#5211: Missing warning about redundant import for a class instance ---------------------------------+----------------------------------------- Reporter: Lemming | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 6.12.3 Resolution: fixed | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Type of failure: None/Unknown | Test Case: rename/should_fail/T5211 Blocked By: | Blocking: ---------------------------------+----------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"6353efc7694ba8ec86c091918e02595662169ae2/ghc" 6353efc7/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="6353efc7694ba8ec86c091918e02595662169ae2" Fix unused-import warnings This patch fixes a fairly long-standing bug (dating back to 2015) in RdrName.bestImport, namely commit 9376249b6b78610db055a10d05f6592d6bbbea2f Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Wed Oct 28 17:16:55 2015 +0000 Fix unused-import stuff in a better way In that patch got the sense of the comparison back to front, and thereby failed to implement the unused-import rules described in Note [Choosing the best import declaration] in RdrName This led to Trac #13064 and #15393 Fixing this bug revealed a bunch of unused imports in libraries; the ones in the GHC repo are part of this commit. The two important changes are * Fix the bug in bestImport * Modified the rules by adding (a) in Note [Choosing the best import declaration] in RdrName Reason: the previosu rules made Trac #5211 go bad again. And the new rule (a) makes sense to me. In unravalling this I also ended up doing a few other things * Refactor RnNames.ImportDeclUsage to use a [GlobalRdrElt] for the things that are used, rather than [AvailInfo]. This is simpler and more direct. * Rename greParentName to greParent_maybe, to follow GHC naming conventions * Delete dead code RdrName.greUsedRdrName Bumps a few submodules. Reviewers: hvr, goldfire, bgamari, simonmar, jrtc27 Subscribers: rwbarton, carter Differential Revision: https://phabricator.haskell.org/D5312 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5211#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler