Fix Assert failure in XMLTABLE parserHEADmaster

In an XMLTABLE expression, columns can be marked NOT NULL, and the
parser internally fabricates an option named "is_not_null" to
represent this.  However, the parser also allows users to specify
arbitrary option names.  This creates a conflict: a user can
explicitly use "is_not_null" as an option name and assign it a
non-Boolean value, which violates internal assumptions and triggers an
assertion failure.

To fix, this patch checks whether a user-supplied name collides with
the internally reserved option name and raises an error if so.
Additionally, the internal name is renamed to "__pg__is_not_null" to
further reduce the risk of collision with user-defined names.

Reported-by: Евгений Горбанев <[email protected]>
Author: Richard Guo <[email protected]>
Reviewed-by: Alvaro Herrera <[email protected]>
Discussion: https://postgr.es/m/[email protected]
Backpatch-through: 15

0 files changed, 0 insertions, 0 deletions