pgsql: Deparse FOR PORTION OF using the range column's current name.

Deparse FOR PORTION OF using the range column's current name.

Commit 8e72d914c recorded the range column's name in ForPortionOfExpr
and used that for deparsing FOR PORTION OF. This gives the wrong
answer if the ForPortionOfExpr is saved in a rule or SQL function and
then the column gets renamed. Drop the ForPortionOfExpr.range_name
field; instead fetch the current column name from the catalogs when
needed.

Also drop ForPortionOfState.fp_rangeName, which wasn't being used
anywhere.

Full disclosure: an earlier draft of this patch was made with
Claude Opus 4.8.

Reported-by: John Naylor <johncnaylorls(at)gmail(dot)com>
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Richard Guo <guofenglinux(at)gmail(dot)com>
Reviewed-by: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
Discussion: https://postgr.es/m/CANWCAZYFEpJ5Oi45gi4q9Y6LYa4_oiAXxuNNWe-1ym-i0fF8Pw@mail.gmail.com
Backpatch-through: 19

Branch
------
REL_19_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/2a9541ddfd3a5b069c505e36a91f289126871a21

Modified Files
--------------
src/backend/executor/nodeModifyTable.c | 2 --
src/backend/optimizer/plan/planner.c | 4 +++-
src/backend/parser/analyze.c | 1 -
src/backend/utils/adt/ruleutils.c | 15 +++++++++----
src/include/catalog/catversion.h | 2 +-
src/include/nodes/execnodes.h | 1 -
src/include/nodes/primnodes.h | 1 -
src/test/regress/expected/for_portion_of.out | 33 ++++++++++++++++++++++++++++
src/test/regress/sql/for_portion_of.sql | 16 ++++++++++++++
9 files changed, 64 insertions(+), 11 deletions(-)