Introduce `range-diff` to compare iterations of a topic branch

This command does not do a whole lot so far, apart from showing a usage
that is oddly similar to that of `git tbdiff`. And for a good reason:
the next commits will turn `range-branch` into a full-blown replacement
for `tbdiff`.

At this point, we ignore tbdiff's color options, as they will all be
implemented later using diff_options.

Since f318d739159 (generate-cmds.sh: export all commands to
command-list.h, 2018-05-10), every new command *requires* a man page to
build right away, so let's also add a blank man page, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/builtin/range-diff.c b/builtin/range-diff.c
new file mode 100644
index 00000000000..36788ea4f2b
--- /dev/null
+++ b/builtin/range-diff.c
@@ -0,0 +1,25 @@
+#include "cache.h"
+#include "builtin.h"
+#include "parse-options.h"
+
+static const char * const builtin_range_diff_usage[] = {
+N_("git range-diff [<options>] <old-base>..<old-tip> <new-base>..<new-tip>"),
+N_("git range-diff [<options>] <old-tip>...<new-tip>"),
+N_("git range-diff [<options>] <base> <old-tip> <new-tip>"),
+NULL
+};
+
+int cmd_range_diff(int argc, const char **argv, const char *prefix)
+{
+	int creation_factor = 60;
+	struct option options[] = {
+		OPT_INTEGER(0, "creation-factor", &creation_factor,
+			    N_("Percentage by which creation is weighted")),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, NULL, options,
+			     builtin_range_diff_usage, 0);
+
+	return 0;
+}