Re: [HACKERS] GSoC 2017: Foreign Key Arrays

+       if (ARR_NDIM(arr) != 1 ||
+           ARR_HASNULL(arr) ||
+           ARR_ELEMTYPE(arr) != CHAROID)
+           elog(ERROR, "confreftype is not a 1-D char array");

I think the ARR_HASNULL(arr) condition is not reflected in the error message.

+    * Array foreign keys support only UPDATE/DELETE NO ACTION, UPDATE/DELETE
+    * RESTRICT amd DELETE CASCADE actions

I don't see CASCADE in the if condition that follows the above comment.

+   char        reftype;        /* FKCONSTR_REF_xxx code */

The code would be FKCONSTR_REF_EACH_ELEMENT and FKCONSTR_REF_PLAIN. I think you can mention them in the comment.

Cheers