PR middle-end/89091
	* fold-const.c (decode_field_reference): Return NULL_TREE if
	lang_hooks.types.type_for_size returns NULL.  Check it before
	overwriting *exp_.  Use return NULL_TREE instead of return 0.

	* gcc.dg/torture/pr89091.c: New test.

Co-Authored-By: David Malcolm <dmalcolm@redhat.com>

From-SVN: r269056