clang-tools 19.0.0git
UnusedReturnValueCheck.cpp
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1//===--- UnusedReturnValueCheck.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
10#include "../utils/Matchers.h"
11#include "../utils/OptionsUtils.h"
12#include "clang/AST/ASTContext.h"
13#include "clang/ASTMatchers/ASTMatchFinder.h"
14
15using namespace clang::ast_matchers;
16using namespace clang::ast_matchers::internal;
17
18namespace clang::tidy::bugprone {
19
20namespace {
21
22// Matches functions that are instantiated from a class template member function
23// matching InnerMatcher. Functions not instantiated from a class template
24// member function are matched directly with InnerMatcher.
25AST_MATCHER_P(FunctionDecl, isInstantiatedFrom, Matcher<FunctionDecl>,
26 InnerMatcher) {
27 FunctionDecl *InstantiatedFrom = Node.getInstantiatedFromMemberFunction();
28 return InnerMatcher.matches(InstantiatedFrom ? *InstantiatedFrom : Node,
29 Finder, Builder);
30}
31} // namespace
32
34 ClangTidyContext *Context)
35 : ClangTidyCheck(Name, Context),
36 CheckedFunctions(Options.get("CheckedFunctions",
37 "::std::async;"
38 "::std::launder;"
39 "::std::remove;"
40 "::std::remove_if;"
41 "::std::unique;"
42 "::std::unique_ptr::release;"
43 "::std::basic_string::empty;"
44 "::std::vector::empty;"
45 "::std::back_inserter;"
46 "::std::distance;"
47 "::std::find;"
48 "::std::find_if;"
49 "::std::inserter;"
50 "::std::lower_bound;"
51 "::std::make_pair;"
52 "::std::map::count;"
53 "::std::map::find;"
54 "::std::map::lower_bound;"
55 "::std::multimap::equal_range;"
56 "::std::multimap::upper_bound;"
57 "::std::set::count;"
58 "::std::set::find;"
59 "::std::setfill;"
60 "::std::setprecision;"
61 "::std::setw;"
62 "::std::upper_bound;"
63 "::std::vector::at;"
64 // C standard library
65 "::bsearch;"
66 "::ferror;"
67 "::feof;"
68 "::isalnum;"
69 "::isalpha;"
70 "::isblank;"
71 "::iscntrl;"
72 "::isdigit;"
73 "::isgraph;"
74 "::islower;"
75 "::isprint;"
76 "::ispunct;"
77 "::isspace;"
78 "::isupper;"
79 "::iswalnum;"
80 "::iswprint;"
81 "::iswspace;"
82 "::isxdigit;"
83 "::memchr;"
84 "::memcmp;"
85 "::strcmp;"
86 "::strcoll;"
87 "::strncmp;"
88 "::strpbrk;"
89 "::strrchr;"
90 "::strspn;"
91 "::strstr;"
92 "::wcscmp;"
93 // POSIX
94 "::access;"
95 "::bind;"
96 "::connect;"
97 "::difftime;"
98 "::dlsym;"
99 "::fnmatch;"
100 "::getaddrinfo;"
101 "::getopt;"
102 "::htonl;"
103 "::htons;"
104 "::iconv_open;"
105 "::inet_addr;"
106 "::isascii;"
107 "::isatty;"
108 "::mmap;"
109 "::newlocale;"
110 "::openat;"
111 "::pathconf;"
112 "::pthread_equal;"
113 "::pthread_getspecific;"
114 "::pthread_mutex_trylock;"
115 "::readdir;"
116 "::readlink;"
117 "::recvmsg;"
118 "::regexec;"
119 "::scandir;"
120 "::semget;"
121 "::setjmp;"
122 "::shm_open;"
123 "::shmget;"
124 "::sigismember;"
125 "::strcasecmp;"
126 "::strsignal;"
127 "::ttyname")),
128 CheckedReturnTypes(utils::options::parseStringList(
129 Options.get("CheckedReturnTypes", "::std::error_code;"
130 "::std::error_condition;"
131 "::std::errc;"
132 "::std::expected;"
133 "::boost::system::error_code"))),
134 AllowCastToVoid(Options.get("AllowCastToVoid", false)) {}
135
136UnusedReturnValueCheck::UnusedReturnValueCheck(llvm::StringRef Name,
137 ClangTidyContext *Context,
138 std::string CheckedFunctions)
139 : UnusedReturnValueCheck(Name, Context, std::move(CheckedFunctions), {},
140 false) {}
141
142UnusedReturnValueCheck::UnusedReturnValueCheck(
143 llvm::StringRef Name, ClangTidyContext *Context,
144 std::string CheckedFunctions, std::vector<StringRef> CheckedReturnTypes,
145 bool AllowCastToVoid)
146 : ClangTidyCheck(Name, Context),
147 CheckedFunctions(std::move(CheckedFunctions)),
148 CheckedReturnTypes(std::move(CheckedReturnTypes)),
149 AllowCastToVoid(AllowCastToVoid) {}
150
151void UnusedReturnValueCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
152 Options.store(Opts, "CheckedFunctions", CheckedFunctions);
153 Options.store(Opts, "CheckedReturnTypes",
154 utils::options::serializeStringList(CheckedReturnTypes));
155 Options.store(Opts, "AllowCastToVoid", AllowCastToVoid);
156}
157
158void UnusedReturnValueCheck::registerMatchers(MatchFinder *Finder) {
159 auto FunVec = utils::options::parseStringList(CheckedFunctions);
160
161 auto MatchedDirectCallExpr =
162 expr(callExpr(callee(functionDecl(
163 // Don't match void overloads of checked functions.
164 unless(returns(voidType())),
165 anyOf(isInstantiatedFrom(hasAnyName(FunVec)),
166 returns(hasCanonicalType(hasDeclaration(
167 namedDecl(matchers::matchesAnyListedName(
168 CheckedReturnTypes)))))))))
169 .bind("match"));
170
171 auto CheckCastToVoid =
172 AllowCastToVoid ? castExpr(unless(hasCastKind(CK_ToVoid))) : castExpr();
173 auto MatchedCallExpr = expr(
174 anyOf(MatchedDirectCallExpr,
175 explicitCastExpr(unless(cxxFunctionalCastExpr()), CheckCastToVoid,
176 hasSourceExpression(MatchedDirectCallExpr))));
177
178 auto UnusedInCompoundStmt =
179 compoundStmt(forEach(MatchedCallExpr),
180 // The checker can't currently differentiate between the
181 // return statement and other statements inside GNU statement
182 // expressions, so disable the checker inside them to avoid
183 // false positives.
184 unless(hasParent(stmtExpr())));
185 auto UnusedInIfStmt =
186 ifStmt(eachOf(hasThen(MatchedCallExpr), hasElse(MatchedCallExpr)));
187 auto UnusedInWhileStmt = whileStmt(hasBody(MatchedCallExpr));
188 auto UnusedInDoStmt = doStmt(hasBody(MatchedCallExpr));
189 auto UnusedInForStmt =
190 forStmt(eachOf(hasLoopInit(MatchedCallExpr),
191 hasIncrement(MatchedCallExpr), hasBody(MatchedCallExpr)));
192 auto UnusedInRangeForStmt = cxxForRangeStmt(hasBody(MatchedCallExpr));
193 auto UnusedInCaseStmt = switchCase(forEach(MatchedCallExpr));
194
195 Finder->addMatcher(
196 stmt(anyOf(UnusedInCompoundStmt, UnusedInIfStmt, UnusedInWhileStmt,
197 UnusedInDoStmt, UnusedInForStmt, UnusedInRangeForStmt,
198 UnusedInCaseStmt)),
199 this);
200}
201
202void UnusedReturnValueCheck::check(const MatchFinder::MatchResult &Result) {
203 if (const auto *Matched = Result.Nodes.getNodeAs<CallExpr>("match")) {
204 diag(Matched->getBeginLoc(),
205 "the value returned by this function should not be disregarded; "
206 "neglecting it may lead to errors")
207 << Matched->getSourceRange();
208
209 if (!AllowCastToVoid)
210 return;
211
212 diag(Matched->getBeginLoc(),
213 "cast the expression to void to silence this warning",
214 DiagnosticIDs::Note);
215 }
216}
217
218} // namespace clang::tidy::bugprone
llvm::SmallString< 256U > Name
CodeCompletionBuilder Builder
::clang::DynTypedNode Node
UnusedReturnValueCheck(StringRef Name, ClangTidyContext *Context)
AST_MATCHER_P(FunctionDecl, parameterCountGE, unsigned, N)
Matches functions that have at least the specified amount of parameters.
std::vector< StringRef > parseStringList(StringRef Option)
Parse a semicolon separated list of strings.
llvm::StringMap< ClangTidyValue > OptionMap