PR tree-optimization/84468 - bogus -Wstringop-truncation despite assignment after conditional strncpy

gcc/ChangeLog:

	PR tree-optimization/84468
	* tree-ssa-strlen.c (maybe_diag_stxncpy_trunc): Consider successor
	basic block when looking for nul assignment.

gcc/testsuite/ChangeLog:

	PR tree-optimization/84468
	* g++.dg/warn/Wstringop-truncation-2.C: New test.
	* gcc.dg/Wstringop-truncation.c: New test.
	* gcc.dg/Wstringop-truncation-2.c: New test.

From-SVN: r258339