ICU-23179 Test more edge cases when mapping syntax characters to sets

[eggrobin]

As for ^, - is treated normally at the beginning of a UnicodeSet and as a set elsewhere.

Again, this is madness and we should probably get rid of this possibility, but for now let us make sure we know exactly which way madness lies.

Checklist

• Required: Issue filed: ICU-23179
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-1234 Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

[eggrobin]

@markusicu, friendly ping (#3604, the UnicodeSet parser rewrite, is waiting behind this one).

[macchiati]

As for ^, - is treated normally at the beginning of a UnicodeSet and as a set elsewhere.

I didn't understand "as a set elsewhere". Did you mean is treated as syntax to form a range elsewhere? Eg [a-b]?
BTW I think we only had the "is normal at the start" to match regexes.

[eggrobin]

I didn't understand "as a set elsewhere". Did you mean is treated as syntax to form a range elsewhere? Eg [a-b]?

The context here is that the symbol table can map characters to sets, e.g., it can say “0 means [a-z]”. And this can be done to syntax characters, e.g., “- means [1-9]”. The effect of mapping syntax characters varies, and this is what this pull request tests. Obviously this is madness and we should disallow the mapping of syntax characters in a future version of ICU, but for now I am testing exactly what madness happens so I can preserve it in my rewrite of the parser.

[macchiati]

Got it, thanks!

…

On Thu, Sep 11, 2025, 06:04 Robin Leroy ***@***.***> wrote: *eggrobin* left a comment (unicode-org/icu#3612) <#3612 (comment)> I didn't understand "as a set elsewhere". Did you mean is treated as syntax to form a range elsewhere? Eg [a-b]? The context here is that the symbol table can map characters to sets, e.g., it can say “0 means [a-z]”. And this can be done to syntax characters, e.g., “- means [1-9]”. The effect of mapping syntax characters varies, and this is what this pull request tests. Obviously this is madness and we should disallow the mapping of syntax characters in a future version of ICU, but for now I am testing exactly what madness happens so I can preserve it in my rewrite of the parser. — Reply to this email directly, view it on GitHub <#3612 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACJLEMDZCW67MM574HPHZKT3SFXOBAVCNFSM6AAAAACE6CVYGWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTEOBQGU2TGOBYGE> . You are receiving this because you commented.Message ID: ***@***.***>