#14808: GHC HEAD regression: GADT constructors no longer quantify tyvars in topological order -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: highest | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.5 checker) | Resolution: | Keywords: GADTs Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #14529, #14796 | Differential Rev(s): Phab:D4413 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"043466b9aac403553e2aaf8054c064016f963f80/ghc" 043466b9/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="043466b9aac403553e2aaf8054c064016f963f80" Rename the types in a GADT constructor in toposorted order Previously, we were extracting the free variables from a GADT constructor in an incorrect order, which caused the type variables for the constructor's type signature to end up in non-toposorted order. Thankfully, rearranging the order of types during renaming makes swift work of this bug. This fixes a regression introduced in commit fa29df02a1b0b926afb2525a258172dcbf0ea460. For whatever reason, that commit also commented out a significant portion of the `T13123` test. This code appears to work, so I've opted to uncomment it. Test Plan: make test TEST=T14808 Reviewers: simonpj, bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie, carter GHC Trac Issues: #14808 Differential Revision: https://phabricator.haskell.org/D4413 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14808#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler