[Bug c/91463] missing -Warray-bounds accessing past the end of a statically initialized flexible array member

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91463

--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> ---
Author: msebor
Date: Fri Nov  1 21:09:20 2019
New Revision: 277728

URL: https://gcc.gnu.org/viewcvs?rev=277728&root=gcc&view=rev
Log:
PR middle-end/91679 - missing -Warray-bounds accessing a member array in a
local buffer
PR middle-end/91647 - new FAILs for Warray-bounds-8 and Wstringop-overflow-3.C
PR middle-end/91463 - missing -Warray-bounds accessing past the end of a
statically initialized flexible array member
PR middle-end/92312 - bogus -Wstringop-overflow storing into a trailing array
backed by larger buffer

gcc/ChangeLog:

        PR middle-end/91679
        PR middle-end/91647
        PR middle-end/91463
        PR middle-end/92312
        * c-family/c-pretty-print.c (direct_abstract_declarator): Print
        bound in zero-length arrays.
        * gcc/c-family/c.opt (-Wzero-length-bounds): New option.
        * gcc/doc/invoke.texi (-Wzero-length-bounds): Document.
        * gimple-match-head.c (try_conditional_simplification): Use memcpy
        instead of a hand-rolled loop to avoid PR 92323.
        * tree-vrp.c (vrp_prop::check_array_ref): Handle trailing arrays
        with initializers.
        (vrp_prop::check_mem_ref): Handle declared struct objects.
        * tree.c (last_field): New function.
        (array_at_struct_end_p): Handle MEM_REF.
        (get_initializer_for): New helper.
        (component_ref_size): Add argument.  Rename locals.  Call
        get_initializer_for instead of fold_ctor_reference.  Correct handling
        of flexible array members.
        * wide-int.h (generic_wide_int <storage>::sign_mask): Assert invariant.

gcc/testsuite/ChangeLog:

        PR middle-end/91679
        PR middle-end/91647
        PR middle-end/91463
        PR middle-end/92312
        * c-c++-common/Warray-bounds-2.c: Disable VRP.  Adjust expected
messages.
        * g++.dg/warn/Warray-bounds-8.C: Remove xfails.
        * gcc.dg/Warray-bounds-48.c: New test.
        * gcc.dg/Warray-bounds-49.c: New test.
        * gcc.dg/Wstringop-overflow-16.c: Adjust text of expected messages.
        * gcc.dg/Wstringop-overflow-21.c: New test.
        * gcc.dg/Wzero-length-array-bounds.c: New test.
        * gcc.dg/pr36902.c: Remove xfail.
        * gcc.dg/strlenopt-57.c: Add an expected warning.


Added:
    trunk/gcc/testsuite/gcc.dg/Warray-bounds-48.c
    trunk/gcc/testsuite/gcc.dg/Warray-bounds-49.c
    trunk/gcc/testsuite/gcc.dg/Wstringop-overflow-21.c
    trunk/gcc/testsuite/gcc.dg/Wzero-length-array-bounds.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-family/c-pretty-print.c
    trunk/gcc/c-family/c.opt
    trunk/gcc/doc/invoke.texi
    trunk/gcc/gimple-match-head.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/c-c++-common/Warray-bounds-2.c
    trunk/gcc/testsuite/g++.dg/warn/Warray-bounds-8.C
    trunk/gcc/testsuite/gcc.dg/Warray-bounds-46.c
    trunk/gcc/testsuite/gcc.dg/Wstringop-overflow-16.c
    trunk/gcc/testsuite/gcc.dg/pr36902.c
    trunk/gcc/testsuite/gcc.dg/strlenopt-57.c
    trunk/gcc/tree-vrp.c
    trunk/gcc/tree.c
    trunk/gcc/tree.h
    trunk/gcc/wide-int.h