parse-options.c: make OPTION_COUNTUP respect "unspecified" values

OPT_COUNTUP() merely increments the counter upon --option, and resets it
to 0 upon --no-option, which means that there is no "unspecified" value
with which a client can initialize the counter to determine whether or
not --[no]-option was seen at all.

Make OPT_COUNTUP() treat any negative number as an "unspecified" value
to address this shortcoming. In particular, if a client initializes the
counter to -1, then if it is still -1 after parse_options(), then
neither --option nor --no-option was seen; if it is 0, then --no-option
was seen last, and if it is 1 or greater, than --option was seen last.

This change does not affect the behavior of existing clients because
they all use the initial value of 0 (or more).

Note that builtin/clean.c initializes the variable used with
OPT__FORCE (which uses OPT_COUNTUP()) to a negative value, but it is set
to either 0 or 1 by reading the configuration before the code calls
parse_options(), i.e. as far as parse_options() is concerned, the
initial value of the variable is not negative.

To test this behavior, in test-parse-options.c, "verbose" is set to
"unspecified" while quiet is set to 0 which will test the new behavior
with all sets of values.

Helped-by: Jeff King <peff@peff.net>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/test-parse-options.c b/test-parse-options.c
index 86afa9887c..f02c275f33 100644
--- a/test-parse-options.c
+++ b/test-parse-options.c
@@ -7,7 +7,8 @@ static int integer = 0;
 static unsigned long magnitude = 0;
 static unsigned long timestamp;
 static int abbrev = 7;
-static int verbose = 0, dry_run = 0, quiet = 0;
+static int verbose = -1; /* unspecified */
+static int dry_run = 0, quiet = 0;
 static char *string = NULL;
 static char *file = NULL;
 static int ambiguous;