[RFC/PATCH] Fix git-diff --cached to not error out if HEAD points to a nonexistant branch
From: Peter Baumann <hidden>
Date: 2016-06-15 22:42:56
Subsystem:
the rest · Maintainer:
Linus Torvalds
The documentation mentions "git-diff --cached" to see what is staged for
the next commit. But this failes if you haven't done any commits yet.
So lets fix it.
Signed-off-by: Peter Baumann <redacted>
---
I was bitten by this during explaining a total git newbie the index and
the several ways to diff index <-> wd, index <-> commit, commit <-> commit.
I posted this example
mkdir testrepo && cd testrepo
git init
echo foo > test.txt
git add test.txt
git diff --cached
usage: git-diff <options> <rev>{0,2} -- <path>*
and was totaly shocked to see the above error message.
I am not sure if this is the right fix and/or if git-diff-index
should also be fixed. I decided against it and let the core cmd git-diff-index
stay as it is now.
builtin-diff.c | 22 +++++++++++++++++++---
t/t4017-diff-cached.sh | 21 +++++++++++++++++++++
2 files changed, 40 insertions(+), 3 deletions(-)
create mode 100755 t/t4017-diff-cached.sh
diff --git a/builtin-diff.c b/builtin-diff.c
index c387ebb..aace507 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c@@ -203,11 +203,27 @@ void add_head(struct rev_info *revs) { unsigned char sha1[20]; struct object *obj; - if (get_sha1("HEAD", sha1)) + int ret = get_sha1("HEAD", sha1); + if (ret > 0) return; - obj = parse_object(sha1); - if (!obj) + + if (ret == 0) + obj = parse_object(sha1); + else { + /* HEAD exists but the branch it points to does not; + * we haven't done any commit yet => create an empty tree + * to make git diff --cached work + */ + obj = xcalloc(1, sizeof(struct object)); + obj->parsed = 1; + obj->type = OBJ_TREE; + + pretend_sha1_file(NULL, 0, tree_type, obj->sha1); + } + + if (!obj) { return; + } add_pending_object(revs, obj, "HEAD"); }
diff --git a/t/t4017-diff-cached.sh b/t/t4017-diff-cached.sh
new file mode 100755
index 0000000..39fc32f
--- /dev/null
+++ b/t/t4017-diff-cached.sh@@ -0,0 +1,21 @@ +#!/bin/sh +# +# Copyright (c) 2007 Peter Baumann +# + +test_description='Test diff --cached without inital commit. + +' +. ./test-lib.sh + +test_expect_success \ + 'setup' \ + 'echo frotz >rezrov && + git-update-index --add rezrov' + +test_expect_success \ + 'git-diff --cached' \ + 'git-diff --cached' + +test_done +
--
1.5.0.1.213.g509b-dirty