Correct handling of indices into arrays with elements larger than 1 (PR c++/96511)

Resolves:
PR c++/96511 - Incorrect -Wplacement-new on POINTER_PLUS into an array with 4-byte elements
PR middle-end/96384 - bogus -Wstringop-overflow= storing into multidimensional array with index in range

gcc/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* builtins.c (get_range): Return full range of type when neither
	value nor its range is available.  Fail for ranges inverted due
	to the signedness of offsets.
	(compute_objsize): Handle more special array members.  Handle
	POINTER_PLUS_EXPR and VIEW_CONVERT_EXPR that come up in front end
	code.
	(access_ref::offset_bounded): Define new member function.
	* builtins.h (access_ref::eval): New data member.
	(access_ref::offset_bounded): New member function.
	(access_ref::offset_zero): New member function.
	(compute_objsize): Declare a new overload.
	* gimple-array-bounds.cc (array_bounds_checker::check_array_ref): Use
	enum special_array_member.
	* tree.c (component_ref_size): Use special_array_member.
	* tree.h (special_array_member): Define a new type.
	(component_ref_size): Change signature.

gcc/cp/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* init.c (warn_placement_new_too_small): Call builtin_objsize instead
	of duplicating what it does.

gcc/testsuite/ChangeLog:

	PR c++/96511
	PR middle-end/96384
	* g++.dg/init/strlen.C: Add expected warning.
	* g++.dg/warn/Wplacement-new-size-1.C: Relax warnings.
	* g++.dg/warn/Wplacement-new-size-2.C: Same.
	* g++.dg/warn/Wplacement-new-size-6.C: Same.
	* gcc.dg/Warray-bounds-58.c: Adjust
	* gcc.dg/Wstringop-overflow-37.c: Same.
	* g++.dg/warn/Wplacement-new-size-7.C: New test.

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index c0a027a..f43ac9f 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -5292,12 +5292,22 @@ extern bool array_at_struct_end_p (tree);
    by EXP.  This does not include any offset in DECL_FIELD_BIT_OFFSET.  */
 extern tree component_ref_field_offset (tree);
 
+/* Describes a "special" array member due to which component_ref_size
+   returns null.  */
+enum struct special_array_member
+  {
+   none,      /* Not a special array member.  */
+   int_0,     /* Interior array member with size zero.  */
+   trail_0,   /* Trailing array member with size zero.  */
+   trail_1    /* Trailing array member with one element.  */
+  };
+
 /* Return the size of the member referenced by the COMPONENT_REF, using
    its initializer expression if necessary in order to determine the size
    of an initialized flexible array member.  The size might be zero for
    an object with an uninitialized flexible array member or null if it
    cannot be determined.  */
-extern tree component_ref_size (tree, bool * = NULL);
+extern tree component_ref_size (tree, special_array_member * = NULL);
 
 extern int tree_map_base_eq (const void *, const void *);
 extern unsigned int tree_map_base_hash (const void *);