Heheh yes tobyink I thought about that too, but the OP appears to want to forbid in code the use of a string as a hash key, whether quoted or not, and only allow using a declared variable. IIUC.

No, he wants to avoid stringification of hash keys, especially of barewords.

"What I really want is a way to make $hash{bare_word} a compile-time error in a lexical scope..."



The way forward always starts with a minimal test.