[commit: ghc] wip/rae: Clarify parsing infelicity. (c306218)

[git at git.haskell.org]

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

On branch  : wip/rae
Link       : http://ghc.haskell.org/trac/ghc/changeset/c3062184fbe46b7b9ad781c184276f984fa45c93/ghc

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

commit c3062184fbe46b7b9ad781c184276f984fa45c93
Author: Richard Eisenberg <eir at cis.upenn.edu>
Date:   Sat Sep 19 16:44:29 2015 -0400

    Clarify parsing infelicity.
    
    This fixes #10855.


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

c3062184fbe46b7b9ad781c184276f984fa45c93
 docs/users_guide/bugs.xml | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/docs/users_guide/bugs.xml b/docs/users_guide/bugs.xml
index 1b4d5c9..bff2bcf 100644
--- a/docs/users_guide/bugs.xml
+++ b/docs/users_guide/bugs.xml
@@ -101,6 +101,18 @@ main = do args <- getArgs
 <programlisting>
     (let x = 42 in x == 42 == True)</programlisting></para>
 	</listitem>
+
+	<listitem>
+	  <para>The Haskell Report allows you to put a unary
+	  <literal>-</literal> preceding certain expressions headed by
+	  keywords, allowing constructs like <literal>- case x of
+	  ...</literal> or <literal>- do { ... }</literal>. GHC does
+	  not allow this. Instead, unary <literal>-</literal> is
+	  allowed before only expressions that could potentially
+	  be applied as a function.
+	  </para>
+	</listitem>
+
       </itemizedlist>
     </sect3>