re PR tree-optimization/69483 (gcc ICE on x86_64-linux-gnu with "expected class 'type', have 'exceptional' (error_mark) in useless_type_conversion_p")

	PR tree-optimization/69483
	* gimple-fold.c (canonicalize_constructor_val): Return NULL
	if base has error_mark_node type.

	* c-parser.c (c_parser_translation_unit): Use FOR_EACH_VEC_ELT.

	* gcc.dg/pr69483.c: New test.
	* g++.dg/opt/pr69483.C: New test.

From-SVN: r232833