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
13using namespace clang::ast_matchers;
14
15namespace clang::tidy::readability {
16
17namespace {
18internal::Matcher<Expr> callToGet(const internal::Matcher<Decl> &OnClass) {
19 return expr(
20 anyOf(cxxMemberCallExpr(
21 on(InnerMatcher: expr(anyOf(hasType(InnerMatcher: OnClass),
22 hasType(InnerMatcher: qualType(pointsTo(
23 InnerMatcher: decl(OnClass).bind(ID: "ptr_to_ptr"))))))
24 .bind(ID: "smart_pointer")),
25 unless(callee(
26 InnerMatcher: memberExpr(hasObjectExpression(InnerMatcher: cxxThisExpr())))),
27 callee(InnerMatcher: cxxMethodDecl(hasName(Name: "get"),
28 returns(InnerMatcher: qualType(pointsTo(
29 InnerMatcher: type().bind(ID: "getType"))))))),
30 cxxDependentScopeMemberExpr(
31 hasMemberName(N: "get"),
32 hasObjectExpression(
33 InnerMatcher: expr(hasType(InnerMatcher: qualType(hasCanonicalType(
34 InnerMatcher: templateSpecializationType(hasDeclaration(
35 InnerMatcher: classTemplateDecl(has(cxxRecordDecl(
36 OnClass,
37 hasMethod(InnerMatcher: cxxMethodDecl(
38 hasName(Name: "get"),
39 returns(InnerMatcher: qualType(
40 pointsTo(InnerMatcher: type().bind(
41 ID: "getType")))))))))))))))
42 .bind(ID: "smart_pointer")))))
43 .bind(ID: "redundant_get");
44}
45
46internal::Matcher<Decl> knownSmartptr() {
47 return recordDecl(hasAnyName("::std::unique_ptr", "::std::shared_ptr"));
48}
49
50void registerMatchersForGetArrowStart(MatchFinder *Finder,
51 MatchFinder::MatchCallback *Callback) {
52 const auto QuacksLikeASmartptr = recordDecl(
53 recordDecl().bind(ID: "duck_typing"),
54 has(cxxMethodDecl(hasName(Name: "operator->"),
55 returns(InnerMatcher: qualType(pointsTo(InnerMatcher: type().bind(ID: "op->Type")))))),
56 has(cxxMethodDecl(hasName(Name: "operator*"), returns(InnerMatcher: qualType(references(
57 InnerMatcher: type().bind(ID: "op*Type")))))));
58
59 // Make sure we are not missing the known standard types.
60 const auto Smartptr = anyOf(knownSmartptr(), QuacksLikeASmartptr);
61
62 // Catch 'ptr.get()->Foo()'
63 Finder->addMatcher(NodeMatch: memberExpr(expr().bind(ID: "memberExpr"), isArrow(),
64 hasObjectExpression(InnerMatcher: callToGet(OnClass: Smartptr))),
65 Action: Callback);
66
67 // Catch '*ptr.get()' or '*ptr->get()'
68 Finder->addMatcher(
69 NodeMatch: unaryOperator(hasOperatorName(Name: "*"), hasUnaryOperand(InnerMatcher: callToGet(OnClass: Smartptr))),
70 Action: Callback);
71
72 // Catch '!ptr.get()'
73 const auto CallToGetAsBool = callToGet(
74 OnClass: recordDecl(Smartptr, has(cxxConversionDecl(returns(InnerMatcher: booleanType())))));
75 Finder->addMatcher(
76 NodeMatch: unaryOperator(hasOperatorName(Name: "!"), hasUnaryOperand(InnerMatcher: CallToGetAsBool)),
77 Action: Callback);
78
79 // Catch 'if(ptr.get())'
80 Finder->addMatcher(NodeMatch: ifStmt(hasCondition(InnerMatcher: CallToGetAsBool)), Action: Callback);
81
82 // Catch 'ptr.get() ? X : Y'
83 Finder->addMatcher(NodeMatch: conditionalOperator(hasCondition(InnerMatcher: CallToGetAsBool)),
84 Action: Callback);
85
86 Finder->addMatcher(NodeMatch: cxxDependentScopeMemberExpr(hasObjectExpression(
87 InnerMatcher: callExpr(has(callToGet(OnClass: Smartptr))).bind(ID: "obj"))),
88 Action: Callback);
89}
90
91void registerMatchersForGetEquals(MatchFinder *Finder,
92 MatchFinder::MatchCallback *Callback) {
93 // This one is harder to do with duck typing.
94 // The operator==/!= that we are looking for might be member or non-member,
95 // might be on global namespace or found by ADL, might be a template, etc.
96 // For now, lets keep it to the known standard types.
97
98 // Matches against nullptr.
99 Finder->addMatcher(
100 NodeMatch: binaryOperator(hasAnyOperatorName("==", "!="),
101 hasOperands(Matcher1: anyOf(cxxNullPtrLiteralExpr(), gnuNullExpr(),
102 integerLiteral(equals(Value: 0))),
103 Matcher2: callToGet(OnClass: knownSmartptr()))),
104 Action: Callback);
105
106 // FIXME: Match and fix if (l.get() == r.get()).
107}
108
109} // namespace
110
111void RedundantSmartptrGetCheck::storeOptions(
112 ClangTidyOptions::OptionMap &Opts) {
113 Options.store(Options&: Opts, LocalName: "IgnoreMacros", Value: IgnoreMacros);
114}
115
116void RedundantSmartptrGetCheck::registerMatchers(MatchFinder *Finder) {
117 registerMatchersForGetArrowStart(Finder, Callback: this);
118 registerMatchersForGetEquals(Finder, Callback: this);
119}
120
121namespace {
122bool allReturnTypesMatch(const MatchFinder::MatchResult &Result) {
123 if (Result.Nodes.getNodeAs<Decl>(ID: "duck_typing") == nullptr)
124 return true;
125 // Verify that the types match.
126 // We can't do this on the matcher because the type nodes can be different,
127 // even though they represent the same type. This difference comes from how
128 // the type is referenced (eg. through a typedef, a type trait, etc).
129 const Type *OpArrowType =
130 Result.Nodes.getNodeAs<Type>(ID: "op->Type")->getUnqualifiedDesugaredType();
131 const Type *OpStarType =
132 Result.Nodes.getNodeAs<Type>(ID: "op*Type")->getUnqualifiedDesugaredType();
133 const Type *GetType =
134 Result.Nodes.getNodeAs<Type>(ID: "getType")->getUnqualifiedDesugaredType();
135 return OpArrowType == OpStarType && OpArrowType == GetType;
136}
137} // namespace
138
139void RedundantSmartptrGetCheck::check(const MatchFinder::MatchResult &Result) {
140 if (!allReturnTypesMatch(Result))
141 return;
142
143 bool IsPtrToPtr = Result.Nodes.getNodeAs<Decl>(ID: "ptr_to_ptr") != nullptr;
144 bool IsMemberExpr = Result.Nodes.getNodeAs<Expr>(ID: "memberExpr") != nullptr;
145 const auto *GetCall = Result.Nodes.getNodeAs<Expr>(ID: "redundant_get");
146 if (GetCall->getBeginLoc().isMacroID() && IgnoreMacros)
147 return;
148
149 const auto *Smartptr = Result.Nodes.getNodeAs<Expr>(ID: "smart_pointer");
150
151 if (IsPtrToPtr && IsMemberExpr) {
152 // Ignore this case (eg. Foo->get()->DoSomething());
153 return;
154 }
155
156 auto SR = GetCall->getSourceRange();
157 // CXXDependentScopeMemberExpr source range does not include parens
158 // Extend the source range of the get call to account for them.
159 if (isa<CXXDependentScopeMemberExpr>(Val: GetCall))
160 SR.setEnd(Lexer::getLocForEndOfToken(Loc: SR.getEnd(), Offset: 0, SM: *Result.SourceManager,
161 LangOpts: getLangOpts())
162 .getLocWithOffset(1));
163
164 StringRef SmartptrText = Lexer::getSourceText(
165 Range: CharSourceRange::getTokenRange(Smartptr->getSourceRange()),
166 SM: *Result.SourceManager, LangOpts: getLangOpts());
167 // Replace foo->get() with *foo, and foo.get() with foo.
168 std::string Replacement = Twine(IsPtrToPtr ? "*" : "", SmartptrText).str();
169 diag(GetCall->getBeginLoc(), "redundant get() call on smart pointer")
170 << FixItHint::CreateReplacement(SR, Replacement);
171}
172
173} // namespace clang::tidy::readability
174

source code of clang-tools-extra/clang-tidy/readability/RedundantSmartptrGetCheck.cpp