Fix Trac #2518: add hs-boot files as an infelicty

diff --git a/docs/users_guide/bugs.xml b/docs/users_guide/bugs.xml
index fdeeaa8..4d79d24 100644 (file)
--- a/docs/users_guide/bugs.xml
+++ b/docs/users_guide/bugs.xml
@@ -105,7 +105,21 @@ main = do args <- getArgs
       <sect3 id="infelicities-Modules">
        <title>Module system and interface files</title>
        
-       <para>None known.</para>
+       <para>GHC requires the use of <literal>hs-boot</literal>
+         files to cut the recursive loops among mutually recursive modules
+         as described in <xref linkend="mutual-recursion"/>.  This more of an infelicity
+           than a bug: the Haskell Report says 
+         (<ulink url="http://haskell.org/onlinereport/modules.html#sect5.7">Section 5.7</ulink>) "Depending on the Haskell
+       implementation used, separate compilation of mutually
+       recursive modules may require that imported modules contain
+       additional information so that they may be referenced before
+       they are compiled. Explicit type signatures for all exported
+       values may be necessary to deal with mutual recursion. The
+       precise details of separate compilation are not defined by
+       this Report."
+
+       </para>
+
     </sect3>
 
     <sect3 id="infelicities-numbers">