The documentation for std.getopt includes the following example:
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bool foo, bar;
getopt(args,
std.getopt.config.caseSensitive,
"foo", &foo,
"bar", &bar);
In the example above, "--foo", "--bar", "--FOo", "--bAr" etc. are recognized. The directive is active til the end of getopt, or until the converse directive caseInsensitive is encountered:
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Presumably "recognized" was supposed to be "rejected".