Hello! I'm trying to modify `regexp.c` extension for my application. So I added 3-args `regexp(re, text, noCase)` function.
I'm noticed, that queries like
> select regexp('abc', 'ABC', 1);
> select regexp('ABC', 'ABC', 1)
doesn't match.
But `select regexp('ABC', 'abc', 1)` matches.
I found out that it is because of the prefix optimiation in re_compile in lines [668-691](https://www.sqlite.org/cgi/src/file?ci=trunk&name=ext/misc/regexp.c&ln=668-692). We can see that the prefix stored as is (no case modification).
Then in re_match at line [212](https://www.sqlite.org/cgi/src/file?ci=trunk&name=ext/misc/regexp.c&ln=217) the prefix is compared case-sensitive.
The simplest way to fix it - disable prefix optimization in noCase mode - modify line [676](https://www.sqlite.org/cgi/src/file?ci=trunk&name=ext/misc/regexp.c&ln=676) from
> if( pRe->aOp[0]==RE_OP_ANYSTAR ){
to
> if( !noCase && pRe->aOp[0]==RE_OP_ANYSTAR ){
____