refspec: treat 'fetch' as a Boolean value

Since 6d4c057859 (refspec: introduce struct refspec, 2018-05-16), we
have macros called REFSPEC_FETCH and REFSPEC_PUSH. This confusingly
suggests that we might introduce other modes in the future, which, while
possible, is highly unlikely.

But these values are treated as a Boolean, and stored in a struct field
called 'fetch'. So the following:

    if (refspec->fetch == REFSPEC_FETCH) { ... }

, and

    if (refspec->fetch) { ... }

are equivalent. Let's avoid renaming the Boolean values "true" and
"false" here and remove the two REFSPEC_ macros mentioned above.

Since this value is truly a Boolean and will only ever take on a value
of 0 or 1, we can declare it as a single bit unsigned field. In
practice this won't shrink the size of 'struct refspec', but it more
clearly indicates the intent.

Note that this introduces some awkwardness like:

    refspec_item_init_or_die(&spec, refspec, 1);

, where it's unclear what the final "1" does. This will be addressed in
the following commits.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pull.c

@@ -738,7 +738,7 @@ static const char *get_tracking_branch(const char *remote, const char *refspec)
 	const char *spec_src;
 	const char *merge_branch;
 
-	refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
+	refspec_item_init_or_die(&spec, refspec, 1);
 	spec_src = spec.src;
 	if (!*spec_src || !strcmp(spec_src, "HEAD"))
 		spec_src = "HEAD";

refspec.c

@@ -233,7 +233,7 @@ void refspec_clear(struct refspec *rs)
 int valid_fetch_refspec(const char *fetch_refspec_str)
 {
 	struct refspec_item refspec;
-	int ret = refspec_item_init(&refspec, fetch_refspec_str, REFSPEC_FETCH);
+	int ret = refspec_item_init(&refspec, fetch_refspec_str, 1);
 	refspec_item_clear(&refspec);
 	return ret;
 }
@@ -249,7 +249,7 @@ void refspec_ref_prefixes(const struct refspec *rs,
 		if (item->negative)
 			continue;
 
-		if (rs->fetch == REFSPEC_FETCH) {
+		if (rs->fetch) {
 			if (item->exact_sha1)
 				continue;
 			prefix = item->src;

refspec.h

@@ -32,11 +32,8 @@ struct refspec_item {
 
 struct string_list;
 
-#define REFSPEC_FETCH 1
-#define REFSPEC_PUSH 0
-
-#define REFSPEC_INIT_FETCH { .fetch = REFSPEC_FETCH }
-#define REFSPEC_INIT_PUSH { .fetch = REFSPEC_PUSH }
+#define REFSPEC_INIT_FETCH { .fetch = 1 }
+#define REFSPEC_INIT_PUSH { .fetch = 0 }
 
 /**
  * An array of strings can be parsed into a struct refspec using
@@ -47,7 +44,7 @@ struct refspec {
 	int alloc;
 	int nr;
 
-	int fetch;
+	unsigned fetch : 1;
 };
 
 int refspec_item_init(struct refspec_item *item, const char *refspec,

remote.c

@@ -143,8 +143,8 @@ static struct remote *make_remote(struct remote_state *remote_state,
 	ret->prune = -1;  /* unspecified */
 	ret->prune_tags = -1;  /* unspecified */
 	ret->name = xstrndup(name, len);
-	refspec_init(&ret->push, REFSPEC_PUSH);
-	refspec_init(&ret->fetch, REFSPEC_FETCH);
+	refspec_init(&ret->push, 0);
+	refspec_init(&ret->fetch, 1);
 	string_list_init_dup(&ret->server_options);
 
 	ALLOC_GROW(remote_state->remotes, remote_state->remotes_nr + 1,

transport-helper.c

@@ -162,7 +162,7 @@ static struct child_process *get_helper(struct transport *transport)
 
 	data->helper = helper;
 	data->no_disconnect_req = 0;
-	refspec_init(&data->rs, REFSPEC_FETCH);
+	refspec_init(&data->rs, 1);
 
 	/*
 	 * Open the output as FILE* so strbuf_getline_*() family of