#9173: Better type error messages -------------------------------------+------------------------------------- Reporter: simonpj | Owner: goldfire Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: | TypeErrorMessages Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by nineonine): Update: I was able to locate all the places where we make `TypeEqOrigin`. We do this with a help of a smart constructor `mkCheckExpType`. There are around 80-90 places (across 12 modules) where we use it. There is another function `synKnownType` that uses `mkCheckExpType` which has another 25 occurrences. For now I just used dummy text everywhere to be able to compile it. Here you can see more detailed search results for these functions: * `mkCheckExpType` - https://lpaste.net/7745839270543228928 * `synKnownType` - https://lpaste.net/4510196100136697856 I have already changed some of the messages where I was able to infer the context and come up with meaningful explanations. Here is a screenshot of examples from the ticket with new messages - https://prnt.sc/kycm4c, however, some places are tricky so I will probably need more time to spend on them. Right now my plan is the following - I want to come up with all the test cases(programs) that would call all the code parts where we use the above mentioned functions. By doing that, I will slowly weed out all the dummy messages and replace with meaningful ones. As suggested, I am collecting all the notes of my changes. Perhaps, it is a good time to submit a patch to Phabricator? We could proceed with a discussion there and it would be much easier to discuss all the new messages (with line comments). By the way, If someone could code review and help with new messages - that would be greatly appreciated! Thank you. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9173#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler