Mentoring for implementing #8004

Simon Peyton-Jones simonpj at
Thu Aug 1 08:48:49 CEST 2013

Rather than scatter these AMP checks here and there, I'd suggest adding
	checkAMPStuff tcg_env
on line 206 or so of TcRnDriver, near the call to reportUnusedNames.

This happens after typechecking is complete.  The tcg_env includes all the newly-defined instances (in tcg_insts), what is in scope etc (tcg_rdr_env), so all the stuff you need is to hand.  You can write checkAMPStuff in one place.


|  -----Original Message-----
|  From: ghc-devs [mailto:ghc-devs-bounces at] On Behalf Of David
|  Luposchainsky
|  Sent: 31 July 2013 13:57
|  To: ghc-devs at
|  Subject: Mentoring for implementing #8004
|  Hey Devs,
|  I haven't worked on GHC before, so I'm having trouble finding an entry
|  point to implementing the AMP warnings (#8004). I only have a rough
|  working knowledge of GHC's inner workings, but it would be a shame if
|  the ticket wasn't resolved until the 7.8 deadline (which is somewhere in
|  September if I remember it right).
|  My last approach was grepping through the source for "DEPRECATED" and
|  seeing whether there would be an appropriate place for these warnings
|  there, but that wasn't very fruitful.
|  Long story short: can anyone point me in the right direction? I assume
|  the right place to look is somewhere in the typechecker where there's a
|  type class environment, and that's as far as I've come. (It's hard to
|  understand thousands of lines when you're not even sure you're in the
|  right place ...)
|  Greetings,
|  David
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|  ghc-devs at

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