1 //===--- UseTransparentFunctorsCheck.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 "UseTransparentFunctorsCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang::tidy::modernize {
16
UseTransparentFunctorsCheck(StringRef Name,ClangTidyContext * Context)17 UseTransparentFunctorsCheck::UseTransparentFunctorsCheck(
18 StringRef Name, ClangTidyContext *Context)
19 : ClangTidyCheck(Name, Context), SafeMode(Options.get("SafeMode", false)) {}
20
storeOptions(ClangTidyOptions::OptionMap & Opts)21 void UseTransparentFunctorsCheck::storeOptions(
22 ClangTidyOptions::OptionMap &Opts) {
23 Options.store(Opts, "SafeMode", SafeMode);
24 }
25
registerMatchers(MatchFinder * Finder)26 void UseTransparentFunctorsCheck::registerMatchers(MatchFinder *Finder) {
27 const auto TransparentFunctors =
28 classTemplateSpecializationDecl(
29 unless(hasAnyTemplateArgument(refersToType(voidType()))),
30 hasAnyName("::std::plus", "::std::minus", "::std::multiplies",
31 "::std::divides", "::std::modulus", "::std::negate",
32 "::std::equal_to", "::std::not_equal_to", "::std::greater",
33 "::std::less", "::std::greater_equal", "::std::less_equal",
34 "::std::logical_and", "::std::logical_or",
35 "::std::logical_not", "::std::bit_and", "::std::bit_or",
36 "::std::bit_xor", "::std::bit_not"))
37 .bind("FunctorClass");
38
39 // Non-transparent functor mentioned as a template parameter. FIXIT.
40 Finder->addMatcher(
41 loc(qualType(
42 unless(elaboratedType()),
43 hasDeclaration(classTemplateSpecializationDecl(
44 unless(hasAnyTemplateArgument(templateArgument(refersToType(
45 qualType(pointsTo(qualType(isAnyCharacter()))))))),
46 hasAnyTemplateArgument(
47 templateArgument(refersToType(qualType(hasDeclaration(
48 TransparentFunctors))))
49 .bind("Functor"))))))
50 .bind("FunctorParentLoc"),
51 this);
52
53 if (SafeMode)
54 return;
55
56 // Non-transparent functor constructed. No FIXIT. There is no easy way
57 // to rule out the problematic char* vs string case.
58 Finder->addMatcher(cxxConstructExpr(hasDeclaration(cxxMethodDecl(
59 ofClass(TransparentFunctors))),
60 unless(isInTemplateInstantiation()))
61 .bind("FuncInst"),
62 this);
63 }
64
65 static const StringRef Message = "prefer transparent functors '%0<>'";
66
getInnerTypeLocAs(TypeLoc Loc)67 template <typename T> static T getInnerTypeLocAs(TypeLoc Loc) {
68 T Result;
69 while (Result.isNull() && !Loc.isNull()) {
70 Result = Loc.getAs<T>();
71 Loc = Loc.getNextTypeLoc();
72 }
73 return Result;
74 }
75
check(const MatchFinder::MatchResult & Result)76 void UseTransparentFunctorsCheck::check(
77 const MatchFinder::MatchResult &Result) {
78 const auto *FuncClass =
79 Result.Nodes.getNodeAs<ClassTemplateSpecializationDecl>("FunctorClass");
80 if (const auto *FuncInst =
81 Result.Nodes.getNodeAs<CXXConstructExpr>("FuncInst")) {
82 diag(FuncInst->getBeginLoc(), Message) << FuncClass->getName();
83 return;
84 }
85
86 const auto *Functor = Result.Nodes.getNodeAs<TemplateArgument>("Functor");
87 const auto FunctorParentLoc =
88 Result.Nodes.getNodeAs<TypeLoc>("FunctorParentLoc")
89 ->getAs<TemplateSpecializationTypeLoc>();
90
91 if (!FunctorParentLoc)
92 return;
93
94 unsigned ArgNum = 0;
95 const auto *FunctorParentType =
96 FunctorParentLoc.getType()->castAs<TemplateSpecializationType>();
97 for (; ArgNum < FunctorParentType->template_arguments().size(); ++ArgNum) {
98 const TemplateArgument &Arg =
99 FunctorParentType->template_arguments()[ArgNum];
100 if (Arg.getKind() != TemplateArgument::Type)
101 continue;
102 QualType ParentArgType = Arg.getAsType();
103 if (ParentArgType->isRecordType() &&
104 ParentArgType->getAsCXXRecordDecl() ==
105 Functor->getAsType()->getAsCXXRecordDecl())
106 break;
107 }
108 // Functor is a default template argument.
109 if (ArgNum == FunctorParentType->template_arguments().size())
110 return;
111 TemplateArgumentLoc FunctorLoc = FunctorParentLoc.getArgLoc(ArgNum);
112 auto FunctorTypeLoc = getInnerTypeLocAs<TemplateSpecializationTypeLoc>(
113 FunctorLoc.getTypeSourceInfo()->getTypeLoc());
114 if (FunctorTypeLoc.isNull())
115 return;
116
117 SourceLocation ReportLoc = FunctorLoc.getLocation();
118 if (ReportLoc.isInvalid())
119 return;
120 diag(ReportLoc, Message) << FuncClass->getName()
121 << FixItHint::CreateRemoval(
122 FunctorTypeLoc.getArgLoc(0).getSourceRange());
123 }
124
125 } // namespace clang::tidy::modernize
126