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-rw-r--r--Documentation/git-update-ref.txt18
-rw-r--r--builtin/update-ref.c2
-rwxr-xr-xt/t1400-update-ref.sh5
3 files changed, 17 insertions, 8 deletions
diff --git a/Documentation/git-update-ref.txt b/Documentation/git-update-ref.txt
index 0a0a551..c8f5ae5 100644
--- a/Documentation/git-update-ref.txt
+++ b/Documentation/git-update-ref.txt
@@ -68,7 +68,12 @@ performs all modifications together. Specify commands of the form:
option SP <opt> LF
Quote fields containing whitespace as if they were strings in C source
-code. Alternatively, use `-z` to specify commands without quoting:
+code; i.e., surrounded by double-quotes and with backslash escapes.
+Use 40 "0" characters or the empty string to specify a zero value. To
+specify a missing value, omit the value and its preceding SP entirely.
+
+Alternatively, use `-z` to specify in NUL-terminated format, without
+quoting:
update SP <ref> NUL <newvalue> NUL [<oldvalue>] NUL
create SP <ref> NUL <newvalue> NUL
@@ -76,8 +81,12 @@ code. Alternatively, use `-z` to specify commands without quoting:
verify SP <ref> NUL [<oldvalue>] NUL
option SP <opt> NUL
-Lines of any other format or a repeated <ref> produce an error.
-Command meanings are:
+In this format, use 40 "0" to specify a zero value, and use the empty
+string to specify a missing value.
+
+In either format, values can be specified in any form that Git
+recognizes as an object name. Commands in any other format or a
+repeated <ref> produce an error. Command meanings are:
update::
Set <ref> to <newvalue> after verifying <oldvalue>, if given.
@@ -102,9 +111,6 @@ option::
The only valid option is `no-deref` to avoid dereferencing
a symbolic ref.
-Use 40 "0" or the empty string to specify a zero value, except that
-with `-z` an empty <oldvalue> is considered missing.
-
If all <ref>s can be locked with matching <oldvalue>s
simultaneously, all modifications are performed. Otherwise, no
modifications are performed. Note that while each individual
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index c61120f..6f3b909 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -154,6 +154,8 @@ static int parse_next_sha1(struct strbuf *input, const char **next,
goto invalid;
} else if (flags & PARSE_SHA1_ALLOW_EMPTY) {
/* With -z, treat an empty value as all zeros: */
+ warning("%s %s: missing <newvalue>, treating as zero",
+ command, refname);
hashclr(sha1);
} else {
/*
diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
index 15f5bfd..2d61cce 100755
--- a/t/t1400-update-ref.sh
+++ b/t/t1400-update-ref.sh
@@ -730,10 +730,11 @@ test_expect_success 'stdin -z fails update with bad ref name' '
grep "fatal: invalid ref format: ~a" err
'
-test_expect_success 'stdin -z treats empty new value as zeros' '
+test_expect_success 'stdin -z emits warning with empty new value' '
git update-ref $a $m &&
printf $F "update $a" "" "" >stdin &&
- git update-ref -z --stdin <stdin &&
+ git update-ref -z --stdin <stdin 2>err &&
+ grep "warning: update $a: missing <newvalue>, treating as zero" err &&
test_must_fail git rev-parse --verify -q $a
'