2009-10-28  Richard Guenther  <rguenther@suse.de>

	PR lto/41808
	PR lto/41839
	* tree-ssa.c (useless_type_conversion_p): Do not treat
	conversions to pointers to incomplete types as useless.
	* gimple.c (gimple_types_compatible_p): Compare struct tags,
	not typedef names.

	* gcc.dg/lto/20091027-1_0.c: New testcase.
	* gcc.dg/lto/20091027-1_1.c: Likewise.
	* g++.dg/lto/20091026-1_0.C: Likewise.
	* g++.dg/lto/20091026-1_1.C: Likewise.
	* g++.dg/lto/20091026-1_a.h: Likewise.

From-SVN: r153671