[project @ 2004-06-23 10:31:02 by ross]

[ghc-hetmet.git] / ghc / docs / users_guide / ffi-chap.sgml

diff --git a/ghc/docs/users_guide/ffi-chap.sgml b/ghc/docs/users_guide/ffi-chap.sgml
index 0aaeabd..d622179 100644 (file)
--- a/ghc/docs/users_guide/ffi-chap.sgml
+++ b/ghc/docs/users_guide/ffi-chap.sgml
@@ -101,7 +101,7 @@ extern HsInt foo(HsInt a0);</programlisting>
       invoke <literal>foo()</literal> from C, just <literal>#include
       "Foo_stub.h"</literal> and call <literal>foo()</literal>.</para>
 
-      <sect3> 
+      <sect3 id="using-own-main"> 
        <title>Using your own <literal>main()</literal></title>
 
        <para>Normally, GHC's runtime system provides a
@@ -290,6 +290,26 @@ to be inlined across modules, use the command-line and package-configuration
 <option>-&num;include</option> mechanism.
 </para>
 
+      <sect3 id="finding-header-files">
+       <title>Finding Header files</title>
+
+       <para>Header files named by the <option>-&num;include</option>
+       option or in a <literal>foreign import</literal> declaration
+       are searched for using the C compiler's usual search path.
+       You can add directories to this search path using the
+       <option>-I</option> option (see <xref
+       linkend="c-pre-processor">).</para>
+
+       <para>Note: header files are ignored unless compiling via C.
+       If you had been compiling your code using the native code
+       generator (the default) and suddenly switch to compiling via
+       C, then you can get unexpected errors about missing include
+       files.  Compiling via C is enabled automatically when certain
+       options are given (eg. <option>-O</option> and
+       <option>-prof</option> both enable
+       <option>-fvia-C</option>).</para>
+      </sect3>
+
     </sect2>
 
     <sect2>