specifying ranges: we did not mean to make ".." an empty set

Either end of revision range operator can be omitted to default to HEAD,
as in "origin.." (what did I do since I forked) or "..origin" (what did
they do since I forked).  But the current parser interprets ".."  as an
empty range "HEAD..HEAD", and worse yet, because ".." does exist on the
filesystem, we get this annoying output:

  $ cd Documentation/howto
  $ git log .. ;# give me recent commits that touch Documentation/ area.
  fatal: ambiguous argument '..': both revision and filename
  Use '--' to separate filenames from revisions

Surely we could say "git log ../" or even "git log -- .." to disambiguate,
but we shouldn't have to.

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

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index dc0070bcb7ec2f4e6773066ffb745967d9df6fb3..69d996bc3899a89de49b0cbdf65f5b8ebd47d714 100644 (file)
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -213,6 +213,13 @@ of 'r1' and 'r2' and is defined as
 It is the set of commits that are reachable from either one of
 'r1' or 'r2' but not from both.
 
+In these two shorthands, you can omit one end and let it default to HEAD.
+For example, 'origin..' is a shorthand for 'origin..HEAD' and asks "What
+did I do since I forked from the origin branch?"  Similarly, '..origin'
+is a shorthand for 'HEAD..origin' and asks "What did the origin do since
+I forked from them?"  Note that '..' would mean 'HEAD..HEAD' which is an
+empty range that is both reachable and unreachable from HEAD.
+
 Two other shorthands for naming a set that is formed by a commit
 and its parent commits exist.  The 'r1{caret}@' notation means all
 parents of 'r1'.  'r1{caret}!' includes commit 'r1' but excludes

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index 13495b88f5da1efc2094c0e69abfe93605ee8c03..47b4e7adb956517c22edc580892d63a99d9f219a 100644 (file)
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -224,6 +224,7 @@ static int try_difference(const char *arg)
        const char *next;
        const char *this;
        int symmetric;
+       static const char head_by_default[] = "HEAD";
 
        if (!(dotdot = strstr(arg, "..")))
                return 0;
@@ -235,9 +236,20 @@ static int try_difference(const char *arg)
        next += symmetric;
 
        if (!*next)
-               next = "HEAD";
+               next = head_by_default;
        if (dotdot == arg)
-               this = "HEAD";
+               this = head_by_default;
+
+       if (this == head_by_default && next == head_by_default &&
+           !symmetric) {
+               /*
+                * Just ".."?  That is not a range but the
+                * pathspec for the parent directory.
+                */
+               *dotdot = '.';
+               return 0;
+       }
+
        if (!get_sha1(this, sha1) && !get_sha1(next, end)) {
                show_rev(NORMAL, end, next);
                show_rev(symmetric ? NORMAL : REVERSED, sha1, this);

diff --git a/revision.c b/revision.c
index 5b81a92e3ac65ab0295f25198511fc83b4bbf1c9..457868d647378e4b3249f7c3ecae6697bc1ddc04 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -1132,15 +1132,27 @@ int handle_revision_arg(const char *arg_, struct rev_info *revs,
                const char *this = arg;
                int symmetric = *next == '.';
                unsigned int flags_exclude = flags ^ UNINTERESTING;
+               static const char head_by_default[] = "HEAD";
                unsigned int a_flags;
 
                *dotdot = 0;
                next += symmetric;
 
                if (!*next)
-                       next = "HEAD";
+                       next = head_by_default;
                if (dotdot == arg)
-                       this = "HEAD";
+                       this = head_by_default;
+               if (this == head_by_default && next == head_by_default &&
+                   !symmetric) {
+                       /*
+                        * Just ".."?  That is not a range but the
+                        * pathspec for the parent directory.
+                        */
+                       if (!cant_be_filename) {
+                               *dotdot = '.';
+                               return -1;
+                       }
+               }
                if (!get_sha1(this, from_sha1) &&
                    !get_sha1(next, sha1)) {
                        struct commit *a, *b;

diff --git a/t/t1506-rev-parse-diagnosis.sh b/t/t1506-rev-parse-diagnosis.sh
index c5cb77a0e1f34ac46dd8727341948389624e8f38..f950c101287c2f05bbd70c1faffbcf2cda1edbee 100755 (executable)
--- a/t/t1506-rev-parse-diagnosis.sh
+++ b/t/t1506-rev-parse-diagnosis.sh
@@ -182,4 +182,18 @@ test_expect_success '<commit>:file correctly diagnosed after a pathname' '
        test_cmp expect actual
 '
 
+test_expect_success 'dotdot is not an empty set' '
+       ( H=$(git rev-parse HEAD) && echo $H && echo ^$H ) >expect &&
+
+       git rev-parse HEAD.. >actual &&
+       test_cmp expect actual &&
+
+       git rev-parse ..HEAD >actual &&
+       test_cmp expect actual &&
+
+       echo .. >expect &&
+       git rev-parse .. >actual &&
+       test_cmp expect actual
+'
+
 test_done

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 71be59d446f773c4b567f00c469ac26225d11cb8..45058cc8cbe038edfb7bb953d9e10067eb5dc4b6 100755 (executable)
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -806,4 +806,11 @@ test_expect_success 'log --graph with diff and stats' '
        test_cmp expect actual.sanitized
 '
 
+test_expect_success 'dotdot is a parent directory' '
+       mkdir -p a/b &&
+       ( echo sixth && echo fifth ) >expect &&
+       ( cd a/b && git log --format=%s .. ) >actual &&
+       test_cmp expect actual
+'
+
 test_done