[estebanzimanyi]

A wrapper can hand the call info and the addresses of its locals to a helper reading its arguments: Raster_value_count_rows calls value_count_args(fcinfo, false, &band, &exclude_nodata, &searchvalues, &nsearch, &roundto), which sets *band = nargs >= 4 ? PG_GETARG_INT32(1) : 1 and *exclude_nodata = nargs == 5 ? PG_GETARG_BOOL(2) : true. extract_wrappers and extract_helpers read each such call as the statements the helper runs (_expand_arg_helpers): each *p and (*p) as the local whose address p receives, a bare p as that address, a parameter given a literal as the literal, the local holding PG_NARGS() as PG_NARGS(), and a value chosen by the number of arguments as the value of the other numbers followed by its replacement under that test, band = 1; if (PG_NARGS() >= 4) band = PG_GETARG_INT32(1);, the shape _guarded_default reads. A call handing the helper no address is a delegation and stays.

attach_null_default_binds follows a wrapper into the helper it delegates to, as merge_boundargs follows it, and reads a local starting from a literal and replaced only where argument k is not NULL (_notnull_default) as passing that literal for a NULL k. It reads the body for the number of arguments of each signature (_fold_nargs): PG_NARGS() as that number, a sum or difference of numbers as its value, a local set once to a number as that number where it indexes an argument, and a statement under a condition no argument changes, if (false), as one that never runs.

Witness: on master, valueCount(raster, integer, float[], float) and valueCount(raster, float[], float), and their valuePercent twins, state no boundArgs, so no binding fills the C parameters exclude_nodata and band they leave out, and valueCount(raster, integer, boolean, float[], float) states no nullDefaultBinds for searchvalues DEFAULT NULL. Here the 4-argument forms bind exclude_nodata true, the 3-argument ones band 1 and exclude_nodata true, and a NULL searchvalues passes searchvalues NULL and nsearch 0, as value_count_args reads them.

Measured over MobilityDB master f3d480c80a, from the headers of the libmeos it builds, as the tests job derives the catalog: the catalog differs from master's in raster_value_count, as above; in raster_clip, whose clip(raster, integer[], geometry, float[], boolean, boolean) passes nodata NULL and nnodata 0 for a NULL nodataval; and in raster_set_values, whose NULL noset passes noset NULL; each as its wrapper sets the local NULL and replaces it only under ! PG_ARGISNULL(k). Over that catalog the JVM generators of JMEOS main and MobilityDuck main's generator write the same files as over master's. tests/test_boundargs.py reads the binds of each number of arguments a helper leaves, the NULL default it replaces only when given, and no extra bind where every signature states every argument the helper reads; the suite passes, 602 tests and none skipped, with MDB_SRC_ROOT, MEOS_LIBRARY_PATH, MEOS_INCLUDE_DIR and PYMEOS_FACTORY set as the tests job sets them.

Why: the C parameters a SQL signature leaves out reach a binding only through the binds the catalog states; a wrapper reading them through a helper stated none, so no binding could place those signatures.