Implement a solution for PR middle-end/10138 and PR middle-end/95136.

PR middle-end/10138 - warn for uninitialized arrays passed as const arguments
PR middle-end/95136 - missing -Wuninitialized on an array access with a variable offset

gcc/c-family/ChangeLog:

	PR middle-end/10138
	PR middle-end/95136
	* c-attribs.c (append_access_attrs): Handle attr_access::none.
	(handle_access_attribute): Same.

gcc/ChangeLog:

	PR middle-end/10138
	PR middle-end/95136
	* attribs.c (init_attr_rdwr_indices): Move function here.
	* attribs.h (rdwr_access_hash, rdwr_map): Define.
	(attr_access): Add 'none'.
	(init_attr_rdwr_indices): Declared function.
	* builtins.c (warn_for_access)): New function.
	(check_access): Call it.
	* builtins.h (checK-access): Add an optional argument.
	* calls.c (rdwr_access_hash, rdwr_map): Move to attribs.h.
	(init_attr_rdwr_indices): Declare extern.
	(append_attrname): Handle attr_access::none.
	(maybe_warn_rdwr_sizes): Same.
	(initialize_argument_information): Update comments.
	* doc/extend.texi (attribute access): Document 'none'.
	* tree-ssa-uninit.c (struct wlimits): New.
	(maybe_warn_operand): New function.
	(maybe_warn_pass_by_reference): Same.
	(warn_uninitialized_vars): Refactor code into maybe_warn_operand.
	Also call for function calls.
	(pass_late_warn_uninitialized::execute): Adjust comments.
	(execute_early_warn_uninitialized): Same.

gcc/testsuite/ChangeLog:

	PR middle-end/10138
	PR middle-end/95136
	* c-c++-common/Wsizeof-pointer-memaccess1.c: Prune out valid
	Wuninitialized.
	* c-c++-common/uninit-pr51010.c: Adjust expected warning format.
	* c-c++-common/goacc/uninit-dim-clause.c: Same.
	* c-c++-common/goacc/uninit-firstprivate-clause.c: Same.
	* c-c++-common/goacc/uninit-if-clause.c: Same.
	* c-c++-common/gomp/pr70550-1.c: Same.
	* c-c++-common/gomp/pr70550-2.c: Adjust.
	* g++.dg/20090107-1.C: Same.
	* g++.dg/20090121-1.C: Same.
	* g++.dg/ext/attr-access.C: Avoid -Wuninitialized.
	* gcc.dg/tree-ssa/forwprop-6.c: Prune out -Wuninitialized.
	* gcc.dg/Warray-bounds-52.c: Prune out valid -Wuninitialized.
	* gcc.dg/Warray-bounds-53.c: Same.
	* gcc.dg/Warray-bounds-54.c: Same.
	* gcc.dg/Wstringop-overflow-33.c: New test.
	* gcc.dg/attr-access-none.c: New test.
	* gcc.dg/attr-access-read-only.c: Adjust.
	* gcc.dg/attr-access-read-write.c: Same.
	* gcc.dg/attr-access-write-only.c: Same.
	* gcc.dg/pr71581.c: Adjust text of expected warning.
	* gcc.dg/uninit-15.c: Same.
	* gcc.dg/uninit-32.c: New test.
	* gcc.dg/uninit-33.c: New test.
	* gcc.dg/uninit-34.c: New test.
	* gcc.dg/uninit-36.c: New test.
	* gcc.dg/uninit-B-O0.c: Adjust text of expected warning.
	* gcc.dg/uninit-I-O0.c: Same.
	* gcc.dg/uninit-pr19430-O0.c: Same.
	* gcc.dg/uninit-pr19430.c: Same.
	* gcc.dg/uninit-pr95136.c: New test.
	* gfortran.dg/assignment_4.f90: Expect -Wuninitialized.
	* gfortran.dg/goacc/uninit-dim-clause.f95: Adjust text of expected
	warning.
	* gfortran.dg/goacc/uninit-firstprivate-clause.f95
	* gfortran.dg/goacc/uninit-if-clause.f95
	* gfortran.dg/pr66545_2.f90

1 files changed, 10 insertions, 2 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index cced19d..e656e66 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -2497,8 +2497,8 @@ may be diagnosed by warnings such as @option{-Wstringop-overflow},
 The @code{access} attribute specifies that a function to whose by-reference
 arguments the attribute applies accesses the referenced object according to
 @var{access-mode}.  The @var{access-mode} argument is required and must be
-one of three names: @code{read_only}, @code{read_write}, or @code{write_only}.
-The remaining two are positional arguments.
+one of four names: @code{read_only}, @code{read_write}, @code{write_only},
+or @code{none}.  The remaining two are positional arguments.
 
 The required @var{ref-index} positional argument  denotes a function
 argument of pointer (or in C++, reference) type that is subject to
@@ -2555,6 +2555,14 @@ __attribute__ ((access (write_only, 1), access (read_only, 2))) char* strcpy (ch
 __attribute__ ((access (write_only, 1, 2), access (read_write, 3))) int fgets (char*, int, FILE*);
 @end smallexample
 
+The access mode @code{none} specifies that the pointer to which it applies
+is not used to access the referenced object at all.  Unless the pointer is
+null the pointed-to object must exist and have at least the size as denoted
+by the @var{size-index} argument.  The object need not be initialized.
+The mode is intended to be used as a means to help validate the expected
+object size, for example in functions that call @code{__builtin_object_size}.
+@xref{Object Size Checking}.
+
 @item alias ("@var{target}")
 @cindex @code{alias} function attribute
 The @code{alias} attribute causes the declaration to be emitted as an alias