Issue 17650: std.getopt range violation when option value is a hyphen

[jondegenhardt]

This fixes an issue in std.getopt private function optMatch. This function is used to see if a command line argument represents an option (e.g. "--file", "-a", etc.). It looks at all the arguments on the command line, including option values. (In $ command -f 1 -g 2, "1" and "2" are option values.)

The range violation occurs if an option value is a single hyphen. The optMatch function sees the hyphen and assumes it might be an option argument (like "-f"). It then tests the next character in the string. When the value is a single hyphen the next character does not exist.

A single hyphen (or a single optionChar) only introduces an option, it is never an option by itself. So the easy fix is to also check that the length is at least 2.

Note: Looking through this code it appears there may be other problems like this. I've elected to fix only this case in this PR, as it is the most pressing issue.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Description
✓	17650	[REG v2.075.0 b1-b4] std.getopt range violation

[andralex]

thx!