checkout: allow dwim for branch creation for "git checkout $branch --"

The "--" notation disambiguates files and branches, but as a side-effect
of the previous implementation, also disabled the branch auto-creation
when $branch does not exist.

A possible scenario is then:

git checkout $branch
=> fails if $branch is both a ref and a file, and suggests --

git checkout $branch --
=> refuses to create the $branch

This patch allows the second form to create $branch, and since the -- is
provided, it does not look for file named $branch.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/checkout.c b/builtin/checkout.c
index f5b50e520feb42c50cd1783871eb63d009e0a0e0..c98008ab488b7321bd76f83041dc679f919fe7c4 100644 (file)
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -884,20 +884,30 @@ static int parse_branchname_arg(int argc, const char **argv,
         *
         *   everything after the '--' must be paths.
         *
         *
         *   everything after the '--' must be paths.
         *

-        * case 3: git checkout <something> [<paths>]
+        * case 3: git checkout <something> [--]

         *
         *

-        *   With no paths, if <something> is a commit, that is to
-        *   switch to the branch or detach HEAD at it.  As a special case,
-        *   if <something> is A...B (missing A or B means HEAD but you can
-        *   omit at most one side), and if there is a unique merge base
-        *   between A and B, A...B names that merge base.
+        *   (a) If <something> is a commit, that is to
+        *       switch to the branch or detach HEAD at it.  As a special case,
+        *       if <something> is A...B (missing A or B means HEAD but you can
+        *       omit at most one side), and if there is a unique merge base
+        *       between A and B, A...B names that merge base.

         *
         *

-        *   With no paths, if <something> is _not_ a commit, no -t nor -b
-        *   was given, and there is a tracking branch whose name is
-        *   <something> in one and only one remote, then this is a short-hand
-        *   to fork local <something> from that remote-tracking branch.
+        *   (b) If <something> is _not_ a commit, either "--" is present
+        *       or <something> is not a path, no -t nor -b was given, and
+        *       and there is a tracking branch whose name is <something>
+        *       in one and only one remote, then this is a short-hand to
+        *       fork local <something> from that remote-tracking branch.

         *
         *

-        *   Otherwise <something> shall not be ambiguous.
+        *   (c) Otherwise, if "--" is present, treat it like case (1).
+        *
+        *   (d) Otherwise :
+        *       - if it's a reference, treat it like case (1)
+        *       - else if it's a path, treat it like case (2)
+        *       - else: fail.
+        *
+        * case 4: git checkout <something> <paths>
+        *
+        *   The first argument must not be ambiguous.

         *   - If it's *only* a reference, treat it like case (1).
         *   - If it's only a path, treat it like case (2).
         *   - else: fail.
         *   - If it's *only* a reference, treat it like case (1).
         *   - If it's only a path, treat it like case (2).
         *   - else: fail.


@@ -916,18 +926,40 @@ static int parse_branchname_arg(int argc, const char **argv,
                arg = "@{-1}";
 
        if (get_sha1_mb(arg, rev)) {
                arg = "@{-1}";
 
        if (get_sha1_mb(arg, rev)) {

-               if (has_dash_dash)          /* case (1) */
-                       die(_("invalid reference: %s"), arg);
-               if (dwim_new_local_branch_ok &&
-                   !check_filename(NULL, arg) &&
-                   argc == 1) {
+               /*
+                * Either case (3) or (4), with <something> not being
+                * a commit, or an attempt to use case (1) with an
+                * invalid ref.
+                *
+                * It's likely an error, but we need to find out if
+                * we should auto-create the branch, case (3).(b).
+                */
+               int recover_with_dwim = dwim_new_local_branch_ok;
+
+               if (check_filename(NULL, arg) && !has_dash_dash)
+                       recover_with_dwim = 0;
+               /*
+                * Accept "git checkout foo" and "git checkout foo --"
+                * as candidates for dwim.
+                */
+               if (!(argc == 1 && !has_dash_dash) &&
+                   !(argc == 2 && has_dash_dash))
+                       recover_with_dwim = 0;
+
+               if (recover_with_dwim) {

                        const char *remote = unique_tracking_name(arg, rev);
                        const char *remote = unique_tracking_name(arg, rev);

-                       if (!remote)
-                               return argcount;
-                       *new_branch = arg;
-                       arg = remote;
-                       /* DWIMmed to create local branch */
-               } else {
+                       if (remote) {
+                               *new_branch = arg;
+                               arg = remote;
+                               /* DWIMmed to create local branch, case (3).(b) */
+                       } else {
+                               recover_with_dwim = 0;
+                       }
+               }
+
+               if (!recover_with_dwim) {
+                       if (has_dash_dash)
+                               die(_("invalid reference: %s"), arg);

                        return argcount;
                }
        }
                        return argcount;
                }
        }


@@ -957,7 +989,7 @@ static int parse_branchname_arg(int argc, const char **argv,
 
        if (!*source_tree)                   /* case (1): want a tree */
                die(_("reference is not a tree: %s"), arg);
 
        if (!*source_tree)                   /* case (1): want a tree */
                die(_("reference is not a tree: %s"), arg);

-       if (!has_dash_dash) {/* case (3 -> 1) */
+       if (!has_dash_dash) {/* case (3).(d) -> (1) */

                /*
                 * Do not complain the most common case
                 *      git checkout branch
                /*
                 * Do not complain the most common case
                 *      git checkout branch

diff --git a/t/t2024-checkout-dwim.sh b/t/t2024-checkout-dwim.sh
index dee55e428f07eeac9c2d2c329ff2c1aca3f4ea98..36be80fd41a7301fad657b33f028af844add60f8 100755 (executable)
--- a/t/t2024-checkout-dwim.sh
+++ b/t/t2024-checkout-dwim.sh
@@ -164,4 +164,25 @@ test_expect_success 'checkout of branch from a single remote succeeds #4' '
        test_branch_upstream eggs repo_d eggs
 '
 
        test_branch_upstream eggs repo_d eggs
 '
 

+test_expect_success 'checkout of branch with a file having the same name fails' '
+       git checkout -B master &&
+       test_might_fail git branch -D spam &&
+
+       >spam &&
+       test_must_fail git checkout spam &&
+       test_must_fail git rev-parse --verify refs/heads/spam &&
+       test_branch master
+'
+
+test_expect_success 'checkout <branch> -- succeeds, even if a file with the same name exists' '
+       git checkout -B master &&
+       test_might_fail git branch -D spam &&
+
+       >spam &&
+       git checkout spam -- &&
+       test_branch spam &&
+       test_cmp_rev refs/remotes/extra_dir/repo_c/extra_dir/spam HEAD &&
+       test_branch_upstream spam repo_c spam
+'
+

 test_done
 test_done