**   --checkin VERSION          Show diff of all changes in VERSION
**   --command PROG             External diff program - overrides "diff-command"
**   --context|-c N             Use N lines of context
**   --diff-binary BOOL         Include binary files when using external commands
**   --exec-abs-paths           Force absolute path names with external commands.
**   --exec-rel-paths           Force relative path names with external commands.
**   --from|-r VERSION          Select VERSION as source for the diff
**   --ignore-pure-adds         Ignore all sections containing only additions.
**   --internal|-i              Use internal diff logic
**   --new-file|-N              Show complete text of added and deleted files
**   --numstat                  Show only the number of lines delete and added
**   --side-by-side|-y          Side-by-side diff
**   --strip-trailing-cr        Strip trailing CR
**   --tk                       Launch a Tcl/Tk GUI for display
**   --to VERSION               Select VERSION as target for the diff

  againstUndo = find_option("undo",0,0)!=0;
  diffFlags = diff_options();
  verboseFlag = find_option("verbose","v",0)!=0;
  if( !verboseFlag ){
    verboseFlag = find_option("new-file","N",0)!=0; /* deprecated */
  }
  if( verboseFlag ) diffFlags |= DIFF_VERBOSE;
  if( find_option("ignore-pure-adds",0,0)!=0 ) diffFlags |= DIFF_IGNORE_PADDS;
  if( againstUndo && ( zFrom!=0 || zTo!=0 || zCheckin!=0 || zBranch!=0) ){
    fossil_fatal("cannot use --undo together with --from, --to, --checkin,"
                 " or --branch");
  }
  if( zBranch ){
    if( zTo || zFrom || zCheckin ){
      fossil_fatal("cannot use --from, --to, or --checkin with --branch");