[PATCH] sha1_name.c: add an option to abort on ambiguous refs

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

There are cases when a warning on ambiguous refs may go unnoticed
(e.g. git-log filling up the whole screen). There are also cases when
people want to catch ambiguity 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.txt |  3 ++-
 config.c                 |  5 ++++-
 sha1_name.c              | 10 ++++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2cd6bdd..4172f59 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -522,7 +522,8 @@ 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 9ba40bc..79f1ea5 100644
--- a/config.c
+++ b/config.c
@@ -738,7 +738,10 @@ static int git_default_core_config(const char *var, const char *value)
 	}
 
 	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 3acf221..a0f0ab9 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -480,6 +480,8 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 				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);
 		}
@@ -537,8 +539,12 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 
 	if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 	    (refs_found > 1 ||
-	     !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
-		warning(warn_msg, len, str);
+	     !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY))) {
+		if (warn_ambiguous_refs > 1)
+			die(warn_msg, len, str);
+		else
+			warning(warn_msg, len, str);
+	}
 
 	if (reflog_len) {
 		int nth, i;
-- 
2.8.0.rc0.210.gd302cd2