1 //===--- DanglingHandleCheck.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 "DanglingHandleCheck.h"
10 #include "../utils/Matchers.h"
11 #include "../utils/OptionsUtils.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14
15 using namespace clang::ast_matchers;
16 using namespace clang::tidy::matchers;
17
18 namespace clang {
19 namespace tidy {
20 namespace bugprone {
21
22 namespace {
23
24 ast_matchers::internal::BindableMatcher<Stmt>
handleFrom(const ast_matchers::internal::Matcher<RecordDecl> & IsAHandle,const ast_matchers::internal::Matcher<Expr> & Arg)25 handleFrom(const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle,
26 const ast_matchers::internal::Matcher<Expr> &Arg) {
27 return expr(
28 anyOf(cxxConstructExpr(hasDeclaration(cxxMethodDecl(ofClass(IsAHandle))),
29 hasArgument(0, Arg)),
30 cxxMemberCallExpr(hasType(cxxRecordDecl(IsAHandle)),
31 callee(memberExpr(member(cxxConversionDecl()))),
32 on(Arg))));
33 }
34
handleFromTemporaryValue(const ast_matchers::internal::Matcher<RecordDecl> & IsAHandle)35 ast_matchers::internal::Matcher<Stmt> handleFromTemporaryValue(
36 const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle) {
37 // If a ternary operator returns a temporary value, then both branches hold a
38 // temporary value. If one of them is not a temporary then it must be copied
39 // into one to satisfy the type of the operator.
40 const auto TemporaryTernary =
41 conditionalOperator(hasTrueExpression(cxxBindTemporaryExpr()),
42 hasFalseExpression(cxxBindTemporaryExpr()));
43
44 return handleFrom(IsAHandle, anyOf(cxxBindTemporaryExpr(), TemporaryTernary));
45 }
46
isASequence()47 ast_matchers::internal::Matcher<RecordDecl> isASequence() {
48 return hasAnyName("::std::deque", "::std::forward_list", "::std::list",
49 "::std::vector");
50 }
51
isASet()52 ast_matchers::internal::Matcher<RecordDecl> isASet() {
53 return hasAnyName("::std::set", "::std::multiset", "::std::unordered_set",
54 "::std::unordered_multiset");
55 }
56
isAMap()57 ast_matchers::internal::Matcher<RecordDecl> isAMap() {
58 return hasAnyName("::std::map", "::std::multimap", "::std::unordered_map",
59 "::std::unordered_multimap");
60 }
61
makeContainerMatcher(const ast_matchers::internal::Matcher<RecordDecl> & IsAHandle)62 ast_matchers::internal::BindableMatcher<Stmt> makeContainerMatcher(
63 const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle) {
64 // This matcher could be expanded to detect:
65 // - Constructors: eg. vector<string_view>(3, string("A"));
66 // - emplace*(): This requires a different logic to determine that
67 // the conversion will happen inside the container.
68 // - map's insert: This requires detecting that the pair conversion triggers
69 // the bug. A little more complicated than what we have now.
70 return callExpr(
71 hasAnyArgument(
72 ignoringParenImpCasts(handleFromTemporaryValue(IsAHandle))),
73 anyOf(
74 // For sequences: assign, push_back, resize.
75 cxxMemberCallExpr(
76 callee(functionDecl(hasAnyName("assign", "push_back", "resize"))),
77 on(expr(hasType(hasUnqualifiedDesugaredType(
78 recordType(hasDeclaration(recordDecl(isASequence())))))))),
79 // For sequences and sets: insert.
80 cxxMemberCallExpr(callee(functionDecl(hasName("insert"))),
81 on(expr(hasType(hasUnqualifiedDesugaredType(
82 recordType(hasDeclaration(recordDecl(
83 anyOf(isASequence(), isASet()))))))))),
84 // For maps: operator[].
85 cxxOperatorCallExpr(callee(cxxMethodDecl(ofClass(isAMap()))),
86 hasOverloadedOperatorName("[]"))));
87 }
88
89 } // anonymous namespace
90
DanglingHandleCheck(StringRef Name,ClangTidyContext * Context)91 DanglingHandleCheck::DanglingHandleCheck(StringRef Name,
92 ClangTidyContext *Context)
93 : ClangTidyCheck(Name, Context),
94 HandleClasses(utils::options::parseStringList(Options.get(
95 "HandleClasses",
96 "std::basic_string_view;std::experimental::basic_string_view"))),
97 IsAHandle(cxxRecordDecl(hasAnyName(HandleClasses)).bind("handle")) {}
98
storeOptions(ClangTidyOptions::OptionMap & Opts)99 void DanglingHandleCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
100 Options.store(Opts, "HandleClasses",
101 utils::options::serializeStringList(HandleClasses));
102 }
103
registerMatchersForVariables(MatchFinder * Finder)104 void DanglingHandleCheck::registerMatchersForVariables(MatchFinder *Finder) {
105 const auto ConvertedHandle = handleFromTemporaryValue(IsAHandle);
106
107 // Find 'Handle foo(ReturnsAValue());'
108 Finder->addMatcher(
109 varDecl(hasType(hasUnqualifiedDesugaredType(
110 recordType(hasDeclaration(cxxRecordDecl(IsAHandle))))),
111 hasInitializer(
112 exprWithCleanups(has(ignoringParenImpCasts(ConvertedHandle)))
113 .bind("bad_stmt"))),
114 this);
115
116 // Find 'Handle foo = ReturnsAValue();'
117 Finder->addMatcher(
118 traverse(TK_AsIs,
119 varDecl(hasType(hasUnqualifiedDesugaredType(recordType(
120 hasDeclaration(cxxRecordDecl(IsAHandle))))),
121 unless(parmVarDecl()),
122 hasInitializer(exprWithCleanups(
123 has(ignoringParenImpCasts(handleFrom(
124 IsAHandle, ConvertedHandle))))
125 .bind("bad_stmt")))),
126 this);
127 // Find 'foo = ReturnsAValue(); // foo is Handle'
128 Finder->addMatcher(
129 traverse(TK_AsIs,
130 cxxOperatorCallExpr(callee(cxxMethodDecl(ofClass(IsAHandle))),
131 hasOverloadedOperatorName("="),
132 hasArgument(1, ConvertedHandle))
133 .bind("bad_stmt")),
134 this);
135
136 // Container insertions that will dangle.
137 Finder->addMatcher(
138 traverse(TK_AsIs, makeContainerMatcher(IsAHandle).bind("bad_stmt")),
139 this);
140 }
141
registerMatchersForReturn(MatchFinder * Finder)142 void DanglingHandleCheck::registerMatchersForReturn(MatchFinder *Finder) {
143 // Return a local.
144 Finder->addMatcher(
145 traverse(
146 TK_AsIs,
147 returnStmt(
148 // The AST contains two constructor calls:
149 // 1. Value to Handle conversion.
150 // 2. Handle copy construction.
151 // We have to match both.
152 has(ignoringImplicit(handleFrom(
153 IsAHandle,
154 handleFrom(IsAHandle,
155 declRefExpr(to(varDecl(
156 // Is function scope ...
157 hasAutomaticStorageDuration(),
158 // ... and it is a local array or Value.
159 anyOf(hasType(arrayType()),
160 hasType(hasUnqualifiedDesugaredType(
161 recordType(hasDeclaration(recordDecl(
162 unless(IsAHandle)))))))))))))),
163 // Temporary fix for false positives inside lambdas.
164 unless(hasAncestor(lambdaExpr())))
165 .bind("bad_stmt")),
166 this);
167
168 // Return a temporary.
169 Finder->addMatcher(
170 traverse(
171 TK_AsIs,
172 returnStmt(has(exprWithCleanups(has(ignoringParenImpCasts(handleFrom(
173 IsAHandle, handleFromTemporaryValue(IsAHandle)))))))
174 .bind("bad_stmt")),
175 this);
176 }
177
registerMatchers(MatchFinder * Finder)178 void DanglingHandleCheck::registerMatchers(MatchFinder *Finder) {
179 registerMatchersForVariables(Finder);
180 registerMatchersForReturn(Finder);
181 }
182
check(const MatchFinder::MatchResult & Result)183 void DanglingHandleCheck::check(const MatchFinder::MatchResult &Result) {
184 auto *Handle = Result.Nodes.getNodeAs<CXXRecordDecl>("handle");
185 diag(Result.Nodes.getNodeAs<Stmt>("bad_stmt")->getBeginLoc(),
186 "%0 outlives its value")
187 << Handle->getQualifiedNameAsString();
188 }
189
190 } // namespace bugprone
191 } // namespace tidy
192 } // namespace clang
193