pgsql: SQL/JSON: Always coerce JsonExpr result at runtime

SQL/JSON: Always coerce JsonExpr result at runtime

Instead of looking up casts at parse time for converting the result
of JsonPath* query functions to the specified or the default
RETURNING type, always perform the conversion at runtime using either
the target type's input function or the function
json_populate_type().

There are two motivations for this change:

1. json_populate_type() coerces to types with typmod such that any
   string values that exceed length limit cause an error instead of
   silent truncation, which is necessary to be standard-conforming.

2. It was possible to end up with a cast expression that doesn't
   support soft handling of errors causing bugs in the of handling
   ON ERROR clause.

JsonExpr.coercion_expr which would store the cast expression is no
longer necessary, so remove.

Bump catversion because stored rules change because of the above
removal.

Reported-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: Discussion: https://postgr.es/m/202405271326.5a5rprki64aw%40alvherre.pgsql

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/716bd12d22c53d1943d41309f2dd061ec601dd5e

Modified Files
--------------
src/backend/executor/execExpr.c                  |  52 ++-----
src/backend/executor/execExprInterp.c            |  51 +++---
src/backend/jit/llvm/llvmjit_expr.c              |   2 +-
src/backend/nodes/nodeFuncs.c                    |  13 +-
src/backend/parser/parse_expr.c                  | 188 +++++------------------
src/backend/utils/adt/jsonfuncs.c                |  48 ++++--
src/include/catalog/catversion.h                 |   2 +-
src/include/executor/execExpr.h                  |   1 +
src/include/nodes/execnodes.h                    |   5 +-
src/include/nodes/primnodes.h                    |   8 +-
src/include/utils/jsonfuncs.h                    |   1 +
src/test/regress/expected/sqljson_jsontable.out  |  52 +++----
src/test/regress/expected/sqljson_queryfuncs.out |  72 ++++++---
src/test/regress/sql/sqljson_jsontable.sql       |   2 +-
src/test/regress/sql/sqljson_queryfuncs.sql      |  25 ++-
15 files changed, 213 insertions(+), 309 deletions(-)