2020-10-12 02:37 AEST by Arthur Barrett - Derek Price describes a Patch to support diffing across dates within a branch. This allows commands such 
as:
cvs -q rdiff -s -r"dabranch:2006/02/15 22:28" -r"dabranch:2006/02/17 00:28" MODULE

which are otherwise broken due only to command-line parsing erroneous restrictions. Thanks to Jonathan 
Kamens who pointed out this bug in cvs originally here.
http://lists.gnu.org/archive/html/bug-cvs/2002-05/msg00487.html

diff -wru cvs-1.12.13/src/patch.c cvs-1.12.13-patched/src/patch.c
--- cvs-1.12.13/src/patch.c     2005-09-23 02:03:04.000000000 +0000
+++ cvs-1.12.13-patched/src/patch.c     2006-02-16 22:53:16.000000000 +0000
@@ -270,6 +270,7 @@
     int which;
     char *repository;
     char *where;
+       char *cp;

     TRACE ( TRACE_FUNCTION, "patch_proc ( %s, %s, %s, %d, %d, %s, %s )",
            xwhere ? xwhere : "(null)",
@@ -292,7 +293,6 @@
     /* if mfile isn't null, we need to set up to do only part of the module */
     if (mfile != NULL)
     {
-       char *cp;
        char *path;

        /* if the portion of the module is a path, put the dir part on repos */
@@ -340,16 +340,30 @@
     else
        which = W_REPOS;

+
     if (rev1 != NULL && !rev1_validated)
     {
-       tag_check_valid (rev1, argc - 1, argv + 1, local_specified, 0,
-                        repository, false);
+          //tag_check_valid (rev1, argc - 1, argv + 1, local_specified, 0, repository, false);
+       if ((cp = strchr(rev1, ':')) != NULL)
+       {
+           *cp++ = '\0';
+           date1 = Make_Date (cp);
+           if (! *rev1)
+               rev1 = NULL;
+       }
        rev1_validated = 1;
     }
+
     if (rev2 != NULL && !rev2_validated)
     {
-       tag_check_valid (rev2, argc - 1, argv + 1, local_specified, 0,
-                        repository, false);
+          //tag_check_valid (rev2, argc - 1, argv + 1, local_specified, 0, repository, false);
+       if ((cp = strchr(rev2, ':')) != NULL)
+       {
+           *cp++ = '\0';
+           date2 = Make_Date (cp);
+           if (! *rev2)
+               rev2 = NULL;
+       }
        rev2_validated = 1;
     }