Clarify handling of architecture restrictions in dependencies

Add an explanation of the example and an additional example and
explanation for handling of architecture restrictions within alternatives.
Thanks, Guillem Jover.  (Closes: #163666)

diff --git a/policy.sgml b/policy.sgml
index 7de382d39ff9ba4dd367575ecbb95db7f64518ad..120fc3aefbb152b8778b7fdce910e7bd777b4b0b 100644 (file)
--- a/policy.sgml
+++ b/policy.sgml
@@ -4188,6 +4188,22 @@ Build-Depends-Indep: texinfo
 Build-Depends: kernel-headers-2.2.10 [!hurd-i386],
   hurd-dev [hurd-i386], gnumach-dev [hurd-i386]
          </example>
+         requires <tt>kernel-headers-2.2.0</tt> on all architectures
+         other than hurd-i386 and requires <tt>hurd-dev</tt> and
+         <tt>gnumach-dev</tt> only on hurd-i386.
+       </p>
+
+       <p>
+         If the architecture-restricted dependency is part of a set of
+         alternatives using <tt>|</tt>, that branch of the alternative is
+         ignored completely on architectures that do not match the
+         restriction.  For example:
+         <example compact="compact">
+Build-Depends: foo [!i386] | bar [!amd64]
+         </example>
+         is equivalent to <tt>bar</tt> on the i386 architecture, to
+         <tt>foo</tt> on the amd64 architecture, and to <tt>foo |
+         bar</tt> on all other architectures.
        </p>
 
        <p>