add support for constants with appropriate prefix. Start with 'k' is not the only option. This is according to http://google.github.io/styleguide/objcguide.html#constants

[Wizard]

Summary

Supporting static constant name with appropriate prefix like ABCMyConstantVariable.

[Wizard]

fix format

[stephanemoore]

I have this change out for review as well:
https://reviews.llvm.org/D43581

[Wizard]

In D43640#1016287, @stephanemoore wrote:

I have this change out for review as well:
https://reviews.llvm.org/D43581

Ah cool. Your change looks good. Technically the same as mine. I will discard this diff.

clang-tidy/google/GlobalVariableDeclarationCheck.cpp

 
 namespace clang {
 namespace tidy {
 namespace google {
 namespace objc {
 
 namespace {
 
-AST_MATCHER(VarDecl, isLocalVariable) {
-  return Node.isLocalVarDecl();
+AST_MATCHER(VarDecl, isLocalVariable) { 
+  return Node.isLocalVarDecl(); 
 }
 
 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 
+    // 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
void GlobalVariableDeclarationCheck::registerMatchers(MatchFinder *Finder) {
   // isLocalVariable().
   Finder->addMatcher(
       varDecl(hasGlobalStorage(), unless(hasType(isConstQualified())),
               unless(isLocalVariable()), unless(matchesName("::g[A-Z]")))
           .bind("global_var"),
       this);
   Finder->addMatcher(varDecl(hasGlobalStorage(), hasType(isConstQualified()),
                              unless(isLocalVariable()),
-                             unless(matchesName("::k[A-Z]")))
+                             unless(matchesName("::(k|[A-Z]{2,})[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]'")
+         "const global variable '%0' must have an appropriate prefix or a name "
+         "which starts with 'k[A-Z]'")
         << Decl->getName() << generateFixItHint(Decl, true);
   }
 }
 
 }  // namespace objc
 }  // namespace google
 }  // namespace tidy
 }  // namespace clang

test/clang-tidy/google-objc-global-variable-declaration.m

 // RUN: %check_clang_tidy %s google-objc-global-variable-declaration %t
 
 @class NSString;
 static NSString* const myConstString = @"hello";
-// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable 'myConstString' must have a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable 'myConstString' must have an appropriate prefix or a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* const kMyConstString = @"hello";
 
 static NSString* MyString = @"hi";
 // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: non-const global variable 'MyString' must have a name which starts with 'g[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* gMyString = @"hi";
 
 NSString* globalString = @"test";
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: non-const global variable 'globalString' must have a name which starts with 'g[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: NSString* gGlobalString = @"test";
 
 static NSString* a = @"too simple";
 // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: non-const global variable 'a' must have a name which starts with 'g[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* a = @"too simple";
 
 static NSString* noDef;
 // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: non-const global variable 'noDef' must have a name which starts with 'g[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* gNoDef;
 
 static NSString* const _notAlpha = @"NotBeginWithAlpha";
-// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable '_notAlpha' must have a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable '_notAlpha' must have an appropriate prefix or a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* const _notAlpha = @"NotBeginWithAlpha";
 
 static NSString* const k_Alpha = @"SecondNotAlpha";
-// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable 'k_Alpha' must have a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
+// CHECK-MESSAGES: :[[@LINE-1]]:24: warning: const global variable 'k_Alpha' must have an appropriate prefix or a name which starts with 'k[A-Z]' [google-objc-global-variable-declaration]
 // CHECK-FIXES: static NSString* const k_Alpha = @"SecondNotAlpha";
 
 static NSString* const kGood = @"hello";
+static NSString* const ABCGood = @"I have a prefix";
 static NSString* gMyIntGood = 0;
 
 @implementation Foo
 - (void)f {
     int x = 0;
     static int bar;
     static const int baz = 42;
 }
 @end