1 //===--- GlobalVariableDeclarationCheck.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 "GlobalVariableDeclarationCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "llvm/ADT/StringExtras.h"
13 #include "llvm/ADT/StringRef.h"
14
15 #include <string>
16
17 using namespace clang::ast_matchers;
18
19 namespace clang {
20 namespace tidy {
21 namespace google {
22 namespace objc {
23
24 namespace {
25
AST_MATCHER(VarDecl,isLocalVariable)26 AST_MATCHER(VarDecl, isLocalVariable) { return Node.isLocalVarDecl(); }
27
generateFixItHint(const VarDecl * Decl,bool IsConst)28 FixItHint generateFixItHint(const VarDecl *Decl, bool IsConst) {
29 if (IsConst && (Decl->getStorageClass() != SC_Static)) {
30 // No fix available if it is not a static constant, since it is difficult
31 // to determine the proper fix in this case.
32 return FixItHint();
33 }
34
35 char FC = Decl->getName()[0];
36 if (!llvm::isAlpha(FC) || Decl->getName().size() == 1) {
37 // No fix available if first character is not alphabetical character, or it
38 // is a single-character variable, since it is difficult to determine the
39 // proper fix in this case. Users should create a proper variable name by
40 // their own.
41 return FixItHint();
42 }
43 char SC = Decl->getName()[1];
44 if ((FC == 'k' || FC == 'g') && !llvm::isAlpha(SC)) {
45 // No fix available if the prefix is correct but the second character is
46 // not alphabetical, since it is difficult to determine the proper fix in
47 // this case.
48 return FixItHint();
49 }
50
51 auto NewName = (IsConst ? "k" : "g") +
52 llvm::StringRef(std::string(1, FC)).upper() +
53 Decl->getName().substr(1).str();
54
55 return FixItHint::CreateReplacement(
56 CharSourceRange::getTokenRange(SourceRange(Decl->getLocation())),
57 llvm::StringRef(NewName));
58 }
59 } // namespace
60
registerMatchers(MatchFinder * Finder)61 void GlobalVariableDeclarationCheck::registerMatchers(MatchFinder *Finder) {
62 // The relevant Style Guide rule only applies to Objective-C.
63 if (!getLangOpts().ObjC)
64 return;
65
66 // need to add two matchers since we need to bind different ids to distinguish
67 // constants and variables. Since bind() can only be called on node matchers,
68 // we cannot make it in one matcher.
69 //
70 // Note that hasGlobalStorage() matches static variables declared locally
71 // inside a function or method, so we need to exclude those with
72 // isLocalVariable().
73 Finder->addMatcher(
74 varDecl(hasGlobalStorage(), unless(hasType(isConstQualified())),
75 unless(isLocalVariable()), unless(matchesName("::g[A-Z]")))
76 .bind("global_var"),
77 this);
78 Finder->addMatcher(varDecl(hasGlobalStorage(), hasType(isConstQualified()),
79 unless(isLocalVariable()),
80 unless(matchesName("::(k[A-Z])|([A-Z][A-Z0-9])")))
81 .bind("global_const"),
82 this);
83 }
84
check(const MatchFinder::MatchResult & Result)85 void GlobalVariableDeclarationCheck::check(
86 const MatchFinder::MatchResult &Result) {
87 if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_var")) {
88 if (Decl->isStaticDataMember())
89 return;
90 diag(Decl->getLocation(),
91 "non-const global variable '%0' must have a name which starts with "
92 "'g[A-Z]'")
93 << Decl->getName() << generateFixItHint(Decl, false);
94 }
95 if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_const")) {
96 if (Decl->isStaticDataMember())
97 return;
98 diag(Decl->getLocation(),
99 "const global variable '%0' must have a name which starts with "
100 "an appropriate prefix")
101 << Decl->getName() << generateFixItHint(Decl, true);
102 }
103 }
104
105 } // namespace objc
106 } // namespace google
107 } // namespace tidy
108 } // namespace clang
109