add--interactive: handle initial commit better

There were several points where we looked at the HEAD
commit; for initial commits, this is meaningless. So instead
we:

  - show staged status data as a diff against the empty tree
    instead of HEAD
  - show file diffs as creation events
  - use "git rm --cached" to revert instead of going back to
    the HEAD commit

We magically reference the empty tree to implement this.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-add--interactive.perl b/git-add--interactive.perl
index 17ca5b84f0c077d61b9392bd7900954ce35d6cbf..a0a81f134a6288dfc1d87431698f29597ed5e488 100755 (executable)
--- a/git-add--interactive.perl
+++ b/git-add--interactive.perl
@@ -82,6 +82,19 @@ sub list_untracked {
 my $status_fmt = '%12s %12s %s';
 my $status_head = sprintf($status_fmt, 'staged', 'unstaged', 'path');
 
+{
+       my $initial;
+       sub is_initial_commit {
+               $initial = system('git rev-parse HEAD -- >/dev/null 2>&1') != 0
+                       unless defined $initial;
+               return $initial;
+       }
+}
+
+sub get_empty_tree {
+       return '4b825dc642cb6eb9a060e54bf8d69288fbee4904';
+}
+
 # Returns list of hashes, contents of each of which are:
 # VALUE:       pathname
 # BINARY:      is a binary path
@@ -103,8 +116,10 @@ sub list_modified {
                return if (!@tracked);
        }
 
+       my $reference = is_initial_commit() ? get_empty_tree() : 'HEAD';
        for (run_cmd_pipe(qw(git diff-index --cached
-                            --numstat --summary HEAD --), @tracked)) {
+                            --numstat --summary), $reference,
+                            '--', @tracked)) {
                if (($add, $del, $file) =
                    /^([-\d]+)  ([-\d]+)        (.*)/) {
                        my ($change, $bin);
@@ -476,21 +491,27 @@ sub revert_cmd {
                                       HEADER => $status_head, },
                                     list_modified());
        if (@update) {
-               my @lines = run_cmd_pipe(qw(git ls-tree HEAD --),
-                                        map { $_->{VALUE} } @update);
-               my $fh;
-               open $fh, '| git update-index --index-info'
-                   or die;
-               for (@lines) {
-                       print $fh $_;
+               if (is_initial_commit()) {
+                       system(qw(git rm --cached),
+                               map { $_->{VALUE} } @update);
                }
-               close($fh);
-               for (@update) {
-                       if ($_->{INDEX_ADDDEL} &&
-                           $_->{INDEX_ADDDEL} eq 'create') {
-                               system(qw(git update-index --force-remove --),
-                                      $_->{VALUE});
-                               print "note: $_->{VALUE} is untracked now.\n";
+               else {
+                       my @lines = run_cmd_pipe(qw(git ls-tree HEAD --),
+                                                map { $_->{VALUE} } @update);
+                       my $fh;
+                       open $fh, '| git update-index --index-info'
+                           or die;
+                       for (@lines) {
+                               print $fh $_;
+                       }
+                       close($fh);
+                       for (@update) {
+                               if ($_->{INDEX_ADDDEL} &&
+                                   $_->{INDEX_ADDDEL} eq 'create') {
+                                       system(qw(git update-index --force-remove --),
+                                              $_->{VALUE});
+                                       print "note: $_->{VALUE} is untracked now.\n";
+                               }
                        }
                }
                refresh();
@@ -956,7 +977,9 @@ sub diff_cmd {
                                     HEADER => $status_head, },
                                   @mods);
        return if (!@them);
-       system(qw(git diff -p --cached HEAD --), map { $_->{VALUE} } @them);
+       my $reference = is_initial_commit() ? get_empty_tree() : 'HEAD';
+       system(qw(git diff -p --cached), $reference, '--',
+               map { $_->{VALUE} } @them);
 }
 
 sub quit_cmd {

diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
new file mode 100755 (executable)
index 0000000..c8dc1ac
--- /dev/null
+++ b/t/t3701-add-interactive.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+test_description='add -i basic tests'
+. ./test-lib.sh
+
+test_expect_success 'setup (initial)' '
+       echo content >file &&
+       git add file &&
+       echo more >>file &&
+       echo lines >>file
+'
+test_expect_success 'status works (initial)' '
+       git add -i </dev/null >output &&
+       grep "+1/-0 *+2/-0 file" output
+'
+cat >expected <<EOF
+new file mode 100644
+index 0000000..d95f3ad
+--- /dev/null
++++ b/file
+@@ -0,0 +1 @@
++content
+EOF
+test_expect_success 'diff works (initial)' '
+       (echo d; echo 1) | git add -i >output &&
+       sed -ne "/new file/,/content/p" <output >diff &&
+       diff -u expected diff
+'
+test_expect_success 'revert works (initial)' '
+       git add file &&
+       (echo r; echo 1) | git add -i &&
+       git ls-files >output &&
+       ! grep . output
+'
+
+test_expect_success 'setup (commit)' '
+       echo baseline >file &&
+       git add file &&
+       git commit -m commit &&
+       echo content >>file &&
+       git add file &&
+       echo more >>file &&
+       echo lines >>file
+'
+test_expect_success 'status works (commit)' '
+       git add -i </dev/null >output &&
+       grep "+1/-0 *+2/-0 file" output
+'
+cat >expected <<EOF
+index 180b47c..b6f2c08 100644
+--- a/file
++++ b/file
+@@ -1 +1,2 @@
+ baseline
++content
+EOF
+test_expect_success 'diff works (commit)' '
+       (echo d; echo 1) | git add -i >output &&
+       sed -ne "/^index/,/content/p" <output >diff &&
+       diff -u expected diff
+'
+test_expect_success 'revert works (commit)' '
+       git add file &&
+       (echo r; echo 1) | git add -i &&
+       git add -i </dev/null >output &&
+       grep "unchanged *+3/-0 file" output
+'
+
+test_done