[PATCH] vcs_info git: Fix stagedstr for empty repos

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Good morning Frank, *,

vcs_info git false-negatives to detect staged changes in a repository that has
no commits.  Attached a patch for that.

The patch includes two variants for computing the "has staged changes?" bit in
empty repositories: one via 'git ls-files' and one via git's empty tree.

- The output of ls-files isn't O(1), but I tested with a 3000-file tree and
  didn't notice a slowdown, so I suppose it's acceptable.

- 'diff-index --cached --quiet $empty_tree' is an O(1) operation, but I am not
  sure whether it is forwards compatible with future versions of Git, i.e.,
  whether it's a hack that happens to work or a legitimate use of git's API.

WDYT?

Daniel

From 9994132f33c5439fbb5d3c4ef91ba122b942fd7c Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>
Date: Fri, 30 May 2014 23:50:55 +0000
Subject: [PATCH 2/2] vcs_info git: Fix stagedstr for empty repos

In empty repositories, HEAD is an unresolvable symbolic ref.  Start computing
stagedstr/unstagedstr in that case; for the former, use a different method
than the non-empty-repository case.
---
 Functions/VCS_Info/Backends/VCS_INFO_get_data_git |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
index a48dc39..caf938b 100644
--- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
+++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_git
@@ -128,16 +128,25 @@ elif zstyle -t ":vcs_info:${vcs}:${usercontext}:${rrn}" "check-for-staged-change
     querystaged=1
 fi
 if (( querystaged || queryunstaged )) && \
-   [[ "$(${vcs_comm[cmd]} rev-parse --is-inside-git-dir 2> /dev/null)" != 'true' ]] && \
-   ${vcs_comm[cmd]} rev-parse --quiet --verify HEAD &> /dev/null ; then
+   [[ "$(${vcs_comm[cmd]} rev-parse --is-inside-work-tree 2> /dev/null)" == 'true' ]] ; then
     # Default: off - these are potentially expensive on big repositories
     if (( queryunstaged )) ; then
         ${vcs_comm[cmd]} diff --no-ext-diff --ignore-submodules --quiet --exit-code ||
             gitunstaged=1
     fi
     if (( querystaged )) ; then
-        ${vcs_comm[cmd]} diff-index --cached --quiet --ignore-submodules HEAD 2> /dev/null
-        (( $? && $? != 128 )) && gitstaged=1
+        if ${vcs_comm[cmd]} rev-parse --quiet --verify HEAD &> /dev/null ; then
+            ${vcs_comm[cmd]} diff-index --cached --quiet --ignore-submodules HEAD 2> /dev/null
+            (( $? && $? != 128 )) && gitstaged=1
+        else
+            # empty repository (no commits yet)
+            # TODO: ls-files' output isn't O(1); might be faster to use
+            #         empty_tree_sha1=$(git hash-object -t tree /dev/null)
+            #         git diff-index --cached --quiet $empty_tree_sha1
+            #         (( $? && $? != 128 ))
+            #       to efficiently get the "is the index not empty?" bit.
+            [[ -n "$(${vcs_comm[cmd]} ls-files --cached -z)" ]] && gitstaged=1
+        fi
     fi
 fi
 
-- 
1.7.10.4