diff: add synonyms for -M, -C, -B

Add new long-form options --detect-renames[=<n>], --detect-copies[=<n>],
and --break-rewrites[=[<n>][/<m>]] as synonyms for the -M, -C, and -B
options (respectively).

Signed-off-by: Kevin Ballard <kevin@sb.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/diff-options.txt

@@ -207,9 +207,11 @@ endif::git-format-patch[]
 	digits can be specified with `--abbrev=<n>`.
 
 -B::
+--break-rewrites[=[<n>][/<m>]]::
 	Break complete rewrite changes into pairs of delete and create.
 
 -M::
+--detect-renames[=<n>]::
 ifndef::git-log[]
 	Detect renames.
 endif::git-log[]
@@ -220,6 +222,7 @@ ifdef::git-log[]
 endif::git-log[]
 
 -C::
+--detect-copies[=<n>]::
 	Detect copies as well as renames.  See also `--find-copies-harder`.
 
 ifndef::git-format-patch[]

diff.c

@@ -3059,16 +3059,19 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 	}
 
 	/* renames options */
-	else if (!prefixcmp(arg, "-B")) {
+	else if (!prefixcmp(arg, "-B") || !prefixcmp(arg, "--break-rewrites=") ||
+		 !strcmp(arg, "--break-rewrites")) {
 		if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
 			return -1;
 	}
-	else if (!prefixcmp(arg, "-M")) {
+	else if (!prefixcmp(arg, "-M") || !prefixcmp(arg, "--detect-renames=") ||
+		 !strcmp(arg, "--detect-renames")) {
 		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
 			return -1;
 		options->detect_rename = DIFF_DETECT_RENAME;
 	}
-	else if (!prefixcmp(arg, "-C")) {
+	else if (!prefixcmp(arg, "-C") || !prefixcmp(arg, "--detect-copies=") ||
+		 !strcmp(arg, "--detect-copies")) {
 		if (options->detect_rename == DIFF_DETECT_COPY)
 			DIFF_OPT_SET(options, FIND_COPIES_HARDER);
 		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
@@ -3262,6 +3265,22 @@ static int diff_scoreopt_parse(const char *opt)
 	if (*opt++ != '-')
 		return -1;
 	cmd = *opt++;
+	if (cmd == '-') {
+		/* convert the long-form arguments into short-form versions */
+		if (!prefixcmp(opt, "break-rewrites")) {
+			opt += strlen("break-rewrites");
+			if (*opt == 0 || *opt++ == '=')
+				cmd = 'B';
+		} else if (!prefixcmp(opt, "detect-copies")) {
+			opt += strlen("detect-copies");
+			if (*opt == 0 || *opt++ == '=')
+				cmd = 'C';
+		} else if (!prefixcmp(opt, "detect-renames")) {
+			opt += strlen("detect-renames");
+			if (*opt == 0 || *opt++ == '=')
+				cmd = 'M';
+		}
+	}
 	if (cmd != 'M' && cmd != 'C' && cmd != 'B')
 		return -1; /* that is not a -M, -C nor -B option */