callback) {
39 const auto QuacksLikeASmartptr = recordDecl(
40 recordDecl().bind("duck_typing"),
41 has(cxxMethodDecl(hasName("operator->"),
42 returns(qualType(pointsTo(type().bind("op->Type")))))),
43 has(cxxMethodDecl(hasName("operator*"), returns(qualType(references(
44 type().bind("op*Type")))))));
45
46 // Make sure we are not missing the known standard types.
47 const auto Smartptr = anyOf(knownSmartptr(), QuacksLikeASmartptr);
48
49 // Catch 'ptr.get()->Foo()'
50 Finder->addMatcher(
51 memberExpr(expr().bind("memberExpr"), isArrow(),
52 hasObjectExpression(ignoringImpCasts(callToGet(Smartptr)))),
53 Callback);
54
55 // Catch '*ptr.get()' or '*ptr->get()'
56 Finder->addMatcher(
57 unaryOperator(hasOperatorName("*"), hasUnaryOperand(callToGet(Smartptr))),
58 Callback);
59
60 // Catch '!ptr.get()'
61 const auto CallToGetAsBool = ignoringParenImpCasts(callToGet(
62 recordDecl(Smartptr, has(cxxConversionDecl(returns(booleanType()))))));
63 Finder->addMatcher(
64 unaryOperator(hasOperatorName("!"), hasUnaryOperand(CallToGetAsBool)),
65 Callback);
66
67 // Catch 'if(ptr.get())'
68 Finder->addMatcher(ifStmt(hasCondition(CallToGetAsBool)), Callback);
69
70 // Catch 'ptr.get() ? X : Y'
71 Finder->addMatcher(conditionalOperator(hasCondition(CallToGetAsBool)),
72 Callback);
73 }
74
registerMatchersForGetEquals(MatchFinder * Finder,MatchFinder::MatchCallback * Callback)75 void registerMatchersForGetEquals(MatchFinder *Finder,
76 MatchFinder::MatchCallback *Callback) {
77 // This one is harder to do with duck typing.
78 // The operator==/!= that we are looking for might be member or non-member,
79 // might be on global namespace or found by ADL, might be a template, etc.
80 // For now, lets keep it to the known standard types.
81
82 // Matches against nullptr.
83 Finder->addMatcher(
84 binaryOperator(anyOf(hasOperatorName("=="), hasOperatorName("!=")),
85 hasEitherOperand(ignoringImpCasts(
86 anyOf(cxxNullPtrLiteralExpr(), gnuNullExpr(),
87 integerLiteral(equals(0))))),
88 hasEitherOperand(callToGet(knownSmartptr()))),
89 Callback);
90
91 // FIXME: Match and fix if (l.get() == r.get()).
92 }
93
94 } // namespace
95
storeOptions(ClangTidyOptions::OptionMap & Opts)96 void RedundantSmartptrGetCheck::storeOptions(
97 ClangTidyOptions::OptionMap &Opts) {
98 Options.store(Opts, "IgnoreMacros", IgnoreMacros);
99 }
100
registerMatchers(MatchFinder * Finder)101 void RedundantSmartptrGetCheck::registerMatchers(MatchFinder *Finder) {
102 // Only register the matchers for C++; the functionality currently does not
103 // provide any benefit to other languages, despite being benign.
104 if (!getLangOpts().CPlusPlus)
105 return;
106
107 registerMatchersForGetArrowStart(Finder, this);
108 registerMatchersForGetEquals(Finder, this);
109 }
110
111 namespace {
allReturnTypesMatch(const MatchFinder::MatchResult & Result)112 bool allReturnTypesMatch(const MatchFinder::MatchResult &Result) {
113 if (Result.Nodes.getNodeAs<Decl>("duck_typing") == nullptr)
114 return true;
115 // Verify that the types match.
116 // We can't do this on the matcher because the type nodes can be different,
117 // even though they represent the same type. This difference comes from how
118 // the type is referenced (eg. through a typedef, a type trait, etc).
119 const Type *OpArrowType =
120 Result.Nodes.getNodeAs<Type>("op->Type")->getUnqualifiedDesugaredType();
121 const Type *OpStarType =
122 Result.Nodes.getNodeAs<Type>("op*Type")->getUnqualifiedDesugaredType();
123 const Type *GetType =
124 Result.Nodes.getNodeAs<Type>("getType")->getUnqualifiedDesugaredType();
125 return OpArrowType == OpStarType && OpArrowType == GetType;
126 }
127 } // namespace
128
check(const MatchFinder::MatchResult & Result)129 void RedundantSmartptrGetCheck::check(const MatchFinder::MatchResult &Result) {
130 if (!allReturnTypesMatch(Result))
131 return;
132
133 bool IsPtrToPtr = Result.Nodes.getNodeAs<Decl>("ptr_to_ptr") != nullptr;
134 bool IsMemberExpr = Result.Nodes.getNodeAs<Expr>("memberExpr") != nullptr;
135 const auto *GetCall = Result.Nodes.getNodeAs<Expr>("redundant_get");
136 if (GetCall->getBeginLoc().isMacroID() && IgnoreMacros)
137 return;
138
139 const auto *Smartptr = Result.Nodes.getNodeAs<Expr>("smart_pointer");
140
141 if (IsPtrToPtr && IsMemberExpr) {
142 // Ignore this case (eg. Foo->get()->DoSomething());
143 return;
144 }
145
146 StringRef SmartptrText = Lexer::getSourceText(
147 CharSourceRange::getTokenRange(Smartptr->getSourceRange()),
148 *Result.SourceManager, getLangOpts());
149 // Replace foo->get() with *foo, and foo.get() with foo.
150 std::string Replacement = Twine(IsPtrToPtr ? "*" : "", SmartptrText).str();
151 diag(GetCall->getBeginLoc(), "redundant get() call on smart pointer")
152 << FixItHint::CreateReplacement(GetCall->getSourceRange(), Replacement);
153 }
154
155 } // namespace readability
156 } // namespace tidy
157 } // namespace clang
158