re PR tree-optimization/86159 (g++ ICE at -O1 and above on valid code: incorrect type of vector CONSTRUCTOR elements)

2018-06-15  Richard Biener  <rguenther@suse.de>

	PR middle-end/86159
	* tree-cfg.c (gimplify_build3): Do not strip sign conversions,
	leave useless conversion stripping to force_gimple_operand_gsi.
	(gimplify_build2): Likewise.
	(gimplify_build1): Likewise.

	* g++.dg/pr86159.C: New testcase.

From-SVN: r261622