Empty LineString created with HasZ() is true #993
Description
I am trying to track down an issue in recent versions of GeoDjango where empty LineString objects are being created with the hasz property True. The following code is outputting True with libgeos version 3.12.0_CAPI_1.18.0. When run with 3.11.2-CAPI-1.17.2 the code putputs False
from django.contrib.gis.geos import LineString, geos_version
print(geos_version())
ls = LineString()
print(ls.hasz)I have traced this down to the C libgeos API where GEOSGeom_createLineString is getting called with a NULL argument.
Following is a short C program that demonstrates this. When run with version 3.12.0 of libgeos it outputs GEOSHasZ() = 1. With version 3.11.0 it outputs GEOSHasZ() = 0.
#include <stdio.h>
#include <stdarg.h>
#include <geos_c.h>
static void geos_msg_handler(const char* fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vprintf (fmt, ap);
va_end(ap);
}
int main()
{
/* Send notice and error messages to the terminal */
initGEOS(geos_msg_handler, geos_msg_handler);
printf("GEOS Version %s\n", GEOSversion());
GEOSGeometry* geom = GEOSGeom_createLineString(NULL);
GEOSWKTWriter* writer = GEOSWKTWriter_create();
char* wkt = GEOSWKTWriter_write(writer, geom);
printf("Geometry: %s\n", wkt);
printf("GEOSHasZ() = %d\n", GEOSHasZ(geom));
/* Clean up allocated objects */
GEOSWKTWriter_destroy( writer);
GEOSGeom_destroy(geom);
/* Clean up the global context */
finishGEOS();
return 0;
}