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(cvs.info)Conflicts example

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Conflicts example
=================

   Suppose revision 1.4 of `driver.c' contains this:

     #include <stdio.h>
     
     void main()
     {
         parse();
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? 0 : 1);
     }

Revision 1.6 of `driver.c' contains this:

     #include <stdio.h>
     
     int main(int argc,
              char **argv)
     {
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(!!nerr);
     }

Your working copy of `driver.c', based on revision 1.4, contains this
before you run `cvs update':

     #include <stdlib.h>
     #include <stdio.h>
     
     void main()
     {
         init_scanner();
         parse();
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
     }

You run `cvs update':

     $ cvs update driver.c
     RCS file: /usr/local/cvsroot/yoyodyne/tc/driver.c,v
     retrieving revision 1.4
     retrieving revision 1.6
     Merging differences between 1.4 and 1.6 into driver.c
     rcsmerge warning: overlaps during merge
     cvs update: conflicts found in driver.c
     C driver.c

CVS tells you that there were some conflicts.  Your original working
file is saved unmodified in `.#driver.c.1.4'.  The new version of
`driver.c' contains this:

     #include <stdlib.h>
     #include <stdio.h>
     
     int main(int argc,
              char **argv)
     {
         init_scanner();
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
     <<<<<<< driver.c
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
     =======
         exit(!!nerr);
     >>>>>>> 1.6
     }

Note how all non-overlapping modifications are incorporated in your
working copy, and that the overlapping section is clearly marked with
`<<<<<<<', `=======' and `>>>>>>>'.

   You resolve the conflict by editing the file, removing the markers
and the erroneous line.  Suppose you end up with this file:
     #include <stdlib.h>
     #include <stdio.h>
     
     int main(int argc,
              char **argv)
     {
         init_scanner();
         parse();
         if (argc != 1)
         {
             fprintf(stderr, "tc: No args expected.\n");
             exit(1);
         }
         if (nerr == 0)
             gencode();
         else
             fprintf(stderr, "No code generated.\n");
         exit(nerr == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
     }

You can now go ahead and commit this as revision 1.7.

     $ cvs commit -m "Initialize scanner. Use symbolic exit values." driver.c
     Checking in driver.c;
     /usr/local/cvsroot/yoyodyne/tc/driver.c,v  <--  driver.c
     new revision: 1.7; previous revision: 1.6
     done

   For your protection, CVS will refuse to check in a file if a
conflict occurred and you have not resolved the conflict.  Currently to
resolve a conflict, you must change the timestamp on the file.  In
previous versions of CVS, you also needed to insure that the file
contains no conflict markers.  Because your file may legitimately
contain conflict markers (that is, occurrences of `>>>>>>> ' at the
start of a line that don't mark a conflict), the current version of CVS
will print a warning and proceed to check in the file.

   If you use release 1.04 or later of pcl-cvs (a GNU Emacs front-end
for CVS) you can use an Emacs package called emerge to help you resolve
conflicts.  See the documentation for pcl-cvs.