dgit: Internal change: Support forcing split source builds

We are going to start handling weirder kinds of git tree, which will
require a kind of `split brain': the dgit-using maintainer's view will
be a git tree which is not a dgit git tree.  dgit will convert them
during push.

For this to work we will have to have dgit always (in these cases)
generate the source package itself (with a separate invocation of
dpkg-source).  This will involve some dis- and re-entangling of the
way we generate arguments to dpkg-buildpackage.

We can profitably split this up into this pre-patch, which has no
overall functional change for normal users.

We do here provide a new --always-split-source-build option which
allows the new approach to be explicitly requested.  This allows us to
use the test suite to not only test that we didn't break any of the
existing building strategies, but also that the new strategies all do
what we expect.

But this option is not really semantically useful for users so we do
not document it.

1 files changed, 72 insertions, 23 deletions

diff --git a/dgit b/dgit
index 6a15393..ae75cb9 100755
--- a/dgit
+++ b/dgit
@@ -113,6 +113,7 @@ our $keyid;
 autoflush STDOUT 1;
 
 our $supplementary_message = '';
+our $need_split_build_invocation = 0;
 
 END {
     local ($@, $?);
@@ -3058,33 +3059,73 @@ sub changesopts () {
 
 sub massage_dbp_args ($;$) {
     my ($cmd,$xargs) = @_;
-    if ($cleanmode eq 'dpkg-source') {
+    # We need to:
+    #
+    #  - if we're going to split the source build out so we can
+    #    do strange things to it, massage the arguments to dpkg-buildpackage
+    #    so that the main build doessn't build source (or add an argument
+    #    to stop it building source by default).
+    #
+    #  - add -nc to stop dpkg-source cleaning the source tree,
+    #    unless we're not doing a split build and want dpkg-source
+    #    as cleanmode, in which case we can do nothing
+    #
+    # return values:
+    #    0 - source will NOT need to be built separately by caller
+    #   +1 - source will need to be built separately by caller
+    #   +2 - source will need to be built separately by caller AND
+    #        dpkg-buildpackage should not in fact be run at all!
+    debugcmd '#massaging#', @$cmd if $debuglevel>1;
+#print STDERR "MASS0 ",Dumper($cmd, $xargs, $need_split_build_invocation);
+    if ($cleanmode eq 'dpkg-source' && !$need_split_build_invocation) {
 	$suppress_clean = 1;
-	return;
+	return 0;
     }
-    debugcmd '#massaging#', @$cmd if $debuglevel>1;
-    my @newcmd = shift @$cmd;
     # -nc has the side effect of specifying -b if nothing else specified
-    push @newcmd, '-nc';
     # and some combinations of -S, -b, et al, are errors, rather than
-    # later simply overriding earlier
-    push @newcmd, '-F' unless grep { m/^-[bBASFgG]$/ } (@$cmd, @$xargs);
-    push @newcmd, @$cmd;
-    @$cmd = @newcmd;
+    # later simply overriding earlie.  So we need to:
+    #  - search the command line for these options
+    #  - pick the last one
+    #  - perhaps add our own as a default
+    #  - perhaps adjust it to the corresponding non-source-building version
+    my $dmode = '-F';
+    foreach my $l ($cmd, $xargs) {
+	next unless $l;
+	@$l = grep { !(m/^-[SgGFABb]$/s and $dmode=$_) } @$l;
+    }
+    push @$cmd, '-nc';
+#print STDERR "MASS1 ",Dumper($cmd, $xargs, $dmode);
+    my $r = 0;
+    if ($need_split_build_invocation) {
+	$r = $dmode =~ m/[S]/     ? +2 :
+	     $dmode =~ y/gGF/ABb/ ? +1 :
+	     $dmode =~ m/[ABb]/   ?  0 :
+	     die "$dmode ?";
+    }
+    push @$cmd, $dmode;
+#print STDERR "MASS2 ",Dumper($cmd, $xargs, $r);
+    return $r;
 }
 
 sub cmd_build {
     my @dbp = (@dpkgbuildpackage, qw(-us -uc), changesopts_initial(), @ARGV);
-    massage_dbp_args \@dbp;
-    build_prep();
-    push @dbp, changesopts_version();
-    runcmd_ordryrun_local @dbp;
+    my $wantsrc = massage_dbp_args \@dbp;
+    if ($wantsrc > 0) {
+	build_source();
+    } else {
+	build_prep();
+    }
+    if ($wantsrc < 2) {
+	push @dbp, changesopts_version();
+	runcmd_ordryrun_local @dbp;
+    }
     printdone "build successful\n";
 }
 
 sub cmd_gbp_build {
     my @dbp = @dpkgbuildpackage;
-    massage_dbp_args \@dbp, \@ARGV;
+
+    my $wantsrc = massage_dbp_args \@dbp, \@ARGV;
 
     my @cmd;
     if (length executable_on_path('git-buildpackage')) {
@@ -3094,18 +3135,22 @@ sub cmd_gbp_build {
     }
     push @cmd, (qw(-us -uc --git-no-sign-tags), "--git-builder=@dbp");
 
-    if ($cleanmode eq 'dpkg-source') {
-	$suppress_clean = 1;
+    if ($wantsrc > 0) {
+	build_source();
     } else {
-	push @cmd, '--git-cleaner=true';
+	if (!$suppress_clean) {
+	    push @cmd, '--git-cleaner=true';
+	}
+	build_prep();
     }
-    build_prep();
-    unless (grep { m/^--git-debian-branch|^--git-ignore-branch/ } @ARGV) {
-	canonicalise_suite();
-	push @cmd, "--git-debian-branch=".lbranch();
+    if ($wantsrc < 2) {
+	unless (grep { m/^--git-debian-branch|^--git-ignore-branch/ } @ARGV) {
+	    canonicalise_suite();
+	    push @cmd, "--git-debian-branch=".lbranch();
+	}
+	push @cmd, changesopts();
+	runcmd_ordryrun_local @cmd, @ARGV;
     }
-    push @cmd, changesopts();
-    runcmd_ordryrun_local @cmd, @ARGV;
     printdone "build successful\n";
 }
 sub cmd_git_build { cmd_gbp_build(); } # compatibility with <= 1.0
@@ -3352,6 +3397,10 @@ sub parseopts () {
 	    } elsif (m/^--deliberately-($deliberately_re)$/s) {
 		push @ropts, $_;
 		push @deliberatelies, $&;
+	    } elsif (m/^--always-split-source-build$/s) {
+		# undocumented, for testing
+		push @ropts, $_;
+		$need_split_build_invocation = 1;
 	    } elsif (m/^(--[-0-9a-z]+)(=|$)/ && ($oi = $valopts_long{$1})) {
 		$val = $2 ? $' : undef; #';
 		$valopt->($oi->{Long});