PR c/53562 - Add -Werror= support for -D_FORTIFY_SOURCE / __builtin___memcpy_chk
PR middle-end/77784 - duplicate warning for snprintf when n > object size
PR middle-end/78149 - missing warning on strncpy buffer overflow due to an excessive bound
PR middle-end/78138 - missing warnings on buffer overflow with non-constant source length

gcc/c-family/ChangeLog:

	PR c/53562
	PR middle-end/77784
	PR middle-end/78149
	PR middle-end/78138
	* c.opt (-Wstringop-overflow): New option.

gcc/ChangeLog:

	PR middle-end/77784
	PR middle-end/78149
	PR middle-end/78138
	
	* builtins.c (expand_builtin_strcat, expand_builtin_strncat): New
	functions.
	(compute_dest_size, get_size_range, check_sizes, check_strncat_sizes)
	(check_memop_sizes): Same.
	(expand_builtin_memcpy): Call check memop_sizes.
	(expand_builtin_mempcpy): Same.
	(expand_builtin_memset): Same,
	(expand_builtin_bzero): Same.
	(expand_builtin_memory_chk): Call check_sizes.
	(expand_builtin_strcpy): Same.
	(expand_builtin_strncpy): Same.
	(maybe_emit_sprintf_chk_warning): Same.
	(expand_builtin): Handle strcat and strncat.
	(fini_object_sizes): Reset pointers.
	(compute_object_size): New function.
	* gimple-ssa-sprintf.c (pass_sprintf_length::handle_gimple_call):
	Avoid issuing warnings also issued during built-in expansion.
	* doc/invoke.texi (Warning Options): Document -Wstringop-overflow.

gcc/testsuite/ChangeLog:

	PR middle-end/77784
	PR middle-end/78149
	PR middle-end/78138

	* c-c++-common/Wsizeof-pointer-memaccess2.c: Adjust expected diagnostic.
	* g++.dg/ext/builtin-object-size3.C (bar): Same.
	* g++.dg/ext/strncpy-chk1.C: Same.
	* g++.dg/opt/memcpy1.C: Same.
	* g++.dg/torture/Wsizeof-pointer-memaccess1.C: Same.
	* gcc.c-torture/compile/pr55569.c: Disable -Wstringop-overflow.
	* gcc.dg/Wobjsize-1.c: Adjust expected diagnostic.
	* gcc.dg/attr-alloc_size.c: Same.
	* gcc.dg/builtin-stringop-chk-1.c: Adjust expected diagnostic.
	* gcc.dg/builtin-stringop-chk-2.c: Same.
	* gcc.dg/builtin-stringop-chk-4.c: New test.
	* gcc.dg/builtin-strncat-chk-1.c: Adjust expected diagnostic.
	* gcc.dg/memcpy-2.c: Same.
	* gcc.dg/pr40340-1.c: Same.
	* gcc.dg/pr40340-2.c (main): Same.
	* gcc.dg/pr40340-5.c (main): Same.
	* gcc.dg/torture/Wsizeof-pointer-memaccess1.c: Same.
	* gcc.dg/torture/pr71132.c: Disable -Wstringop-overflow.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-1.c: Adjust text of expected
	warning.
	* gfortran.dg/char_length_3.f90: Prune expected warnings.
	* gfortran.dg/pr38868.f: Add expected warnings.

From-SVN: r243419