clang-tools  11.0.0
DeclRefExprUtils.cpp
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1 //===--- DeclRefExprUtils.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 "DeclRefExprUtils.h"
10 #include "Matchers.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/DeclCXX.h"
13 #include "clang/ASTMatchers/ASTMatchFinder.h"
14 
15 namespace clang {
16 namespace tidy {
17 namespace utils {
18 namespace decl_ref_expr {
19 
20 using namespace ::clang::ast_matchers;
21 using llvm::SmallPtrSet;
22 
23 namespace {
24 
25 template <typename S> bool isSetDifferenceEmpty(const S &S1, const S &S2) {
26  for (auto E : S1)
27  if (S2.count(E) == 0)
28  return false;
29  return true;
30 }
31 
32 // Extracts all Nodes keyed by ID from Matches and inserts them into Nodes.
33 template <typename Node>
34 void extractNodesByIdTo(ArrayRef<BoundNodes> Matches, StringRef ID,
35  SmallPtrSet<const Node *, 16> &Nodes) {
36  for (const auto &Match : Matches)
37  Nodes.insert(Match.getNodeAs<Node>(ID));
38 }
39 
40 } // namespace
41 
42 // Finds all DeclRefExprs where a const method is called on VarDecl or VarDecl
43 // is the a const reference or value argument to a CallExpr or CXXConstructExpr.
44 SmallPtrSet<const DeclRefExpr *, 16>
45 constReferenceDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt,
46  ASTContext &Context) {
47  auto DeclRefToVar =
48  declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef");
49  auto ConstMethodCallee = callee(cxxMethodDecl(isConst()));
50  // Match method call expressions where the variable is referenced as the this
51  // implicit object argument and opertor call expression for member operators
52  // where the variable is the 0-th argument.
53  auto Matches = match(
54  findAll(expr(anyOf(cxxMemberCallExpr(ConstMethodCallee, on(DeclRefToVar)),
55  cxxOperatorCallExpr(ConstMethodCallee,
56  hasArgument(0, DeclRefToVar))))),
57  Stmt, Context);
58  SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
59  extractNodesByIdTo(Matches, "declRef", DeclRefs);
60  auto ConstReferenceOrValue =
61  qualType(anyOf(referenceType(pointee(qualType(isConstQualified()))),
62  unless(anyOf(referenceType(), pointerType()))));
63  auto UsedAsConstRefOrValueArg = forEachArgumentWithParam(
64  DeclRefToVar, parmVarDecl(hasType(ConstReferenceOrValue)));
65  Matches = match(findAll(callExpr(UsedAsConstRefOrValueArg)), Stmt, Context);
66  extractNodesByIdTo(Matches, "declRef", DeclRefs);
67  Matches =
68  match(findAll(cxxConstructExpr(UsedAsConstRefOrValueArg)), Stmt, Context);
69  extractNodesByIdTo(Matches, "declRef", DeclRefs);
70  return DeclRefs;
71 }
72 
73 bool isOnlyUsedAsConst(const VarDecl &Var, const Stmt &Stmt,
74  ASTContext &Context) {
75  // Collect all DeclRefExprs to the loop variable and all CallExprs and
76  // CXXConstructExprs where the loop variable is used as argument to a const
77  // reference parameter.
78  // If the difference is empty it is safe for the loop variable to be a const
79  // reference.
80  auto AllDeclRefs = allDeclRefExprs(Var, Stmt, Context);
81  auto ConstReferenceDeclRefs = constReferenceDeclRefExprs(Var, Stmt, Context);
82  return isSetDifferenceEmpty(AllDeclRefs, ConstReferenceDeclRefs);
83 }
84 
85 SmallPtrSet<const DeclRefExpr *, 16>
86 allDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt, ASTContext &Context) {
87  auto Matches = match(
88  findAll(declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef")),
89  Stmt, Context);
90  SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
91  extractNodesByIdTo(Matches, "declRef", DeclRefs);
92  return DeclRefs;
93 }
94 
95 SmallPtrSet<const DeclRefExpr *, 16>
96 allDeclRefExprs(const VarDecl &VarDecl, const Decl &Decl, ASTContext &Context) {
97  auto Matches = match(
98  decl(forEachDescendant(
99  declRefExpr(to(varDecl(equalsNode(&VarDecl)))).bind("declRef"))),
100  Decl, Context);
101  SmallPtrSet<const DeclRefExpr *, 16> DeclRefs;
102  extractNodesByIdTo(Matches, "declRef", DeclRefs);
103  return DeclRefs;
104 }
105 
106 bool isCopyConstructorArgument(const DeclRefExpr &DeclRef, const Decl &Decl,
107  ASTContext &Context) {
108  auto UsedAsConstRefArg = forEachArgumentWithParam(
109  declRefExpr(equalsNode(&DeclRef)),
110  parmVarDecl(hasType(matchers::isReferenceToConst())));
111  auto Matches = match(
112  decl(hasDescendant(
113  cxxConstructExpr(UsedAsConstRefArg, hasDeclaration(cxxConstructorDecl(
114  isCopyConstructor())))
115  .bind("constructExpr"))),
116  Decl, Context);
117  return !Matches.empty();
118 }
119 
120 bool isCopyAssignmentArgument(const DeclRefExpr &DeclRef, const Decl &Decl,
121  ASTContext &Context) {
122  auto UsedAsConstRefArg = forEachArgumentWithParam(
123  declRefExpr(equalsNode(&DeclRef)),
124  parmVarDecl(hasType(matchers::isReferenceToConst())));
125  auto Matches = match(
126  decl(hasDescendant(
127  cxxOperatorCallExpr(UsedAsConstRefArg, hasOverloadedOperatorName("="),
128  callee(cxxMethodDecl(isCopyAssignmentOperator())))
129  .bind("operatorCallExpr"))),
130  Decl, Context);
131  return !Matches.empty();
132 }
133 
134 } // namespace decl_ref_expr
135 } // namespace utils
136 } // namespace tidy
137 } // namespace clang
clang::tidy::utils::decl_ref_expr::allDeclRefExprs
SmallPtrSet< const DeclRefExpr *, 16 > allDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt, ASTContext &Context)
Returns set of all DeclRefExprs to VarDecl within Stmt.
Definition: DeclRefExprUtils.cpp:86
Matchers.h
E
const Expr * E
Definition: AvoidBindCheck.cpp:88
DeclRefExprUtils.h
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::clangd::match
std::vector< std::string > match(const SymbolIndex &I, const FuzzyFindRequest &Req, bool *Incomplete)
Definition: TestIndex.cpp:94
Decl
const FunctionDecl * Decl
Definition: AvoidBindCheck.cpp:100
clang::tidy::utils::decl_ref_expr::isCopyAssignmentArgument
bool isCopyAssignmentArgument(const DeclRefExpr &DeclRef, const Decl &Decl, ASTContext &Context)
Returns true if DeclRefExpr is the argument of a copy-assignment operator CallExpr within Decl.
Definition: DeclRefExprUtils.cpp:120
clang::tidy::utils::decl_ref_expr::constReferenceDeclRefExprs
SmallPtrSet< const DeclRefExpr *, 16 > constReferenceDeclRefExprs(const VarDecl &VarDecl, const Stmt &Stmt, ASTContext &Context)
Returns set of all DeclRefExprs to VarDecl within Stmt where VarDecl is guaranteed to be accessed in ...
Definition: DeclRefExprUtils.cpp:45
clang::tidy::utils::decl_ref_expr::isCopyConstructorArgument
bool isCopyConstructorArgument(const DeclRefExpr &DeclRef, const Decl &Decl, ASTContext &Context)
Returns true if DeclRefExpr is the argument of a copy-constructor call expression within Decl.
Definition: DeclRefExprUtils.cpp:106
DeclRef
const DeclRefExpr * DeclRef
Definition: UseAfterMoveCheck.cpp:50
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
clang::tidy::utils::decl_ref_expr::isOnlyUsedAsConst
bool isOnlyUsedAsConst(const VarDecl &Var, const Stmt &Stmt, ASTContext &Context)
Returns true if all DeclRefExpr to the variable within Stmt do not modify it.
Definition: DeclRefExprUtils.cpp:73