git-debrebase: do not bomb on totally ambiguous pseudomerges

[dgit.git] / git-debrebase

diff --git a/git-debrebase b/git-debrebase
index 32737269a48120fa3f55720d8b778ca618ad3858..932a3b7a6aed3b67fe40d9846aa5366da1432d78 100755 (executable)
--- a/git-debrebase
+++ b/git-debrebase
@@ -28,11 +28,13 @@
 #
 #    git-debrebase [<options> --] [<git-rebase options...>]
 #    git-debrebase [<options>] analyse
+#    git-debrebase [<options>] breakwater      # prints breakwater tip only
 #    git-debrebase [<options>] launder         # prints breakwater tip etc.
 #    git-debrebase [<options>] stitch [--prose=<for commit message>]
 #    git-debrebase [<options>] downstream-rebase-launder-v0  # experimental
 #
-#    git-debrebase [<options>] convert-from-gbp <upstream-git-rev>
+#    git-debrebase [<options>] convert-from-gbp [<upstream-git-rev>]
+#    git-debrebase [<options>] convert-to-gbp
 
 # problems / outstanding questions:
 #
@@ -448,15 +450,24 @@ sub classify ($) {
                           Contributor => $identical[0]);
     }
     if (@p == 2 && @identical == 2) {
-       my @bytime = nsort_by {
-           my ($ph,$pm) = get_commit $_->{CommitId};
+       my $get_t = sub {
+           my ($ph,$pm) = get_commit $_[0]{CommitId};
            $ph =~ m/^committer .* (\d+) [-+]\d+$/m or die "$_->{CommitId} ?";
            $1;
-       } @p;
+       };
+       my @bytime = @p;
+       my $order = $get_t->($bytime[0]) <=> $get_t->($bytime[1]);
+       if ($order > 0) { # newer first
+       } elsif ($order < 0) {
+           @bytime = reverse @bytime;
+       } else {
+           # same age, default to order made by -s ours
+           # that is, commit was made by someone who preferred L
+       }
        return $classify->(qw(Pseudomerge),
                           SubType => qw(Ambiguous),
-                          Overwritten => [ $bytime[0] ],
-                          Contributor => $bytime[1]);
+                          Contributor => $bytime[0],
+                          Overwritten => [ $bytime[1] ]);
     }
     foreach my $p (@p) {
        my ($p_h, $p_m) = get_commit $p->{CommitId};
@@ -508,6 +519,42 @@ sub classify ($) {
     return $unknown->("complex merge");
 }
 
+sub breakwater_of ($) {
+    my ($head) = @_; # must be laundered
+    my $breakwater;
+    my $unclean = sub {
+       my ($why) = @_;
+       fail "branch needs laundering (run git-debrebase): $why";
+    };
+    for (;;) {
+       my $cl = classify $head;
+       my $ty = $cl->{Type};
+       if ($ty eq 'Packaging' or
+           $ty eq 'Changelog') {
+           $breakwater //= $head;
+       } elsif ($ty eq 'BreakwaterUpstreamMerge' or
+                $ty eq 'BreakwaterStart') {
+           $breakwater //= $head;
+           last;
+       } elsif ($ty eq 'Upstream') {
+           $unclean->("packaging change ($breakwater)".
+                      " follows upstream change (eg $head)")
+               if defined $breakwater;
+       } elsif ($ty eq 'Mixed') {
+           $unclean->('found mixed upstream/packaging commit ($head)');
+       } elsif ($ty eq 'Pseudomerge' or
+                $ty eq 'AddPatches') {
+           $unclean->("found interchange conversion commit ($ty, $head)");
+       } elsif ($ty eq 'DgitImportUnpatched') {
+           $unclean->("found dgit dsc import ($head)");
+       } else {
+           fail "found unprocessable commit, cannot cope: $head; $cl->{Why}";
+       }
+       $head = $cl->{Parents}[0]{CommitId};
+    }
+    return $breakwater;
+}
+
 sub walk ($;$$);
 sub walk ($;$$) {
     my ($input,
@@ -552,13 +599,16 @@ sub walk ($;$$) {
 
     my $bomb = sub { # usage: return $bomb->();
        print $report " Unprocessable" if $report;
+       print $report " ($cl->{Why})" if $report && defined $cl->{Why};
        $prprdelim->();
        if ($nogenerate) {
            return (undef,undef);
        }
        die "commit $cur: Cannot cope with this commit (d.".
            (join ' ', map { sprintf "%#x", $_->{Differs} }
-            @{ $cl->{Parents} }). ")";
+            @{ $cl->{Parents} }).
+           (defined $cl->{Why} ? "; $cl->{Why}": '').
+                ")";
     };
 
     my $build;
@@ -1133,6 +1183,12 @@ sub cmd_record_ffq_prev () {
     }
 }
 
+sub cmd_breakwater () {
+    badusage "no arguments allowed" if @ARGV;
+    my $bw = breakwater_of git_rev_parse 'HEAD';
+    print "$bw\n" or die $!;
+}
+
 sub cmd_stitch () {
     my $prose = '';
     GetOptions('prose=s', \$prose) or die badusage("bad options to stitch");
@@ -1234,6 +1290,36 @@ sub cmd_convert_from_gbp () {
     update_head_checkout $old_head, $work, 'convert-from-gbp';
 }
 
+sub cmd_convert_to_gbp () {
+    badusage "no arguments allowed" if @ARGV;
+    my $head = get_head();
+    my $ffq = (ffq_prev_branchinfo())[3];
+    my $bw = breakwater_of $head;
+    fresh_workarea();
+    my $out;
+    in_workarea sub {
+       runcmd @git, qw(checkout -q -b bw), $bw;
+       runcmd @git, qw(checkout -q -b patch-queue/bw), $head;
+       runcmd qw(gbp pq export);
+       runcmd @git, qw(add debian/patches);
+       $out = make_commit ['HEAD'], [
+            'Commit patch queue (converted from git-debrebase format)',
+            '[git-debrebase convert-to-gbp: commit patches]',
+        ];
+    };
+    if (defined $ffq) {
+       runcmd @git, qw(update-ref -m),
+           "debrebase: converting corresponding main branch to gbp format",
+           $ffq, $git_null_obj;
+    }
+    update_head_checkout $head, $out, "convert to gbp (v0)";
+    print <<END or die $!;
+git-debrebase: converted to git-buildpackage branch format
+git-debrebase: WARNING: do not now run "git-debrebase" any more
+git-debrebase: WARNING: doing so would drop all upstream patches!
+END
+}
+
 sub cmd_downstream_rebase_launder_v0 () {
     badusage "needs 1 argument, the baseline" unless @ARGV==1;
     my ($base) = @ARGV;