Re: Spurious recompilations when using a compiler plugin

is it possible that this is also connected to https://ghc.haskell.org/trac/ghc/ticket/13604 ? On Tue, Sep 19, 2017 at 10:00 AM Ben Gamari wrote:

Conal Elliott writes:

...

It appears that use of GHC plugins causes client code to get needlessly recompiled. (See Trac issues 12567 https://ghc.haskell.org/trac/ghc/ticket/12567 and 7414 https://ghc.haskell.org/trac/ghc/ticket/7414.) It’s becoming more of a problem for usability of the plugin http://conal.net/papers/compiling-to-categories I’ve been developing, and I’m wondering what can be done. Some questions:

- Is there any work in progress on fixing this situation? - Are there serious obstacles to fixing it? - Do plugin writers or users have any workarounds?

I think the real question is what sort of interface do plugin authors need?

I suspect there are a few distinct tasks here,

* compute and record module implementation hashes in interface files

* to include plugin implementation hashes in the recompilation check

* to provide an interface allowing a plugin to compute a hash of its arguments which can be included into the recompilation check. One way of realising this would be to add a field like the following to Plugin,

pluginHash :: [CommandLineOption] -> Maybe Fingerprint -- Nothing would denote "always rebuild"

Would this help in your case?

This would allow us to fix the TH problem in #7277 and fix the plugins problem in #7414 and #12567 in a nearly optimal way (assuming the plugin author is able to precisely define a hash).

None of this is terribly difficult and given Nick's recent work on his row types plugin, it seems like it's getting more urgent.

Cheers,

- Ben _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs