[commit: ghc] ghc-7.2: Add a release note about TypeSynonymInstances change of behaviour (cdea1a8)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : ghc-7.2

http://hackage.haskell.org/trac/ghc/changeset/cdea1a8eb6e09a0bd5f365f8f23987e92f7a1297

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

commit cdea1a8eb6e09a0bd5f365f8f23987e92f7a1297
Author: Ian Lynagh <igloo at earth.li>
Date:   Fri Aug 5 20:28:49 2011 +0100

    Add a release note about TypeSynonymInstances change of behaviour
    
    As discussed in #5377

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 docs/users_guide/7.2.1-notes.xml |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/docs/users_guide/7.2.1-notes.xml b/docs/users_guide/7.2.1-notes.xml
index 58ded15..91bb503 100644
--- a/docs/users_guide/7.2.1-notes.xml
+++ b/docs/users_guide/7.2.1-notes.xml
@@ -50,6 +50,27 @@
 
       <listitem>
         <para>
+          The <literal>TypeSynonymInstances</literal> extension now
+          correctly requires that instances are valid once the type
+          synonym is expanded. For example, in order to have
+        </para>
+<programlisting>
+instance SomeClass String where
+    ...
+</programlisting>
+        <para>
+          you need both <literal>TypeSynonymInstances</literal> and
+          <literal>FlexibleInstances</literal> enabled, as the latter
+          is necessary for
+        </para>
+<programlisting>
+instance SomeClass [Char] where
+    ...
+</programlisting>
+      </listitem>
+
+      <listitem>
+        <para>
           The <literal>DatatypeContexts</literal> extension (which will
           not be in the next Haskell language standard) is now off by
           default, and deprecated. It is still enabled by the