clang-tools  11.0.0
UseEmplaceCheck.cpp
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1 //===--- UseEmplaceCheck.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 "UseEmplaceCheck.h"
10 #include "../utils/OptionsUtils.h"
11 using namespace clang::ast_matchers;
12 
13 namespace clang {
14 namespace tidy {
15 namespace modernize {
16 
17 namespace {
18 AST_MATCHER(DeclRefExpr, hasExplicitTemplateArgs) {
19  return Node.hasExplicitTemplateArgs();
20 }
21 
22 const auto DefaultContainersWithPushBack =
23  "::std::vector; ::std::list; ::std::deque";
24 const auto DefaultSmartPointers =
25  "::std::shared_ptr; ::std::unique_ptr; ::std::auto_ptr; ::std::weak_ptr";
26 const auto DefaultTupleTypes = "::std::pair; ::std::tuple";
27 const auto DefaultTupleMakeFunctions = "::std::make_pair; ::std::make_tuple";
28 } // namespace
29 
30 UseEmplaceCheck::UseEmplaceCheck(StringRef Name, ClangTidyContext *Context)
31  : ClangTidyCheck(Name, Context), IgnoreImplicitConstructors(Options.get(
32  "IgnoreImplicitConstructors", false)),
33  ContainersWithPushBack(utils::options::parseStringList(Options.get(
34  "ContainersWithPushBack", DefaultContainersWithPushBack))),
35  SmartPointers(utils::options::parseStringList(
36  Options.get("SmartPointers", DefaultSmartPointers))),
37  TupleTypes(utils::options::parseStringList(
38  Options.get("TupleTypes", DefaultTupleTypes))),
39  TupleMakeFunctions(utils::options::parseStringList(
40  Options.get("TupleMakeFunctions", DefaultTupleMakeFunctions))) {}
41 
42 void UseEmplaceCheck::registerMatchers(MatchFinder *Finder) {
43  // FIXME: Bunch of functionality that could be easily added:
44  // + add handling of `push_front` for std::forward_list, std::list
45  // and std::deque.
46  // + add handling of `push` for std::stack, std::queue, std::priority_queue
47  // + add handling of `insert` for stl associative container, but be careful
48  // because this requires special treatment (it could cause performance
49  // regression)
50  // + match for emplace calls that should be replaced with insertion
51  auto CallPushBack = cxxMemberCallExpr(
52  hasDeclaration(functionDecl(hasName("push_back"))),
53  on(hasType(cxxRecordDecl(hasAnyName(SmallVector<StringRef, 5>(
54  ContainersWithPushBack.begin(), ContainersWithPushBack.end()))))));
55 
56  // We can't replace push_backs of smart pointer because
57  // if emplacement fails (f.e. bad_alloc in vector) we will have leak of
58  // passed pointer because smart pointer won't be constructed
59  // (and destructed) as in push_back case.
60  auto IsCtorOfSmartPtr = hasDeclaration(cxxConstructorDecl(ofClass(hasAnyName(
61  SmallVector<StringRef, 5>(SmartPointers.begin(), SmartPointers.end())))));
62 
63  // Bitfields binds only to consts and emplace_back take it by universal ref.
64  auto BitFieldAsArgument = hasAnyArgument(
65  ignoringImplicit(memberExpr(hasDeclaration(fieldDecl(isBitField())))));
66 
67  // Initializer list can't be passed to universal reference.
68  auto InitializerListAsArgument = hasAnyArgument(
69  ignoringImplicit(cxxConstructExpr(isListInitialization())));
70 
71  // We could have leak of resource.
72  auto NewExprAsArgument = hasAnyArgument(ignoringImplicit(cxxNewExpr()));
73  // We would call another constructor.
74  auto ConstructingDerived =
75  hasParent(implicitCastExpr(hasCastKind(CastKind::CK_DerivedToBase)));
76 
77  // emplace_back can't access private constructor.
78  auto IsPrivateCtor = hasDeclaration(cxxConstructorDecl(isPrivate()));
79 
80  auto HasInitList = anyOf(has(ignoringImplicit(initListExpr())),
81  has(cxxStdInitializerListExpr()));
82 
83  // FIXME: Discard 0/NULL (as nullptr), static inline const data members,
84  // overloaded functions and template names.
85  auto SoughtConstructExpr =
86  cxxConstructExpr(
87  unless(anyOf(IsCtorOfSmartPtr, HasInitList, BitFieldAsArgument,
88  InitializerListAsArgument, NewExprAsArgument,
89  ConstructingDerived, IsPrivateCtor)))
90  .bind("ctor");
91  auto HasConstructExpr = has(ignoringImplicit(SoughtConstructExpr));
92 
93  auto MakeTuple = ignoringImplicit(
94  callExpr(
95  callee(expr(ignoringImplicit(declRefExpr(
96  unless(hasExplicitTemplateArgs()),
97  to(functionDecl(hasAnyName(SmallVector<StringRef, 2>(
98  TupleMakeFunctions.begin(), TupleMakeFunctions.end())))))))))
99  .bind("make"));
100 
101  // make_something can return type convertible to container's element type.
102  // Allow the conversion only on containers of pairs.
103  auto MakeTupleCtor = ignoringImplicit(cxxConstructExpr(
104  has(materializeTemporaryExpr(MakeTuple)),
105  hasDeclaration(cxxConstructorDecl(ofClass(hasAnyName(
106  SmallVector<StringRef, 2>(TupleTypes.begin(), TupleTypes.end())))))));
107 
108  auto SoughtParam = materializeTemporaryExpr(
109  anyOf(has(MakeTuple), has(MakeTupleCtor),
110  HasConstructExpr, has(cxxFunctionalCastExpr(HasConstructExpr))));
111 
112  Finder->addMatcher(
113  traverse(ast_type_traits::TK_AsIs,
114  cxxMemberCallExpr(CallPushBack, has(SoughtParam),
115  unless(isInTemplateInstantiation()))
116  .bind("call")),
117  this);
118 }
119 
120 void UseEmplaceCheck::check(const MatchFinder::MatchResult &Result) {
121  const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call");
122  const auto *CtorCall = Result.Nodes.getNodeAs<CXXConstructExpr>("ctor");
123  const auto *MakeCall = Result.Nodes.getNodeAs<CallExpr>("make");
124  assert((CtorCall || MakeCall) && "No push_back parameter matched");
125 
126  if (IgnoreImplicitConstructors && CtorCall && CtorCall->getNumArgs() >= 1 &&
127  CtorCall->getArg(0)->getSourceRange() == CtorCall->getSourceRange())
128  return;
129 
130  const auto FunctionNameSourceRange = CharSourceRange::getCharRange(
131  Call->getExprLoc(), Call->getArg(0)->getExprLoc());
132 
133  auto Diag = diag(Call->getExprLoc(), "use emplace_back instead of push_back");
134 
135  if (FunctionNameSourceRange.getBegin().isMacroID())
136  return;
137 
138  const auto *EmplacePrefix = MakeCall ? "emplace_back" : "emplace_back(";
139  Diag << FixItHint::CreateReplacement(FunctionNameSourceRange, EmplacePrefix);
140 
141  const SourceRange CallParensRange =
142  MakeCall ? SourceRange(MakeCall->getCallee()->getEndLoc(),
143  MakeCall->getRParenLoc())
144  : CtorCall->getParenOrBraceRange();
145 
146  // Finish if there is no explicit constructor call.
147  if (CallParensRange.getBegin().isInvalid())
148  return;
149 
150  const SourceLocation ExprBegin =
151  MakeCall ? MakeCall->getExprLoc() : CtorCall->getExprLoc();
152 
153  // Range for constructor name and opening brace.
154  const auto ParamCallSourceRange =
155  CharSourceRange::getTokenRange(ExprBegin, CallParensRange.getBegin());
156 
157  Diag << FixItHint::CreateRemoval(ParamCallSourceRange)
158  << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
159  CallParensRange.getEnd(), CallParensRange.getEnd()));
160 }
161 
163  Options.store(Opts, "IgnoreImplicitConstructors", IgnoreImplicitConstructors);
164  Options.store(Opts, "ContainersWithPushBack",
165  utils::options::serializeStringList(ContainersWithPushBack));
166  Options.store(Opts, "SmartPointers",
167  utils::options::serializeStringList(SmartPointers));
168  Options.store(Opts, "TupleTypes",
170  Options.store(Opts, "TupleMakeFunctions",
171  utils::options::serializeStringList(TupleMakeFunctions));
172 }
173 
174 } // namespace modernize
175 } // namespace tidy
176 } // namespace clang
clang::tidy::modernize::UseEmplaceCheck::registerMatchers
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Definition: UseEmplaceCheck.cpp:42
clang::tidy::ClangTidyCheck
Base class for all clang-tidy checks.
Definition: ClangTidyCheck.h:114
clang::tidy::modernize::UseEmplaceCheck::storeOptions
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
Definition: UseEmplaceCheck.cpp:162
UseEmplaceCheck.h
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::tidy::utils::options::serializeStringList
std::string serializeStringList(ArrayRef< std::string > Strings)
Serialize a sequence of names that can be parsed by parseStringList.
Definition: OptionsUtils.cpp:30
clang::tidy::utils::options::parseStringList
std::vector< std::string > parseStringList(StringRef Option)
Parse a semicolon separated list of strings.
Definition: OptionsUtils.cpp:18
clang::tidy::ClangTidyCheck::Options
OptionsView Options
Definition: ClangTidyCheck.h:471
clang::tidy::ClangTidyContext
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
Definition: ClangTidyDiagnosticConsumer.h:76
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
clang::tidy::ClangTidyCheck::diag
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
Definition: ClangTidyCheck.cpp:55
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:19
clang::tidy::modernize::UseEmplaceCheck::check
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
Definition: UseEmplaceCheck.cpp:120
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::ClangTidyCheck::OptionsView::store
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
Definition: ClangTidyCheck.cpp:152
clang::tidy::ClangTidyOptions::OptionMap
std::map< std::string, ClangTidyValue > OptionMap
Definition: ClangTidyOptions.h:111