Re: some git confusion (where git's advice didn't help)

[Duy Nguyen <pclouds@gmail.com>]

On Tue, May 14, 2019 at 07:21:15AM -0400, Jeff King wrote:
> I also think the "warning: refname ... is ambiguous" message would
> probably be a bit more helpful if it showed _which_ candidates it found
> (and which one it chose!).

Alternatively, just refuse to resolve ambiguous refs. It's not always
printed in a short output that stands out to you. Something like this
perhaps.

It could probably use some improvements, suggesting the ambiguous
candidates too. It's just what I've been using for years.

-- 8< --
Subject: [PATCH] sha1_name.c: add an option to abort on ambiguous refs

There are cases when a warning on ambiguous ref may go unnoticed
(e.g. git-log filling up the whole screen). There are also cases when
people want to catch ambiguation early (e.g. it happens deep in some
script). In either case, aborting the program would accomplish it.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/config/core.txt |  3 ++-
 config.c                      |  5 ++++-
 sha1-name.c                   | 10 ++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt
index 7e9b6c8f4c..f81634b642 100644
--- a/Documentation/config/core.txt
+++ b/Documentation/config/core.txt
@@ -340,7 +340,8 @@ core.sharedRepository::
 
 core.warnAmbiguousRefs::
 	If true, Git will warn you if the ref name you passed it is ambiguous
-	and might match multiple refs in the repository. True by default.
+	and might match multiple refs in the repository. If set to "fatal",
+	the program will abort on ambiguous refs. True by default.
 
 core.compression::
 	An integer -1..9, indicating a default compression level.
diff --git a/config.c b/config.c
index 0f0cdd8c0f..f314caeb87 100644
--- a/config.c
+++ b/config.c
@@ -1158,7 +1158,10 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
 	}
 
 	if (!strcmp(var, "core.warnambiguousrefs")) {
-		warn_ambiguous_refs = git_config_bool(var, value);
+		if (!strcasecmp(value, "fatal"))
+			warn_ambiguous_refs = 2;
+		else
+			warn_ambiguous_refs = git_config_bool(var, value);
 		return 0;
 	}
 
diff --git a/sha1-name.c b/sha1-name.c
index 6dda2c16df..e613c955d7 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -760,6 +760,8 @@ static int get_oid_basic(const char *str, int len, struct object_id *oid,
 				warning(warn_msg, len, str);
 				if (advice_object_name_warning)
 					fprintf(stderr, "%s\n", _(object_name_msg));
+				if (warn_ambiguous_refs > 1)
+					die(_("cannot continue with ambiguous refs"));
 			}
 			free(real_ref);
 		}
@@ -817,8 +819,12 @@ static int get_oid_basic(const char *str, int len, struct object_id *oid,
 
 	if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 	    (refs_found > 1 ||
-	     !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
-		warning(warn_msg, len, str);
+	     !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY))) {
+		if (warn_ambiguous_refs > 1)
+			die(warn_msg, len, str);
+		else
+			warning(warn_msg, len, str);
+	}
 
 	if (reflog_len) {
 		int nth, i;
-- 
2.21.0.1141.gd54ac2cb17

-- 8< --