1 //===--- StringFindStartswithCheck.cc - clang-tidy---------------*- C++ -*-===//
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 "StringFindStartswithCheck.h"
10
11 #include "../utils/OptionsUtils.h"
12 #include "clang/AST/ASTContext.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 #include "clang/Frontend/CompilerInstance.h"
15 #include "clang/Lex/Lexer.h"
16 #include "clang/Lex/Preprocessor.h"
17
18 using namespace clang::ast_matchers;
19
20 namespace clang::tidy::abseil {
21
22 const auto DefaultStringLikeClasses =
23 "::std::basic_string;::std::basic_string_view";
24
StringFindStartswithCheck(StringRef Name,ClangTidyContext * Context)25 StringFindStartswithCheck::StringFindStartswithCheck(StringRef Name,
26 ClangTidyContext *Context)
27 : ClangTidyCheck(Name, Context),
28 StringLikeClasses(utils::options::parseStringList(
29 Options.get("StringLikeClasses", DefaultStringLikeClasses))),
30 IncludeInserter(Options.getLocalOrGlobal("IncludeStyle",
31 utils::IncludeSorter::IS_LLVM),
32 areDiagsSelfContained()),
33 AbseilStringsMatchHeader(
34 Options.get("AbseilStringsMatchHeader", "absl/strings/match.h")) {}
35
registerMatchers(MatchFinder * Finder)36 void StringFindStartswithCheck::registerMatchers(MatchFinder *Finder) {
37 auto ZeroLiteral = integerLiteral(equals(0));
38 auto StringClassMatcher = cxxRecordDecl(hasAnyName(StringLikeClasses));
39 auto StringType = hasUnqualifiedDesugaredType(
40 recordType(hasDeclaration(StringClassMatcher)));
41
42 auto StringFind = cxxMemberCallExpr(
43 // .find()-call on a string...
44 callee(cxxMethodDecl(hasName("find")).bind("findfun")),
45 on(hasType(StringType)),
46 // ... with some search expression ...
47 hasArgument(0, expr().bind("needle")),
48 // ... and either "0" as second argument or the default argument (also 0).
49 anyOf(hasArgument(1, ZeroLiteral), hasArgument(1, cxxDefaultArgExpr())));
50
51 Finder->addMatcher(
52 // Match [=!]= with a zero on one side and a string.find on the other.
53 binaryOperator(
54 hasAnyOperatorName("==", "!="),
55 hasOperands(ignoringParenImpCasts(ZeroLiteral),
56 ignoringParenImpCasts(StringFind.bind("findexpr"))))
57 .bind("expr"),
58 this);
59
60 auto StringRFind = cxxMemberCallExpr(
61 // .rfind()-call on a string...
62 callee(cxxMethodDecl(hasName("rfind")).bind("findfun")),
63 on(hasType(StringType)),
64 // ... with some search expression ...
65 hasArgument(0, expr().bind("needle")),
66 // ... and "0" as second argument.
67 hasArgument(1, ZeroLiteral));
68
69 Finder->addMatcher(
70 // Match [=!]= with either a zero or npos on one side and a string.rfind
71 // on the other.
72 binaryOperator(
73 hasAnyOperatorName("==", "!="),
74 hasOperands(ignoringParenImpCasts(ZeroLiteral),
75 ignoringParenImpCasts(StringRFind.bind("findexpr"))))
76 .bind("expr"),
77 this);
78 }
79
check(const MatchFinder::MatchResult & Result)80 void StringFindStartswithCheck::check(const MatchFinder::MatchResult &Result) {
81 const ASTContext &Context = *Result.Context;
82 const SourceManager &Source = Context.getSourceManager();
83
84 // Extract matching (sub)expressions
85 const auto *ComparisonExpr = Result.Nodes.getNodeAs<BinaryOperator>("expr");
86 assert(ComparisonExpr != nullptr);
87 const auto *Needle = Result.Nodes.getNodeAs<Expr>("needle");
88 assert(Needle != nullptr);
89 const Expr *Haystack = Result.Nodes.getNodeAs<CXXMemberCallExpr>("findexpr")
90 ->getImplicitObjectArgument();
91 assert(Haystack != nullptr);
92 const auto *FindFun = Result.Nodes.getNodeAs<CXXMethodDecl>("findfun");
93 assert(FindFun != nullptr);
94
95 bool Rev = FindFun->getName().contains("rfind");
96
97 if (ComparisonExpr->getBeginLoc().isMacroID())
98 return;
99
100 // Get the source code blocks (as characters) for both the string object
101 // and the search expression
102 const StringRef NeedleExprCode = Lexer::getSourceText(
103 CharSourceRange::getTokenRange(Needle->getSourceRange()), Source,
104 Context.getLangOpts());
105 const StringRef HaystackExprCode = Lexer::getSourceText(
106 CharSourceRange::getTokenRange(Haystack->getSourceRange()), Source,
107 Context.getLangOpts());
108
109 // Create the StartsWith string, negating if comparison was "!=".
110 bool Neg = ComparisonExpr->getOpcode() == BO_NE;
111
112 // Create the warning message and a FixIt hint replacing the original expr.
113 auto Diagnostic =
114 diag(ComparisonExpr->getBeginLoc(),
115 "use %select{absl::StartsWith|!absl::StartsWith}0 "
116 "instead of %select{find()|rfind()}1 %select{==|!=}0 0")
117 << Neg << Rev;
118
119 Diagnostic << FixItHint::CreateReplacement(
120 ComparisonExpr->getSourceRange(),
121 ((Neg ? "!absl::StartsWith(" : "absl::StartsWith(") + HaystackExprCode +
122 ", " + NeedleExprCode + ")")
123 .str());
124
125 // Create a preprocessor #include FixIt hint (createIncludeInsertion checks
126 // whether this already exists).
127 Diagnostic << IncludeInserter.createIncludeInsertion(
128 Source.getFileID(ComparisonExpr->getBeginLoc()),
129 AbseilStringsMatchHeader);
130 }
131
registerPPCallbacks(const SourceManager & SM,Preprocessor * PP,Preprocessor * ModuleExpanderPP)132 void StringFindStartswithCheck::registerPPCallbacks(
133 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
134 IncludeInserter.registerPreprocessor(PP);
135 }
136
storeOptions(ClangTidyOptions::OptionMap & Opts)137 void StringFindStartswithCheck::storeOptions(
138 ClangTidyOptions::OptionMap &Opts) {
139 Options.store(Opts, "StringLikeClasses",
140 utils::options::serializeStringList(StringLikeClasses));
141 Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle());
142 Options.store(Opts, "AbseilStringsMatchHeader", AbseilStringsMatchHeader);
143 }
144
145 } // namespace clang::tidy::abseil
146