From ae6a56ee467d675776be75dc982f5efb2135d3d4 Mon Sep 17 00:00:00 2001 From: Ben Gamari Date: Tue, 29 Mar 2016 16:30:29 +0200 Subject: users-guide/rel-notes: Note broken-ness of ImpredicativeTypes --- docs/users_guide/8.0.1-notes.rst | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'docs') diff --git a/docs/users_guide/8.0.1-notes.rst b/docs/users_guide/8.0.1-notes.rst index 2ebba6e1e6..fe77bf42c0 100644 --- a/docs/users_guide/8.0.1-notes.rst +++ b/docs/users_guide/8.0.1-notes.rst @@ -205,6 +205,14 @@ Language result, :ghc-flag:`-XDeriveTraversable` now works on datatypes that contain arguments which have unlifted types. +- Note that the :ghc-flag:`-XImpredicativeTypes` extension, which has been + :ghc-wiki:`known ` to be broken for many years, is even more + broken than usual in this release (see :ghc-ticket:`11319`, + :ghc-ticket:`11675`, and others). During pre-release testing we encountered + a number of projects that broke with confusing type errors due to (often + unnecessary) use of :ghc-flag:`-XImpredicativeTypes`. Users of + :ghc-flag:`-XImpredicativeTypes` do so at their own risk! + Compiler ~~~~~~~~ -- cgit v1.2.1