More tests for detail messages, plus a new one.

The array-length instruction is likely to encounter nulls.

Change-Id: I628f5f00dfaff9414740e2f7015b9fb3d34a1bc9
diff --git a/src/compiler.cc b/src/compiler.cc
index 4d98d61..aa465c3 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -245,9 +245,7 @@
   }
 
   // Capitalize the instruction set, because that's what we do in the build system.
-  std::ostringstream instruction_set_name_os;
-  instruction_set_name_os << instruction_set;
-  std::string instruction_set_name(instruction_set_name_os.str());
+  std::string instruction_set_name(ToStr<InstructionSet>(instruction_set).str());
   for (size_t i = 0; i < instruction_set_name.size(); ++i) {
     instruction_set_name[i] = toupper(instruction_set_name[i]);
   }