re PR c++/69922 (Bogus -Wnonnull-compare for: ... ? static_cast<T*>(this) : nullptr)

re PR c++/69922 (Bogus -Wnonnull-compare for: ... ? static_cast<T*>(this) : nullptr)

	PR c++/69922
	* class.c (build_base_path): Set TREE_NO_WARNING on the null_test.
	Avoid folding it.
	* init.c (build_vec_delete_1, build_delete): Don't fold the non-NULL
	tests.
	* cp-gimplify.c (cp_fold): For TREE_NO_WARNING comparisons with NULL,
	unless they are folded into INTEGER_CST, error_mark_node or some
	comparison with NULL, avoid folding them and use either the original
	comparison or non-folded comparison of folded arguments.
	* cp-ubsan.c (cp_ubsan_instrument_vptr): Set TREE_NO_WARNING on the
	comparison, don't fold the comparison right away.

	* g++.dg/warn/Wnonnull-compare-6.C: New test.
	* g++.dg/warn/Wnonnull-compare-7.C: New test.
	* g++.dg/ubsan/pr69922.C: New test.

From-SVN: r233684