[clang-tidy] Allows the prevailing include header guard in Flang ...

[schweitz]

Summary

to be recognized rather than flagged as a violation in phabricator.

[njames93]

Would you be able to add some unit tests for this in a follow up.
clang-tools-extra/unittests/clang-tidy/LLVMModuleTest.cpp is where they live.

clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp

std::string LLVMHeaderGuardCheck::getHeaderGuard(StringRef Filename,
   std::replace(Guard.begin(), Guard.end(), '/', '_');
   std::replace(Guard.begin(), Guard.end(), '.', '_');
   std::replace(Guard.begin(), Guard.end(), '-', '_');
 
   // The prevalent style in clang is LLVM_CLANG_FOO_BAR_H
   if (StringRef(Guard).startswith("clang"))
     Guard = "LLVM_" + Guard;
 
+  // The prevalent style in flang is FORTRAN_FOO_BAR_H
+  if (StringRef(Guard).startswith("flang"))
+    Guard = "FORTRAN" + Guard.substr(sizeof("flang") - 1);
+
   return StringRef(Guard).upper();
 }
 
 } // namespace llvm_check
 } // namespace tidy
 } // namespace clang