Modules: Document that ReadASTCore exits its final loop via `return`, NFC

The final loop never breaks.  Document that by following it with
llvm_unreachable.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@355294 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 9626418f6862c68aaf284da42fec31e381465a5a..5ad21604f4e7e341f2cbc6e00f515ba50bd07f21 100644 (file)
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -4257,7 +4257,7 @@ ASTReader::ReadASTCore(StringRef FileName,
     }
   }
 
-  return Success;
+  llvm_unreachable("unexpected break; expected return");
 }
 
 ASTReader::ASTReadResult