Fix GCC's -Wreturn-type warning

Author: Igor S. Gerasimov

lldb/source/DataFormatters/TypeSummary.cpp

@@ -58,6 +58,8 @@ std::string TypeSummaryImpl::GetSummaryKindName() {
     return "c++";
   case Kind::eBytecode:
     return "bytecode";
+  default:
+    llvm_unreachable("Unknown type kind name");
   }
 }
 

lldb/source/ValueObject/DILLexer.cpp

@@ -29,6 +29,8 @@ llvm::StringRef Token::GetTokenName(Kind kind) {
     return "l_paren";
   case Kind::r_paren:
     return "r_paren";
+  default:
+    llvm_unreachable("Unknown token name");
   }
 }