Introduce CHERRY_PICK_HEAD

When a cherry-pick conflicts git advises:

 $ git commit -c <original commit id>

to preserve the original commit message and authorship. Instead, let's
record the original commit id in CHERRY_PICK_HEAD and advise:

  $ git commit -c CHERRY_PICK_HEAD

A later patch teaches git to handle the '-c CHERRY_PICK_HEAD' part.
Note that we record CHERRY_PICK_HEAD even in the case where there
are no conflicts so that we may use it to communicate authorship to
commit; this will then allow us to remove set_author_ident_env from
revert.c. However, we do not record CHERRY_PICK_HEAD when --no-commit
is used, as presumably the user intends to further edit the commit
and possibly even cherry-pick additional commits on top.

Tests and documentation contributed by Jonathan Nieder.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 73008705ebe304c8d2a2d089e9328be369c50fc6..cd848664ce05e60b866ebd2d6b875ae0416626f0 100644 (file)
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -16,6 +16,25 @@ Given one or more existing commits, apply the change each one
 introduces, recording a new commit for each.  This requires your
 working tree to be clean (no modifications from the HEAD commit).
 
+When it is not obvious how to apply a change, the following
+happens:
+
+1. The current branch and `HEAD` pointer stay at the last commit
+   successfully made.
+2. The `CHERRY_PICK_HEAD` ref is set to point at the commit that
+   introduced the change that is difficult to apply.
+3. Paths in which the change applied cleanly are updated both
+   in the index file and in your working tree.
+4. For conflicting paths, the index file records up to three
+   versions, as described in the "TRUE MERGE" section of
+   linkgit:git-merge[1].  The working tree files will include
+   a description of the conflict bracketed by the usual
+   conflict markers `<<<<<<<` and `>>>>>>>`.
+5. No other modifications are made.
+
+See linkgit:git-merge[1] for some hints on resolving such
+conflicts.
+
 OPTIONS
 -------
 <commit>...::

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index 9e92734bc1b308c47e5f5726c704a3ddffa5beb9..04fceee2535d91b9cec9157e5219a81fc63a5dce 100644 (file)
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -25,7 +25,8 @@ blobs contained in a commit.
   first match in the following rules:
 
   . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
-    useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD` and `MERGE_HEAD`);
+    useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD`, `MERGE_HEAD`
+    and `CHERRY_PICK_HEAD`);
 
   . otherwise, `refs/<name>` if exists;
 
@@ -46,6 +47,8 @@ you can change the tip of the branch back to the state before you ran
 them easily.
 MERGE_HEAD records the commit(s) you are merging into your branch
 when you run 'git merge'.
+CHERRY_PICK_HEAD records the commit you are cherry-picking
+when you run 'git cherry-pick'.
 +
 Note that any of the `refs/*` cases above may come either from
 the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file.

diff --git a/branch.c b/branch.c
index 93dc866f8c09a2da2308c4fd677178b043f2d4d5..dc23e954357c7e56d9232af7a8907ec4ed15b674 100644 (file)
--- a/branch.c
+++ b/branch.c
@@ -217,6 +217,7 @@ void create_branch(const char *head,
 
 void remove_branch_state(void)
 {
+       unlink(git_path("CHERRY_PICK_HEAD"));
        unlink(git_path("MERGE_HEAD"));
        unlink(git_path("MERGE_RR"));
        unlink(git_path("MERGE_MSG"));

diff --git a/builtin/commit.c b/builtin/commit.c
index 03cff5af631fec975442c528b1ffba264b879c8e..0def5401abdd511afa58b2e5cbc1274786c563db 100644 (file)
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1424,6 +1424,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
                die("cannot update HEAD ref");
        }
 
+       unlink(git_path("CHERRY_PICK_HEAD"));
        unlink(git_path("MERGE_HEAD"));
        unlink(git_path("MERGE_MSG"));
        unlink(git_path("MERGE_MODE"));

diff --git a/builtin/merge.c b/builtin/merge.c
index 42fff387e69d9b5412e8e776aed3272b78ebe758..5ba2efc21439b3150f3c46552fea10a0922773e1 100644 (file)
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -969,6 +969,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                else
                        die("You have not concluded your merge (MERGE_HEAD exists).");
        }
+       if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
+               if (advice_resolve_conflict)
+                       die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
+                           "Please, commit your changes before you can merge.");
+               else
+                       die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).");
+       }
        resolve_undo_clear();
 
        if (verbosity < 0)

diff --git a/builtin/revert.c b/builtin/revert.c
index bb6e9e83b756b47dae449064ca7762fe3558fc0e..e716a1b0001049262c20cabe14a7d88aa9f78acf 100644 (file)
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -231,6 +231,22 @@ static void set_author_ident_env(const char *message)
                        sha1_to_hex(commit->object.sha1));
 }
 
+static void write_cherry_pick_head(void)
+{
+       int fd;
+       struct strbuf buf = STRBUF_INIT;
+
+       strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
+
+       fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
+       if (fd < 0)
+               die_errno("Could not open '%s' for writing",
+                         git_path("CHERRY_PICK_HEAD"));
+       if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
+               die_errno("Could not write to '%s'", git_path("CHERRY_PICK_HEAD"));
+       strbuf_release(&buf);
+}
+
 static void advise(const char *advice, ...)
 {
        va_list params;
@@ -246,6 +262,12 @@ static void print_advice(void)
 
        if (msg) {
                fprintf(stderr, "%s\n", msg);
+               /*
+                * A conflict has occured but the porcelain
+                * (typically rebase --interactive) wants to take care
+                * of the commit itself so remove CHERRY_PICK_HEAD
+                */
+               unlink(git_path("CHERRY_PICK_HEAD"));
                return;
        }
 
@@ -253,8 +275,7 @@ static void print_advice(void)
        advise("with 'git add <paths>' or 'git rm <paths>'");
 
        if (action == CHERRY_PICK)
-               advise("and commit the result with 'git commit -c %s'",
-                      find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
+               advise("and commit the result with 'git commit -c CHERRY_PICK_HEAD'");
 }
 
 static void write_message(struct strbuf *msgbuf, const char *filename)
@@ -489,6 +510,8 @@ static int do_pick_commit(void)
                        strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
                        strbuf_addstr(&msgbuf, ")\n");
                }
+               if (!no_commit)
+                       write_cherry_pick_head();
        }
 
        if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {

diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index 2313d79bd417858911a9efbf99adaa57f03b5bd0..e0bf3563ac1a864129e0739d84f11c9eac9f0882 100755 (executable)
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -52,13 +52,87 @@ test_expect_success 'advice from failed cherry-pick' "
        error: could not apply \$picked... picked
        hint: after resolving the conflicts, mark the corrected paths
        hint: with 'git add <paths>' or 'git rm <paths>'
-       hint: and commit the result with 'git commit -c \$picked'
+       hint: and commit the result with 'git commit -c CHERRY_PICK_HEAD'
        EOF
        test_must_fail git cherry-pick picked 2>actual &&
 
        test_cmp expected actual
 "
 
+test_expect_success 'failed cherry-pick sets CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+       test_must_fail git cherry-pick picked &&
+       test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'successful cherry-pick does not set CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+       git cherry-pick base &&
+       test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'cherry-pick --no-commit does not set CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+       git cherry-pick --no-commit base &&
+       test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'GIT_CHERRY_PICK_HELP suppresses CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+       (
+               GIT_CHERRY_PICK_HELP="and then do something else" &&
+               export GIT_CHERRY_PICK_HELP &&
+               test_must_fail git cherry-pick picked
+       ) &&
+       test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'git reset clears CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+
+       test_must_fail git cherry-pick picked &&
+       git reset &&
+
+       test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'failed commit does not clear CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+
+       test_must_fail git cherry-pick picked &&
+       test_must_fail git commit &&
+
+       test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'cancelled commit does not clear CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+
+       test_must_fail git cherry-pick picked &&
+       echo resolved >foo &&
+       git add foo &&
+       git update-index --refresh -q &&
+       test_must_fail git diff-index --exit-code HEAD &&
+       (
+               GIT_EDITOR=false &&
+               export GIT_EDITOR &&
+               test_must_fail git commit
+       ) &&
+
+       test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'successful commit clears CHERRY_PICK_HEAD' '
+       pristine_detach initial &&
+
+       test_must_fail git cherry-pick picked &&
+       echo resolved >foo &&
+       git add foo &&
+       git commit &&
+
+       test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
 test_expect_success 'failed cherry-pick produces dirty index' '
        pristine_detach initial &&