re PR c/81233 (--Wdiscarded-qualifiers and Wincompatible-pointer-types missing important detail)

	PR c/81233
	* c-typeck.c (pedwarn_init): Make the function take a variable list.
	Call emit_diagnostic_valist instead of pedwarn.
	(convert_for_assignment): Unroll the PEDWARN_FOR_ASSIGNMENT macro.
	Print the relevant types in diagnostics.

	* diagnostic-core.h (emit_diagnostic_valist): Add declaration.
	* diagnostic.c (emit_diagnostic): Add a comment.
	(emit_diagnostic_valist): New function.

	* gcc.dg/diagnostic-types-1.c: New test.
	* gcc.dg/assign-warn-1.c: Update warning messages.
	* gcc.dg/assign-warn-2.c: Likewise.
	* gcc.dg/c90-const-expr-5.c: Likewise.
	* gcc.dg/c99-const-expr-5.c: Likewise.
	* gcc.dg/conv-2.c: Likewise.
	* gcc.dg/init-bad-7.c: Likewise.
	* gcc.dg/overflow-warn-1.c: Likewise.
	* gcc.dg/overflow-warn-2.c: Likewise.
	* gcc.dg/overflow-warn-3.c: Likewise.
	* gcc.dg/overflow-warn-4.c: Likewise.
	* gcc.dg/pointer-array-atomic.c: Likewise.
	* gcc.dg/pr26865.c: Likewise.
	* gcc.dg/pr61162-2.c: Likewise.
	* gcc.dg/pr61162.c: Likewise.
	* gcc.dg/pr67730-2.c: Likewise.
	* gcc.dg/pr69156.c: Likewise.
	* gcc.dg/pr70174.c: Likewise.
	* objc.dg/proto-lossage-4.m: Likewise.

From-SVN: r250985