clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp

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