git-debrebase: Recognise anchors by commit annotation, only

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

2 files changed, 11 insertions, 21 deletions

diff --git a/NOTES.git-debrebase b/NOTES.git-debrebase
index 476120f..ca78c93 100644
--- a/NOTES.git-debrebase
+++ b/NOTES.git-debrebase
@@ -1,5 +1,7 @@
 TODO
-   recognise anchor merge by annotation, not just by structure
+   --anchor option to specify commit(s) to treat as as anchor(s)
+
+   rename "launder" operation to "launder-v0"
 
    reference docs
       git-debrebase(5)   data model
diff --git a/git-debrebase b/git-debrebase
index 92fa86b..bc98756 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -412,7 +412,7 @@ sub classify ($) {
 
 	my $badanchor = sub { $unknown->("git-debrebase \`anchor' but @_"); };
 	@p == 2 or return $badanchor->("has other than two parents");
-	$haspatches and return $unknown->("contains debian/patches");
+	$haspatches and return $badanchor->("contains debian/patches");
 
 	# How to decide about l/r ordering of anchors ?  git
 	# --topo-order prefers to expand 2nd parent first.  There's
@@ -421,26 +421,14 @@ sub classify ($) {
 	# way also there's also an easy rune to look for the upstream
 	# patches (--topo-order).
 
-	# The above tells us which way *we* will generate them.  But we
-	# might encounter ad-hoc anchor merges generated manually,
-	# which might be the other way around.  In principle, in some odd
-	# situations, an anchor merge might have two identical parents.
-	# In that case we guess which way round it is (ie, which parent
-	# has the upstream history).  The order of the 2-iteration loop
-	# controls which guess we make.
-
-	# XXX we are going to desupport non-git-debrebase-generated anchors
-
-	foreach my $prevbrw (qw(0 1)) {
-	    if (!$p[$prevbrw]{IsOrigin} && # breakwater never starts with an origin
-		!($p[!$prevbrw]{Differs} & ~DS_DEB) && # no non-debian changess
-		!($p[$prevbrw]{Differs} & ~D_UPS)) { # no non-upstream changes
-		return $classify->(qw(Anchor),
-				   OrigParents => [ $p[!$prevbrw] ]);
-	    }
-	}
+	$p[0]{IsOrigin} and $badanchor->("is an origin commit");
+	$p[1]{Differs} & ~DS_DEB and
+	    $badanchor->("upstream files differ from left parent");
+	$p[0]{Differs} & ~D_UPS and
+	    $badanchor->("debian/ differs from right parent");
 
-	$badanchor->("violation");
+	return $classify->(qw(Anchor),
+			   OrigParents => [ $p[1] ]);
     }
 
     if (@p == 1) {