document DEB_* functionality in dh_elpa(1)

2 files changed, 18 insertions, 0 deletions

diff --git a/debian/changelog b/debian/changelog
index d2ac39e..7814f7e 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -18,6 +18,7 @@ dh-elpa (1.0) UNRELEASED; urgency=medium
   [ Rémi Vanicat & Sean Whitton ]
   * use DEB_UPSTREAM_VERSION or DEB_VERSION_UPSTREAM as elpa version if
     there is no version line in the main "*.el" file
+  * add HINTS section to dh_elpa(1) documenting this
 
  -- Rémi Vanicat <vanicat@debian.org>  Mon, 11 Jul 2016 15:29:38 +0200
 
diff --git a/dh_elpa.in b/dh_elpa.in
index 94fa94f..67cd9d8 100755
--- a/dh_elpa.in
+++ b/dh_elpa.in
@@ -320,3 +320,20 @@ substvars
 
 =back
 
+=head1 HINTS
+
+=head2 Specifying the package version
+
+If dh_elpa can't determine the package version by looking at *.el
+files (usually because upstream has failed to include the proper
+headers), it will fallback to the DEB_UPSTREAM_VERSION and
+DEB_VERSION_UPSTREAM environment variables.  An easy way to set one of
+these is just to prepend the following to your rules file:
+
+=over 4
+
+    include /usr/share/dpkg/pkg-info.mk
+    export DEB_VERSION_UPSTREAM
+
+=back
+