re PR ada/29157 (gnattools fail on cross compilation - Makefile bug?)

    gcc/
	PR ada/29157
	* doc/install.texi: Explain how to check for a clean environment when
	building GNAT.

From-SVN: r130675

gcc/ChangeLog

+2007-12-07  Samuel Tardieu  <sam@rfc1149.net>
+
+	PR ada/29157
+	* doc/install.texi: Explain how to check for a clean environment when
+	building GNAT.
+
 2007-12-07  Richard Guenther  <rguenther@suse.de>
 
 	* tree-profile.c (gcov_type_tmp_var): New global variable.

gcc/doc/install.texi

@@ -1913,6 +1913,12 @@ and has a sufficiently recent version; if too old a GNAT version is
 installed, the build will fail unless @option{--enable-languages} is
 used to disable building the Ada front end.
 
+@env{ADA_INCLUDE_PATH} and @env{ADA_OBJECT_PATH} environment variables
+must not be set when building the Ada compiler, the Ada tools, or the
+Ada runtime libraries. You can check that your build environment is clean
+by verifying that @samp{gnatls -v} lists only one explicit path in each
+section.
+
 @section Building with profile feedback
 
 It is possible to use profile feedback to optimize the compiler itself.  This