1 files changed, 90 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
new file mode 100644
index 00000000000..a278be14958
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/google/GlobalVariableDeclarationCheck.cpp
@@ -0,0 +1,90 @@
+//===--- GlobalVariableDeclarationCheck.cpp - clang-tidy-------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GlobalVariableDeclarationCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+
+#include <string>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace google {
+namespace objc {
+
+namespace {
+
+FixItHint generateFixItHint(const VarDecl *Decl, bool IsConst) {
+  char FC = Decl->getName()[0];
+  if (!llvm::isAlpha(FC) || Decl->getName().size() == 1) {
+    // No fix available if first character is not alphabetical character, or it
+    // is a single-character variable, since it is difficult to determine the 
+    // proper fix in this case. Users should create a proper variable name by
+    // their own.
+    return FixItHint();
+  }
+  char SC = Decl->getName()[1];
+  if ((FC == 'k' || FC == 'g') && !llvm::isAlpha(SC)) {
+    // No fix available if the prefix is correct but the second character is not
+    // alphabetical, since it is difficult to determine the proper fix in this
+    // case.
+    return FixItHint();
+  }
+  auto NewName = (IsConst ? "k" : "g") +
+                 llvm::StringRef(std::string(1, FC)).upper() +
+                 Decl->getName().substr(1).str();
+  return FixItHint::CreateReplacement(
+      CharSourceRange::getTokenRange(SourceRange(Decl->getLocation())),
+      llvm::StringRef(NewName));
+}
+}  // namespace
+
+void GlobalVariableDeclarationCheck::registerMatchers(MatchFinder *Finder) {
+  // The relevant Style Guide rule only applies to Objective-C.
+  if (!getLangOpts().ObjC1 && !getLangOpts().ObjC2) {
+    return;
+  }
+  // need to add two matchers since we need to bind different ids to distinguish
+  // constants and variables. Since bind() can only be called on node matchers,
+  // we cannot make it in one matcher.
+  Finder->addMatcher(
+      varDecl(hasGlobalStorage(), unless(hasType(isConstQualified())),
+              unless(matchesName("::g[A-Z]")))
+          .bind("global_var"),
+      this);
+  Finder->addMatcher(varDecl(hasGlobalStorage(), hasType(isConstQualified()),
+                             unless(matchesName("::k[A-Z]")))
+                         .bind("global_const"),
+                     this);
+}
+
+void GlobalVariableDeclarationCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_var")) {
+    diag(Decl->getLocation(),
+         "non-const global variable '%0' must have a name which starts with "
+         "'g[A-Z]'")
+        << Decl->getName() << generateFixItHint(Decl, false);
+  }
+  if (const auto *Decl = Result.Nodes.getNodeAs<VarDecl>("global_const")) {
+    diag(Decl->getLocation(),
+         "const global variable '%0' must have a name which starts with "
+         "'k[A-Z]'")
+        << Decl->getName() << generateFixItHint(Decl, true);
+  }
+}
+
+}  // namespace objc
+}  // namespace google
+}  // namespace tidy
+}  // namespace clang