Interactively finding a method’s file with which generally works well, except for Core. Finding where a type or a function is defined however is more indirect by going through the module, and the module definition’s file often isn’t the file with the type or function. A file isn’t printed for Base or Core either.
The motivating context is Core.Array being reimplemented in Julia, I’m curious to see what’s going on there. The Github issue is enough, but I’m wondering if there’s something as quick and easy as which for this.