[commit: ghc] master: user-guide: Note Cabal version limitation (b90cac6)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/b90cac69b2abec7df998d1d447b3fe075eb8f15c/ghc

>---------------------------------------------------------------

commit b90cac69b2abec7df998d1d447b3fe075eb8f15c
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Thu Jan 14 15:46:31 2016 +0100

    user-guide: Note Cabal version limitation


>---------------------------------------------------------------

b90cac69b2abec7df998d1d447b3fe075eb8f15c
 docs/users_guide/8.0.1-notes.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/docs/users_guide/8.0.1-notes.rst b/docs/users_guide/8.0.1-notes.rst
index a5cc2b7..77f038d 100644
--- a/docs/users_guide/8.0.1-notes.rst
+++ b/docs/users_guide/8.0.1-notes.rst
@@ -7,6 +7,18 @@ The significant changes to the various parts of the compiler are listed
 in the following sections. There have also been numerous bug fixes and
 performance improvements over the 7.10 branch.
 
+.. warning::
+
+    Only Cabal versions 0.24 and newer will function properly with this release.
+    Consequently it will likely be necessary to recompile ``cabal-install``
+    before installing new packages.
+
+    The reason for this is a change in how packages are identified in GHC
+    8.0. While previous versions of Cabal identified packages to GHC with a
+    package key (with GHC's :ghc-flag:`-this-package-key` argument), GHC 8.0 and
+    later uses installed package IDs in place of package keys.
+
+
 Highlights
 ----------