[virtualwhys]

> I wager there is type inference going on

What will the compiler infer other than a value of type string?

> to supply something that would not one way or the other convert to the types that source can consume.

Well, clearly `source` takes a string, so it will happily accept "produckname" and blow up at run time.

Short of macros I know of no other compile time mechanism that would enable "safe" strings. The usual workaround is to not use plain string values at all and wrap in a sealed type.