X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=dgit.git;a=blobdiff_plain;f=git-debrebase;h=830cfd5ea978586b68a6e995936bcf68e9dac7f7;hp=499cda2eef4946b72cfec4bbabc753c2aecb0ce7;hb=27b7f56727ea182349a38136977553fc5a256394;hpb=a264b74abe1251ab73163cfb9b5a04ff3d41eaf9

diff --git a/git-debrebase b/git-debrebase
index 499cda2e..830cfd5e 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -362,8 +362,8 @@ sub gbp_pq_export ($$$) {
 #  our own patch identification algorithm?
 #  this is an alternative strategy
 
-sub merge_series ($$;@) {
-    my ($newbase, $base_q, @input_qs) = @_;
+sub merge_series ($$$;@) {
+    my ($newbase, $wrecknotes, $base_q, @input_qs) = @_;
     # $base_q{SeriesBase}  $input_qs[]{SeriesBase}
     # $base_q{SeriesTip}   $input_qs[]{SeriesTip}
     # ^ specifies several patch series (currently we only support exactly 2)
@@ -1029,6 +1029,11 @@ sub walk ($;$$$) {
 	fail "something useful about failed merge attempt @_ xxx".Dumper($cl);
     };
 
+    my $mwrecknote = sub {
+	my ($reftail, $commitish) = @_;
+	$cl->{MergeWreckNotes}{$reftail} = $commitish;
+    };
+
     my $last_anchor;
 
     for (;;) {
@@ -1178,6 +1183,8 @@ sub walk ($;$$$) {
 
 	    my $ps = $cl->{Parents};
 
+	    $mwrecknote->('vanilla-merge', $cl->{CommitId});
+
 	    foreach my $p (@$ps) {
 		$prline->(" VanillaMerge ".$p->{Ix});
 		$prprdelim->();
@@ -1188,6 +1195,17 @@ sub walk ($;$$$) {
 		$p->{Breakwater} = $p->{SeriesBase} = $pbw;
 		$p->{Anchor} = $panchor;
 
+		my $lr = $p->{LeftRight} = (qw(left right))[$p->{Ix}];
+		$mwrecknote->("$lr-input", $p->{CommitId});
+
+		my $mwrecknote_parent = sub {
+		    my ($which) = @_;
+		    $mwrecknote->("$lr-".(lc $which), $p->{$which});
+		};
+		$mwrecknote_parent->('Laundered');
+		$mwrecknote_parent->('Breakwater');
+		$mwrecknote_parent->('Anchor');
+
 		$best_anchor = $panchor if
 		    !defined $best_anchor or
 		    is_fast_fwd $best_anchor, $panchor;
@@ -1196,10 +1214,12 @@ sub walk ($;$$$) {
 		    " p=$panchor\n";
 	    }
 
+	    $mwrecknote->('result-anchor', $best_anchor);
+
 	    foreach my $p (@$ps) {
 		$prline->(" VanillaMerge ".$p->{Ix});
 		if (!is_fast_fwd $p->{Anchor}, $best_anchor) {
-		    $nomerge->('DivergentAnchor');
+		    $nomerge->('divergent anchors');
 		} elsif ($p->{Anchor} eq $best_anchor) {
 		    print $report " SameAnchor" if $report;
 		} else {
@@ -1217,6 +1237,9 @@ sub walk ($;$$$) {
 	    }
 
 	    if ($ok && $might_be_in_bw) {
+		# We could rewrite this to contaion the metadata
+		# declaring it to be MergedBreakwaters, but
+		# unnecessarily rewriting a merge seems unhelpful.
 		$prline->(" VanillaMerge MergedBreakwaters");
 		$last_anchor = $best_anchor;
 		$build_start->('MergedBreakwaters', $cur);
@@ -1232,17 +1255,39 @@ sub walk ($;$$$) {
 	    # breakwater merge base as an ancestor.
 
 	    my @ibs =
-		grep { is_fast_fwd $bwb, $_ }
 		grep /./,
 		split /\n/,
 		cmdoutput @ibcmd;
-	    my ($ib) = @ibs
-		or $nomerge->("no suitable interchange merge base");
+
+            @ibs or confess 'internal error, expected anchor at least ?';
+
+	    my $ib;
+	    my $ibleaf;
+	    foreach my $tibix (0..$#ibs) {
+		my $tib = $ibs[$tibix];
+		my $ff = is_fast_fwd $bwb, $tib;
+		my $ok = !$ff ? 'rej' : $ib ? 'extra' : 'ok';
+		my $tibleaf = "interchange-mbcand-$ok-$tibix";
+		$mwrecknote->($tibleaf, $tib);
+		next unless $ff;
+		next if $ib;
+		$ib = $tib;
+		$ibleaf = $tibleaf;
+	    }
+
+	    $ib or $nomerge->("no suitable interchange merge base");
 
 	    $prline->("  VanillaMerge Base");
 	    $prprdelim->();
-	    my ($btip, $bbw, $banchor) =
+	    my ($btip, $bbw, $banchor) = eval {
 		walk $ib, 0, $report, $report_lprefix.'  ';
+	    };
+	    $nomerge->("walking interchange branch merge base ($ibleaf): ".
+		       $@) if length $@;
+
+	    $mwrecknote->("mergebase-laundered", $btip);
+	    $mwrecknote->("mergebase-breakwater", $bbw);
+	    $mwrecknote->("mergebase-anchor", $banchor);
 
 	    my $ibinfo = { SeriesTip => $btip,
 			   SeriesBase => $bbw,
@@ -1251,6 +1296,7 @@ sub walk ($;$$$) {
 		or $nomerge->("interchange merge-base ($ib)'s".
 			      " breakwater ($bbw)".
 			      " != breakwaters' merge-base ($bwb)");
+
 	    grep { $_->{Anchor} eq $ibinfo->{Anchor} } @$ps
 		 or $nomerge->("interchange merge-base ($ib)'s".
 			       " anchor ($ibinfo->{SeriesBase})".
@@ -1258,7 +1304,6 @@ sub walk ($;$$$) {
 			       (join ' ', map { $_->{Anchor} } @$ps).
 			       ")");
 
-
 	    $cl->{MergeInterchangeBaseInfo} = $ibinfo;
 	    $cl->{MergeBestAnchor} = $best_anchor;
 	    push @brw_cl, {
@@ -1347,7 +1392,7 @@ sub walk ($;$$$) {
 	    } elsif ($method eq 'MergeMergeSeries') {
 		print "Running merge resolution for $cl->{CommitId}...\n";
 		$build = merge_series
-		    $build,
+		    $build, $cl->{MergeWreckNotes},
 		    $cl->{MergeInterchangeBaseInfo},
 		    @{ $cl->{Parents} };
 		$last_anchor = $cl->{MergeBestAnchor};