1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
//===- RedundantStringCStrCheck.cpp - Check for redundant c_str calls -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements a check for redundant calls of c_str() on strings.
//
//===----------------------------------------------------------------------===//
#include "RedundantStringCStrCheck.h"
#include "../utils/FixItHintUtils.h"
#include "../utils/Matchers.h"
#include "../utils/OptionsUtils.h"
#include "clang/Lex/Lexer.h"
#include "clang/Tooling/FixIt.h"
using namespace clang::ast_matchers;
namespace clang::tidy::readability {
namespace {
AST_MATCHER(MaterializeTemporaryExpr, isBoundToLValue) {
return Node.isBoundToLvalueReference();
}
} // end namespace
RedundantStringCStrCheck::RedundantStringCStrCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
StringParameterFunctions(utils::options::parseStringList(
Options.get("StringParameterFunctions", ""))) {
if (getLangOpts().CPlusPlus20)
StringParameterFunctions.push_back("::std::format");
if (getLangOpts().CPlusPlus23)
StringParameterFunctions.push_back("::std::print");
}
void RedundantStringCStrCheck::registerMatchers(
ast_matchers::MatchFinder *Finder) {
// Match expressions of type 'string' or 'string*'.
const auto StringDecl = type(hasUnqualifiedDesugaredType(recordType(
hasDeclaration(cxxRecordDecl(hasName("::std::basic_string"))))));
const auto StringExpr =
expr(anyOf(hasType(StringDecl), hasType(qualType(pointsTo(StringDecl)))));
// Match string constructor.
const auto StringConstructorExpr = expr(anyOf(
cxxConstructExpr(argumentCountIs(1),
hasDeclaration(cxxMethodDecl(hasName("basic_string")))),
cxxConstructExpr(
argumentCountIs(2),
hasDeclaration(cxxMethodDecl(hasName("basic_string"))),
// If present, the second argument is the alloc object which must not
// be present explicitly.
hasArgument(1, cxxDefaultArgExpr()))));
// Match string constructor.
const auto StringViewConstructorExpr = cxxConstructExpr(
argumentCountIs(1),
hasDeclaration(cxxMethodDecl(hasName("basic_string_view"))));
// Match a call to the string 'c_str()' method.
const auto StringCStrCallExpr =
cxxMemberCallExpr(on(StringExpr.bind("arg")),
callee(memberExpr().bind("member")),
callee(cxxMethodDecl(hasAnyName("c_str", "data"))))
.bind("call");
const auto HasRValueTempParent =
hasParent(materializeTemporaryExpr(unless(isBoundToLValue())));
// Detect redundant 'c_str()' calls through a string constructor.
// If CxxConstructExpr is the part of some CallExpr we need to
// check that matched ParamDecl of the ancestor CallExpr is not rvalue.
Finder->addMatcher(
traverse(
TK_AsIs,
cxxConstructExpr(
anyOf(StringConstructorExpr, StringViewConstructorExpr),
hasArgument(0, StringCStrCallExpr),
unless(anyOf(HasRValueTempParent, hasParent(cxxBindTemporaryExpr(
HasRValueTempParent)))))),
this);
// Detect: 's == str.c_str()' -> 's == str'
Finder->addMatcher(
cxxOperatorCallExpr(
hasAnyOverloadedOperatorName("<", ">", ">=", "<=", "!=", "==", "+"),
anyOf(allOf(hasArgument(0, StringExpr),
hasArgument(1, StringCStrCallExpr)),
allOf(hasArgument(0, StringCStrCallExpr),
hasArgument(1, StringExpr)))),
this);
// Detect: 'dst += str.c_str()' -> 'dst += str'
// Detect: 's = str.c_str()' -> 's = str'
Finder->addMatcher(
cxxOperatorCallExpr(hasAnyOverloadedOperatorName("=", "+="),
hasArgument(0, StringExpr),
hasArgument(1, StringCStrCallExpr)),
this);
// Detect: 'dst.append(str.c_str())' -> 'dst.append(str)'
Finder->addMatcher(
cxxMemberCallExpr(on(StringExpr), callee(decl(cxxMethodDecl(hasAnyName(
"append", "assign", "compare")))),
argumentCountIs(1), hasArgument(0, StringCStrCallExpr)),
this);
// Detect: 'dst.compare(p, n, str.c_str())' -> 'dst.compare(p, n, str)'
Finder->addMatcher(
cxxMemberCallExpr(on(StringExpr),
callee(decl(cxxMethodDecl(hasName("compare")))),
argumentCountIs(3), hasArgument(2, StringCStrCallExpr)),
this);
// Detect: 'dst.find(str.c_str())' -> 'dst.find(str)'
Finder->addMatcher(
cxxMemberCallExpr(on(StringExpr),
callee(decl(cxxMethodDecl(hasAnyName(
"find", "find_first_not_of", "find_first_of",
"find_last_not_of", "find_last_of", "rfind")))),
anyOf(argumentCountIs(1), argumentCountIs(2)),
hasArgument(0, StringCStrCallExpr)),
this);
// Detect: 'dst.insert(pos, str.c_str())' -> 'dst.insert(pos, str)'
Finder->addMatcher(
cxxMemberCallExpr(on(StringExpr),
callee(decl(cxxMethodDecl(hasName("insert")))),
argumentCountIs(2), hasArgument(1, StringCStrCallExpr)),
this);
// Detect redundant 'c_str()' calls through a StringRef constructor.
Finder->addMatcher(
traverse(
TK_AsIs,
cxxConstructExpr(
// Implicit constructors of these classes are overloaded
// wrt. string types and they internally make a StringRef
// referring to the argument. Passing a string directly to
// them is preferred to passing a char pointer.
hasDeclaration(cxxMethodDecl(hasAnyName(
"::llvm::StringRef::StringRef", "::llvm::Twine::Twine"))),
argumentCountIs(1),
// The only argument must have the form x.c_str() or p->c_str()
// where the method is string::c_str(). StringRef also has
// a constructor from string which is more efficient (avoids
// strlen), so we can construct StringRef from the string
// directly.
hasArgument(0, StringCStrCallExpr))),
this);
if (!StringParameterFunctions.empty()) {
// Detect redundant 'c_str()' calls in parameters passed to std::format in
// C++20 onwards and std::print in C++23 onwards.
Finder->addMatcher(
traverse(TK_AsIs,
callExpr(callee(functionDecl(matchers::matchesAnyListedName(
StringParameterFunctions))),
forEachArgumentWithParam(StringCStrCallExpr,
parmVarDecl()))),
this);
}
}
void RedundantStringCStrCheck::check(const MatchFinder::MatchResult &Result) {
const auto *Call = Result.Nodes.getNodeAs<CallExpr>("call");
const auto *Arg = Result.Nodes.getNodeAs<Expr>("arg");
const auto *Member = Result.Nodes.getNodeAs<MemberExpr>("member");
bool Arrow = Member->isArrow();
// Replace the "call" node with the "arg" node, prefixed with '*'
// if the call was using '->' rather than '.'.
std::string ArgText =
Arrow ? utils::fixit::formatDereference(*Arg, *Result.Context)
: tooling::fixit::getText(*Arg, *Result.Context).str();
if (ArgText.empty())
return;
diag(Call->getBeginLoc(), "redundant call to %0")
<< Member->getMemberDecl()
<< FixItHint::CreateReplacement(Call->getSourceRange(), ArgText);
}
} // namespace clang::tidy::readability
|
