On Fri, 2025-09-12 at 20:12 -0400, Tom Lane wrote:
> I had not particularly studied the new charclass-parsing logic.
> Looking at it now, this bit further down (lines 871ff) looks
> fishy:
>
> if (pchar == ']' && charclass_start > 2)
> charclass_depth--;
> else if (pchar == '[')
> charclass_depth++;
>
> /*
> * If there is a caret right after the opening bracket, it negates
> * the character class, but a following closing bracket should
> * still be treated as a normal character. That holds only for
> * the first caret, so only the values 1 and 2 mean that closing
> * brackets should be taken literally.
> */
> if (pchar == '^')
> charclass_start++;
> else
> charclass_start = 3; /* definitely past the start */
>
> Should not we be setting charclass_start to 1 after incrementing
> charclass_depth?
What I call "charclass depth" is misleading, I am afraid.
Really, it should be "bracket depth". Only the outermost pair of brackets
starts an actual character class. Example:
[]abc[:digit:]]
A caret or closing bracket right after the inner opening bracket wouldn't
be a special character, and I think it would never be legal.
Unfortunately, this is all pretty complicated.
Perhaps s/charclass_depth/bracket_depth/ would be a good idea.
Yours,
Laurenz Albe
