2018-05-31  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* sem_util.ads, sem_util.adb (Find_Primitive_Eq): New subprogram.
	* exp_ch4.adb (Expand_Composite_Equality): Use the new subprogram
	Find_Primitive_Eq to search for the primitive of types whose underlying
	type is a tagged type.

gcc/testsuite/

	* gnat.dg/tagged1.adb, gnat.dg/tagged1.ads: New testcase.

From-SVN: r260997