better output & docs for when DEB_* isn't enough

2 files changed, 22 insertions, 13 deletions

diff --git a/dh-elpa.el b/dh-elpa.el
index d7a9766..094913e 100644
--- a/dh-elpa.el
+++ b/dh-elpa.el
@@ -114,18 +114,24 @@ Versions taken from environment variables are run through
 `dhelpa-sanitise-version'."
   ;; If one of these environment variables is the empty string, it's
   ;; as good as unset, so we replace that with the nil value.
-  (let ((upstream-version (null-empty-string
-                           (dhelpa-sanitise-version
-                            (getenv "DEB_UPSTREAM_VERSION"))))
-        (version-upstream (null-empty-string
-                           (dhelpa-sanitise-version
-                            (getenv "DEB_VERSION_UPSTREAM")))))
+  (let* ((upstream-version (null-empty-string
+                            (getenv "DEB_UPSTREAM_VERSION")))
+         (version-upstream (null-empty-string
+                            (getenv "DEB_VERSION_UPSTREAM")))
+         (version (if upstream-version upstream-version version-upstream))
+         (sanitised-version (dhelpa-sanitise-version version)))
+    ;; sanity check #1
     (if (and upstream-version
              version-upstream
              (not (string= upstream-version version-upstream)))
         (error "The DEB_UPSTREAM_VERSION and DEB_VERSION_UPSTREAM
 environment variables are both set, but they disagree.")
-      (if upstream-version upstream-version version-upstream))))
+      ;; sanity check #2
+      (unless (ignore-errors (version-to-list sanitised-version))
+        (error (concat "E: The Debian version " version " cannot be used as an ELPA version.
+See dh_elpa(1) HINTS for how to deal with this.")))
+      ;; if we got this far, return it
+      sanitised-version)))
 
 ;;;###autoload
 (defun dhelpa-sanitise-version (version)
diff --git a/dh_elpa.in b/dh_elpa.in
index d260e48..ca5f6a2 100755
--- a/dh_elpa.in
+++ b/dh_elpa.in
@@ -326,9 +326,10 @@ substvars
 
 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:
+headers or *-pkg.el file), 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
 
@@ -337,6 +338,8 @@ these is just to prepend the following to your rules file:
 
 =back
 
-Note that this will fail in certain cases where the Debian upstream
-version cannot be translated into an adequate Emacs version string.
-See the documentation for the `dhelpa-sanitise-version' function.
+Certain Debian upstream version strings cannot be translated into
+version strings Emacs will accept (see the docstring for the Emacs
+function `version-to-list' for details).  dh_elpa will error out if
+the version cannot be translated.  You should resort to patching in a
+Package-Version header or adding a *-pkg.el file.