handle-empty-arrays-correctly-always.patch

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index bd8a15d..09abd46 100644
*** a/src/backend/executor/execExprInterp.c
--- b/src/backend/executor/execExprInterp.c
*************** ExecEvalArrayExpr(ExprState *state, Expr
*** 2131,2144 ****
  		Datum	   *dvalues = op->d.arrayexpr.elemvalues;
  		bool	   *dnulls = op->d.arrayexpr.elemnulls;
  
- 		/* Shouldn't happen here, but if length is 0, return empty array */
- 		if (nelems == 0)
- 		{
- 			*op->resvalue =
- 				PointerGetDatum(construct_empty_array(element_type));
- 			return;
- 		}
- 
  		/* setup for 1-D array of the given length */
  		ndims = 1;
  		dims[0] = nelems;
--- 2131,2136 ----
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index e4101c9..d1f2fe7 100644
*** a/src/backend/utils/adt/arrayfuncs.c
--- b/src/backend/utils/adt/arrayfuncs.c
*************** array_map(FunctionCallInfo fcinfo, Oid r
*** 3297,3302 ****
--- 3297,3303 ----
   *
   * A palloc'd 1-D array object is constructed and returned.  Note that
   * elem values will be copied into the object even if pass-by-ref type.
+  * Also note the result will be 0-D not 1-D if nelems = 0.
   *
   * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
   * from the system catalogs, given the elmtype.  However, the caller is
*************** construct_array(Datum *elems, int nelems
*** 3331,3336 ****
--- 3332,3338 ----
   *
   * A palloc'd ndims-D array object is constructed and returned.  Note that
   * elem values will be copied into the object even if pass-by-ref type.
+  * Also note the result will be 0-D not ndims-D if any dims[i] = 0.
   *
   * NOTE: it would be cleaner to look up the elmlen/elmbval/elmalign info
   * from the system catalogs, given the elmtype.  However, the caller is
*************** construct_md_array(Datum *elems,
*** 3362,3373 ****
  				 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
  						ndims, MAXDIM)));
  
- 	/* fast track for empty array */
- 	if (ndims == 0)
- 		return construct_empty_array(elmtype);
- 
  	nelems = ArrayGetNItems(ndims, dims);
  
  	/* compute required space */
  	nbytes = 0;
  	hasnulls = false;
--- 3364,3375 ----
  				 errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
  						ndims, MAXDIM)));
  
  	nelems = ArrayGetNItems(ndims, dims);
  
+ 	/* if ndims <= 0 or any dims[i] == 0, return empty array */
+ 	if (nelems <= 0)
+ 		return construct_empty_array(elmtype);
+ 
  	/* compute required space */
  	nbytes = 0;
  	hasnulls = false;