Fix MSVC "not all control paths return a value" warning. NFC.

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index fa2f07a..c368a61 100644 (file)
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3390,6 +3390,7 @@ private:
       // A template passed as argument can be not in ParentDC.
       return false;
     }
+    llvm_unreachable("Unknown TemplateArgument::ArgKind enum");
   };
 };
 } // namespace