Better "module defined multiple times" error

[hdgarrood]

from IRC - for the "module X has been defined multiple times" error, it would be nice to show every filename that defines a module X. Currently, if you get that error, you have to use grep or something and find it yourself, which is not catastrophic but also not the nicest user experience.

[mjgpy3]

I notice there's also a RedefinedIdent error type as well. Is showing files for that error also a desirable enhancement? If so, should it be done as part of this issue or a separate one?

[hdgarrood]

RedefinedIdent is only thrown during type checking, whereas RedefinedModule is thrown during desugaring. Type errors do seem to have good information about where they arose from, so I don't think RedefinedIdent suffers from the same issue that this issue is about. Having said that, I was unable to work out how to write a program that actually failed with that type error. Either way I don't think it's the same issue.

[hdgarrood]

Do you think it would make sense to store a module's filename inside the AST? That is, adding an extra argument to the Module constructor?