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, and must also insure that the file contains no conflict markers. If your file legitimately contains conflict markers (that is, occurrences of `>>>>>>> ' at the start of a line that don't mark a conflict), then CVS has trouble handling this and you need to start hacking on the CVS/Entries file or other such workarounds.

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.

Go to the first, previous, next, last section, table of contents.