Hi, Richard,
I guess that we now agreed on the following:
“ the information that we ran into a trailing array but didn't consider
it a flex array because of -fstrict-flex-arrays is always a useful information”
The only thing we didn’t decide is:
A. Amend such new information to -Warray-bounds when -fstrict-flex-arrays=N
(N>0) specified.
OR
B. Issue such new information with a new warning option -Wstrict-flex-arrays
when -fstrict-flex-arrays=N (N>0) specified.
My current patch implemented B.
If you think A is better, I will change the patch as A.
Let me know your opinion.
thanks.
Qing
> On Dec 14, 2022, at 4:03 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Tue, 13 Dec 2022, Qing Zhao wrote:
>
>> Richard,
>>
>> Do you have any decision on this one?
>> Do we need this warning option For GCC?
>
> Looking at the testcases it seems that the diagnostic amends
> -Warray-bounds diagnostics for trailing but not flexible arrays?
> Wouldn't it be better to generally diagnose this, so have
> -Warray-bounds, with -fstrict-flex-arrays, for
>
> struct X { int a[1]; };
> int foo (struct X *p)
> {
> return p->a[1];
> }
>
> emit
>
> warning: array subscript 1 is above array bounds ...
> note: the trailing array is only a flexible array member with
> -fno-strict-flex-arrays
>
> ? Having -Wstrict-flex-arrays=N and N not agree with the
> -fstrict-flex-arrays level sounds hardly useful to me but the
> information that we ran into a trailing array but didn't consider
> it a flex array because of -fstrict-flex-arrays is always a
> useful information?
>
> But maybe I misunderstood this new diagnostic?
>
> Thanks,
> Richard.
>
>
>> thanks.
>>
>> Qing
>>
>>> On Dec 6, 2022, at 11:18 AM, Qing Zhao <qing.z...@oracle.com> wrote:
>>>
>>> '-Wstrict-flex-arrays'
>>> Warn about inproper usages of flexible array members according to
>>> the LEVEL of the 'strict_flex_array (LEVEL)' attribute attached to
>>> the trailing array field of a structure if it's available,
>>> otherwise according to the LEVEL of the option
>>> '-fstrict-flex-arrays=LEVEL'.
>>>
>>> This option is effective only when LEVEL is bigger than 0.
>>> Otherwise, it will be ignored with a warning.
>>>
>>> when LEVEL=1, warnings will be issued for a trailing array
>>> reference of a structure that have 2 or more elements if the
>>> trailing array is referenced as a flexible array member.
>>>
>>> when LEVEL=2, in addition to LEVEL=1, additional warnings will be
>>> issued for a trailing one-element array reference of a structure if
>>> the array is referenced as a flexible array member.
>>>
>>> when LEVEL=3, in addition to LEVEL=2, additional warnings will be
>>> issued for a trailing zero-length array reference of a structure if
>>> the array is referenced as a flexible array member.
>>>
>>> gcc/ChangeLog:
>>>
>>> * doc/invoke.texi: Document -Wstrict-flex-arrays option.
>>> * gimple-array-bounds.cc (check_out_of_bounds_and_warn): Add two more
>>> arguments.
>>> (array_bounds_checker::check_array_ref): Issue warnings for
>>> -Wstrict-flex-arrays.
>>> * opts.cc (finish_options): Issue warning for unsupported combination
>>> of -Wstrict_flex_arrays and -fstrict-flex-array.
>>> * tree-vrp.cc (execute_ranger_vrp): Enable the pass when
>>> warn_strict_flex_array is true.
>>>
>>> gcc/c-family/ChangeLog:
>>>
>>> * c.opt (Wstrict-flex-arrays): New option.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> * gcc.dg/Warray-bounds-flex-arrays-1.c: Update testing case with
>>> -Wstrict-flex-arrays.
>>> * gcc.dg/Warray-bounds-flex-arrays-2.c: Likewise.
>>> * gcc.dg/Warray-bounds-flex-arrays-3.c: Likewise.
>>> * gcc.dg/Warray-bounds-flex-arrays-4.c: Likewise.
>>> * gcc.dg/Warray-bounds-flex-arrays-5.c: Likewise.
>>> * gcc.dg/Warray-bounds-flex-arrays-6.c: Likewise.
>>> * c-c++-common/Wstrict-flex-arrays.c: New test.
>>> * gcc.dg/Wstrict-flex-arrays-2.c: New test.
>>> * gcc.dg/Wstrict-flex-arrays-3.c: New test.
>>> * gcc.dg/Wstrict-flex-arrays.c: New test.
>>> ---
>>> gcc/c-family/c.opt | 5 +
>>> gcc/doc/invoke.texi | 27 ++++-
>>> gcc/gimple-array-bounds.cc | 103 ++++++++++++++----
>>> gcc/opts.cc | 8 ++
>>> .../c-c++-common/Wstrict-flex-arrays.c | 9 ++
>>> .../gcc.dg/Warray-bounds-flex-arrays-1.c | 5 +-
>>> .../gcc.dg/Warray-bounds-flex-arrays-2.c | 6 +-
>>> .../gcc.dg/Warray-bounds-flex-arrays-3.c | 7 +-
>>> .../gcc.dg/Warray-bounds-flex-arrays-4.c | 5 +-
>>> .../gcc.dg/Warray-bounds-flex-arrays-5.c | 6 +-
>>> .../gcc.dg/Warray-bounds-flex-arrays-6.c | 7 +-
>>> gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c | 39 +++++++
>>> gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c | 39 +++++++
>>> gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c | 39 +++++++
>>> gcc/tree-vrp.cc | 2 +-
>>> 15 files changed, 273 insertions(+), 34 deletions(-)
>>> create mode 100644 gcc/testsuite/c-c++-common/Wstrict-flex-arrays.c
>>> create mode 100644 gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
>>> create mode 100644 gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
>>> create mode 100644 gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
>>>
>>> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>>> index 0d0ad0a6374..33edeefd285 100644
>>> --- a/gcc/c-family/c.opt
>>> +++ b/gcc/c-family/c.opt
>>> @@ -976,6 +976,11 @@ Wstringop-truncation
>>> C ObjC C++ LTO ObjC++ Var(warn_stringop_truncation) Warning Init (1)
>>> LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
>>> Warn about truncation in string manipulation functions like strncat and
>>> strncpy.
>>>
>>> +Wstrict-flex-arrays
>>> +C C++ Var(warn_strict_flex_arrays) Warning
>>> +Warn about inproper usages of flexible array members
>>> +according to the level of -fstrict-flex-arrays.
>>> +
>>> Wsuggest-attribute=format
>>> C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
>>> Warn about functions which might be candidates for format attributes.
>>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>>> index 726392409b6..4402b0427ef 100644
>>> --- a/gcc/doc/invoke.texi
>>> +++ b/gcc/doc/invoke.texi
>>> @@ -398,7 +398,7 @@ Objective-C and Objective-C++ Dialects}.
>>> -Wstrict-aliasing=n -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
>>> -Wstring-compare @gol
>>> -Wno-stringop-overflow -Wno-stringop-overread @gol
>>> --Wno-stringop-truncation @gol
>>> +-Wno-stringop-truncation -Wstrict-flex-arrays @gol
>>> -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]}
>>> @gol
>>> -Wswitch -Wno-switch-bool -Wswitch-default -Wswitch-enum @gol
>>> -Wno-switch-outside-range -Wno-switch-unreachable -Wsync-nand @gol
>>> @@ -7835,6 +7835,31 @@ however, are not suitable arguments to functions
>>> that expect
>>> such arrays GCC issues warnings unless it can prove that the use is
>>> safe. @xref{Common Variable Attributes}.
>>>
>>> +@item -Wstrict-flex-arrays
>>> +@opindex Wstrict-flex-arrays
>>> +@opindex Wno-strict-flex-arrays
>>> +Warn about inproper usages of flexible array members
>>> +according to the @var{level} of the @code{strict_flex_array (@var{level})}
>>> +attribute attached to the trailing array field of a structure if it's
>>> +available, otherwise according to the @var{level} of the option
>>> +@option{-fstrict-flex-arrays=@var{level}}.
>>> +
>>> +This option is effective only when @var{level} is bigger than 0.
>>> Otherwise,
>>> +it will be ignored with a warning.
>>> +
>>> +when @var{level}=1, warnings will be issued for a trailing array reference
>>> +of a structure that have 2 or more elements if the trailing array is
>>> referenced
>>> +as a flexible array member.
>>> +
>>> +when @var{level}=2, in addition to @var{level}=1, additional warnings will
>>> be
>>> +issued for a trailing one-element array reference of a structure
>>> +if the array is referenced as a flexible array member.
>>> +
>>> +when @var{level}=3, in addition to @var{level}=2, additional warnings will
>>> be
>>> +issued for a trailing zero-length array reference of a structure
>>> +if the array is referenced as a flexible array member.
>>> +
>>> +
>>> @item
>>> -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}cold@r{|}malloc@r{]}
>>> @opindex Wsuggest-attribute=
>>> @opindex Wno-suggest-attribute=
>>> diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
>>> index db3459af325..825f11331b5 100644
>>> --- a/gcc/gimple-array-bounds.cc
>>> +++ b/gcc/gimple-array-bounds.cc
>>> @@ -252,25 +252,34 @@ get_up_bounds_for_array_ref (tree ref, tree *decl,
>>>
>>> /* Given the LOW_SUB_ORG, LOW_SUB and UP_SUB, and the computed UP_BOUND
>>> and UP_BOUND_P1, check whether the array reference REF is out of bound.
>>> - Issue warnings if out of bound, return TRUE if warnings are issued. */
>>> + When out of bounds, set OUT_OF_BOUND to true.
>>> + Issue warnings if FOR_ARRAY_BOUND is true.
>>> + return TRUE if warnings are issued. */
>>> +
>>>
>>> static bool
>>> check_out_of_bounds_and_warn (location_t location, tree ref,
>>> tree low_sub_org, tree low_sub, tree up_sub,
>>> tree up_bound, tree up_bound_p1,
>>> const value_range *vr,
>>> - bool ignore_off_by_one)
>>> + bool ignore_off_by_one, bool for_array_bound,
>>> + bool *out_of_bound)
>>> {
>>> tree low_bound = array_ref_low_bound (ref);
>>> tree artype = TREE_TYPE (TREE_OPERAND (ref, 0));
>>>
>>> bool warned = false;
>>> + *out_of_bound = false;
>>>
>>> /* Empty array. */
>>> if (up_bound && tree_int_cst_equal (low_bound, up_bound_p1))
>>> - warned = warning_at (location, OPT_Warray_bounds_,
>>> - "array subscript %E is outside array bounds of %qT",
>>> - low_sub_org, artype);
>>> + {
>>> + *out_of_bound = true;
>>> + if (for_array_bound)
>>> + warned = warning_at (location, OPT_Warray_bounds_,
>>> + "array subscript %E is outside array"
>>> + " bounds of %qT", low_sub_org, artype);
>>> + }
>>>
>>> if (warned)
>>> ; /* Do nothing. */
>>> @@ -283,24 +292,33 @@ check_out_of_bounds_and_warn (location_t location,
>>> tree ref,
>>> : tree_int_cst_le (up_bound, up_sub))
>>> && TREE_CODE (low_sub) == INTEGER_CST
>>> && tree_int_cst_le (low_sub, low_bound))
>>> - warned = warning_at (location, OPT_Warray_bounds_,
>>> - "array subscript [%E, %E] is outside "
>>> - "array bounds of %qT",
>>> - low_sub, up_sub, artype);
>>> + {
>>> + *out_of_bound = true;
>>> + warned = warning_at (location, OPT_Warray_bounds_,
>>> + "array subscript [%E, %E] is outside "
>>> + "array bounds of %qT",
>>> + low_sub, up_sub, artype);
>>> + }
>>> }
>>> else if (up_bound
>>> && TREE_CODE (up_sub) == INTEGER_CST
>>> && (ignore_off_by_one
>>> ? !tree_int_cst_le (up_sub, up_bound_p1)
>>> : !tree_int_cst_le (up_sub, up_bound)))
>>> - warned = warning_at (location, OPT_Warray_bounds_,
>>> - "array subscript %E is above array bounds of %qT",
>>> - up_sub, artype);
>>> + {
>>> + *out_of_bound = true;
>>> + warned = warning_at (location, OPT_Warray_bounds_,
>>> + "array subscript %E is above array bounds of %qT",
>>> + up_sub, artype);
>>> + }
>>> else if (TREE_CODE (low_sub) == INTEGER_CST
>>> && tree_int_cst_lt (low_sub, low_bound))
>>> - warned = warning_at (location, OPT_Warray_bounds_,
>>> - "array subscript %E is below array bounds of %qT",
>>> - low_sub, artype);
>>> + {
>>> + *out_of_bound = true;
>>> + warned = warning_at (location, OPT_Warray_bounds_,
>>> + "array subscript %E is below array bounds of %qT",
>>> + low_sub, artype);
>>> + }
>>> return warned;
>>> }
>>>
>>> @@ -333,14 +351,21 @@ array_bounds_checker::check_array_ref (location_t
>>> location, tree ref,
>>>
>>> tree arg = TREE_OPERAND (ref, 0);
>>> const bool compref = TREE_CODE (arg) == COMPONENT_REF;
>>> + unsigned int strict_flex_array_level = flag_strict_flex_arrays;
>>>
>>> if (compref)
>>> - /* Try to determine special array member type for this COMPONENT_REF.
>>> */
>>> - sam = component_ref_sam_type (arg);
>>> + {
>>> + /* Try to determine special array member type for this
>>> COMPONENT_REF. */
>>> + sam = component_ref_sam_type (arg);
>>> + /* Get the level of strict_flex_array for this array field. */
>>> + tree afield_decl = TREE_OPERAND (arg, 1);
>>> + strict_flex_array_level = strict_flex_array_level_of (afield_decl);
>>> + }
>>>
>>> get_up_bounds_for_array_ref (ref, &decl, &up_bound, &up_bound_p1);
>>>
>>> bool warned = false;
>>> + bool out_of_bound = false;
>>>
>>> tree artype = TREE_TYPE (TREE_OPERAND (ref, 0));
>>> tree low_sub_org = TREE_OPERAND (ref, 1);
>>> @@ -361,7 +386,8 @@ array_bounds_checker::check_array_ref (location_t
>>> location, tree ref,
>>> warned = check_out_of_bounds_and_warn (location, ref,
>>> low_sub_org, low_sub, up_sub,
>>> up_bound, up_bound_p1, vr,
>>> - ignore_off_by_one);
>>> + ignore_off_by_one, warn_array_bounds,
>>> + &out_of_bound);
>>>
>>>
>>> if (!warned && sam == special_array_member::int_0)
>>> @@ -373,19 +399,56 @@ array_bounds_checker::check_array_ref (location_t
>>> location, tree ref,
>>> "of an interior zero-length array %qT")),
>>> low_sub, artype);
>>>
>>> - if (warned)
>>> + if (warned || out_of_bound)
>>> {
>>> - if (dump_file && (dump_flags & TDF_DETAILS))
>>> + if (warned && dump_file && (dump_flags & TDF_DETAILS))
>>> {
>>> fprintf (dump_file, "Array bound warning for ");
>>> dump_generic_expr (MSG_NOTE, TDF_SLIM, ref);
>>> fprintf (dump_file, "\n");
>>> }
>>>
>>> + /* issue warnings for -Wstrict-flex-arrays according to the level of
>>> + flag_strict_flex_arrays. */
>>> + if (out_of_bound && warn_strict_flex_arrays)
>>> + switch (strict_flex_array_level)
>>> + {
>>> + case 3:
>>> + /* Issue additional warnings for trailing arrays [0]. */
>>> + if (sam == special_array_member::trail_0)
>>> + warned = warning_at (location, OPT_Wstrict_flex_arrays,
>>> + "trailing array %qT should not be used as "
>>> + "a flexible array member for level 3",
>>> + artype);
>>> + /* FALLTHROUGH. */
>>> + case 2:
>>> + /* Issue additional warnings for trailing arrays [1]. */
>>> + if (sam == special_array_member::trail_1)
>>> + warned = warning_at (location, OPT_Wstrict_flex_arrays,
>>> + "trailing array %qT should not be used as "
>>> + "a flexible array member for level 2 and "
>>> + "above", artype);
>>> + /* FALLTHROUGH. */
>>> + case 1:
>>> + /* Issue warnings for trailing arrays [n]. */
>>> + if (sam == special_array_member::trail_n)
>>> + warned = warning_at (location, OPT_Wstrict_flex_arrays,
>>> + "trailing array %qT should not be used as "
>>> + "a flexible array member for level 1 and "
>>> + "above", artype);
>>> + break;
>>> + case 0:
>>> + /* Do nothing. */
>>> + break;
>>> + default:
>>> + gcc_unreachable ();
>>> + }
>>> +
>>> /* Avoid more warnings when checking more significant subscripts
>>> of the same expression. */
>>> ref = TREE_OPERAND (ref, 0);
>>> suppress_warning (ref, OPT_Warray_bounds_);
>>> + suppress_warning (ref, OPT_Wstrict_flex_arrays);
>>>
>>> if (decl)
>>> ref = decl;
>>> diff --git a/gcc/opts.cc b/gcc/opts.cc
>>> index 73fc97756e4..8db53ad6c77 100644
>>> --- a/gcc/opts.cc
>>> +++ b/gcc/opts.cc
>>> @@ -1411,6 +1411,14 @@ finish_options (struct gcc_options *opts, struct
>>> gcc_options *opts_set,
>>> opts->x_profile_flag = 0;
>>> }
>>>
>>> + if (opts->x_warn_strict_flex_arrays)
>>> + if (opts->x_flag_strict_flex_arrays == 0)
>>> + {
>>> + opts->x_warn_strict_flex_arrays = 0;
>>> + warning_at (UNKNOWN_LOCATION, 0,
>>> + "%<-Wstrict-flex-arrays%> is ignored when"
>>> + " %<-fstrict-flex-arrays%> does not present");
>>> + }
>>>
>>> diagnose_options (opts, opts_set, loc);
>>> }
>>> diff --git a/gcc/testsuite/c-c++-common/Wstrict-flex-arrays.c
>>> b/gcc/testsuite/c-c++-common/Wstrict-flex-arrays.c
>>> new file mode 100644
>>> index 00000000000..72b4b7c6406
>>> --- /dev/null
>>> +++ b/gcc/testsuite/c-c++-common/Wstrict-flex-arrays.c
>>> @@ -0,0 +1,9 @@
>>> +/* Test the usage of option -Wstrict-flex-arrays. */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays" } */
>>> +
>>> +int main(int argc, char *argv[])
>>> +{
>>> + return 0;
>>> +}
>>> +/* { dg-warning "is ignored when \'-fstrict-flex-arrays\' does not
>>> present" "" { target *-*-* } 0 } */
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
>>> index d36ba4d86cb..65c9fec43af 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-1.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds + -Wstrict-flex-arrays. */
>>> /* { dg-do compile} */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=1 -Warray-bounds" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=1
>>> -Warray-bounds" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,6 +32,7 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above
>>> array bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /* { dg-bogus "array subscript " } */
>>> trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
>>> index f63206e1948..2b5a895c598 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-2.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds + -Wstrict-flex-arrays. */
>>> /* { dg-do compile } */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=2 -Warray-bounds" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=2
>>> -Warray-bounds" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,7 +32,9 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above
>>> array bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /* { dg-warning "array subscript 2 is above array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
>>> trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
>>>
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
>>> index e3273714e8b..25b903f2615 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-3.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds + -Wstrict-flex-arrays. */
>>> /* { dg-do compile } */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=3 -Warray-bounds" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=3
>>> -Warray-bounds" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,8 +32,11 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above
>>> array bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
>>> trailing_0->c[1] = 1; /*{ dg-warning "array subscript 1 is outside array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 3" "" { target *-*-* } .-1 } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript" } */
>>>
>>> }
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
>>> index cabaea77dc2..5fc500a19ca 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-4.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds=2. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds=2 + -Wstrict-flex-arrays. */
>>> /* { dg-do compile } */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=1 -Warray-bounds=2" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=1
>>> -Warray-bounds=2" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,6 +32,7 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above
>>> array bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /* { dg-bogus "array subscript " } */
>>> trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
>>> index 8b7db6e4f39..30bb4ca8832 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-5.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds=2. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds=2 + -Wstrict-flex-arrays. */
>>> /* { dg-do compile } */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=2 -Warray-bounds=2" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=2
>>> -Warray-bounds=2" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,7 +32,9 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above array
>>> bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
>>> trailing_0->c[1] = 1; /* { dg-bogus "array subscript " } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
>>>
>>> diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
>>> b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
>>> index 035bf481396..e847a44516e 100644
>>> --- a/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
>>> +++ b/gcc/testsuite/gcc.dg/Warray-bounds-flex-arrays-6.c
>>> @@ -1,6 +1,6 @@
>>> -/* Test -fstrict-flex-arrays + -Warray-bounds=2. */
>>> +/* Test -fstrict-flex-arrays + -Warray-bounds=2 + -Wstrict-flex-arrays. */
>>> /* { dg-do compile } */
>>> -/* { dg-options "-O2 -fstrict-flex-arrays=3 -Warray-bounds=2" } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=3
>>> -Warray-bounds=2" } */
>>>
>>> struct trailing_array_1 {
>>> int a;
>>> @@ -32,8 +32,11 @@ void __attribute__((__noinline__)) stuff(
>>> struct trailing_array_4 *trailing_flex)
>>> {
>>> normal->c[5] = 5; /*{ dg-warning "array subscript 5 is above
>>> array bounds of" } */
>>> + /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" "" { target *-*-* } .-1 } */
>>> trailing_1->c[2] = 2; /*{ dg-warning "array subscript 2 is above array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" "" { target *-*-* } .-1 } */
>>> trailing_0->c[1] = 1; /*{ dg-warning "array subscript 1 is outside array
>>> bounds of" } */
>>> + /* { dg-warning "should not be used as a
>>> flexible array member for level 3" "" { target *-*-* } .-1 } */
>>> trailing_flex->c[10] = 10; /* { dg-bogus "array subscript " } */
>>>
>>> }
>>> diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
>>> b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
>>> new file mode 100644
>>> index 00000000000..2e241f96208
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-2.c
>>> @@ -0,0 +1,39 @@
>>> +/* Test -Wstrict-flex-arrays. */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=2" } */
>>> +
>>> +struct trailing_array_1 {
>>> + int a;
>>> + int b;
>>> + int c[4];
>>> +};
>>> +
>>> +struct trailing_array_2 {
>>> + int a;
>>> + int b;
>>> + int c[1];
>>> +};
>>> +
>>> +struct trailing_array_3 {
>>> + int a;
>>> + int b;
>>> + int c[0];
>>> +};
>>> +struct trailing_array_4 {
>>> + int a;
>>> + int b;
>>> + int c[];
>>> +};
>>> +
>>> +void __attribute__((__noinline__)) stuff(
>>> + struct trailing_array_1 *normal,
>>> + struct trailing_array_2 *trailing_1,
>>> + struct trailing_array_3 *trailing_0,
>>> + struct trailing_array_4 *trailing_flex)
>>> +{
>>> + normal->c[5] = 5; /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" } */
>>> + trailing_1->c[2] = 2; /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" } */
>>> + trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible
>>> array member for level 2 and above" } */
>>> + trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a
>>> flexible array member for level 2 and above" } */
>>> +
>>> +}
>>> diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
>>> b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
>>> new file mode 100644
>>> index 00000000000..97eb65ba0a9
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays-3.c
>>> @@ -0,0 +1,39 @@
>>> +/* Test -Wstrict-flex-arrays. */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=3" } */
>>> +
>>> +struct trailing_array_1 {
>>> + int a;
>>> + int b;
>>> + int c[4];
>>> +};
>>> +
>>> +struct trailing_array_2 {
>>> + int a;
>>> + int b;
>>> + int c[1];
>>> +};
>>> +
>>> +struct trailing_array_3 {
>>> + int a;
>>> + int b;
>>> + int c[0];
>>> +};
>>> +struct trailing_array_4 {
>>> + int a;
>>> + int b;
>>> + int c[];
>>> +};
>>> +
>>> +void __attribute__((__noinline__)) stuff(
>>> + struct trailing_array_1 *normal,
>>> + struct trailing_array_2 *trailing_1,
>>> + struct trailing_array_3 *trailing_0,
>>> + struct trailing_array_4 *trailing_flex)
>>> +{
>>> + normal->c[5] = 5; /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" } */
>>> + trailing_1->c[2] = 2; /* { dg-warning "should not be used as a
>>> flexible array member for level 2 and above" } */
>>> + trailing_0->c[1] = 1; /* { dg-warning "should not be used as a
>>> flexible array member for level 3" } */
>>> + trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a
>>> flexible array member for level 3" } */
>>> +
>>> +}
>>> diff --git a/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
>>> b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
>>> new file mode 100644
>>> index 00000000000..110fdc72778
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.dg/Wstrict-flex-arrays.c
>>> @@ -0,0 +1,39 @@
>>> +/* Test -Wstrict-flex-arrays. */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-O2 -Wstrict-flex-arrays -fstrict-flex-arrays=1" } */
>>> +
>>> +struct trailing_array_1 {
>>> + int a;
>>> + int b;
>>> + int c[4];
>>> +};
>>> +
>>> +struct trailing_array_2 {
>>> + int a;
>>> + int b;
>>> + int c[1];
>>> +};
>>> +
>>> +struct trailing_array_3 {
>>> + int a;
>>> + int b;
>>> + int c[0];
>>> +};
>>> +struct trailing_array_4 {
>>> + int a;
>>> + int b;
>>> + int c[];
>>> +};
>>> +
>>> +void __attribute__((__noinline__)) stuff(
>>> + struct trailing_array_1 *normal,
>>> + struct trailing_array_2 *trailing_1,
>>> + struct trailing_array_3 *trailing_0,
>>> + struct trailing_array_4 *trailing_flex)
>>> +{
>>> + normal->c[5] = 5; /*{ dg-warning "should not be used as a
>>> flexible array member for level 1 and above" } */
>>> + trailing_1->c[2] = 2; /* { dg-bogus "should not be used as a flexible
>>> array member for level 1 and above" } */
>>> + trailing_0->c[1] = 1; /* { dg-bogus "should not be used as a flexible
>>> array member for level 1 and above" } */
>>> + trailing_flex->c[10] = 10; /* { dg-bogus "should not be used as a
>>> flexible array member for level 1 and above" } */
>>> +
>>> +}
>>> diff --git a/gcc/tree-vrp.cc b/gcc/tree-vrp.cc
>>> index 3846dc1d849..e6c6c5a301d 100644
>>> --- a/gcc/tree-vrp.cc
>>> +++ b/gcc/tree-vrp.cc
>>> @@ -1087,7 +1087,7 @@ execute_ranger_vrp (struct function *fun, bool
>>> warn_array_bounds_p,
>>> if (dump_file && (dump_flags & TDF_DETAILS))
>>> ranger->dump (dump_file);
>>>
>>> - if (warn_array_bounds && warn_array_bounds_p)
>>> + if ((warn_array_bounds || warn_strict_flex_arrays) &&
>>> warn_array_bounds_p)
>>> {
>>> // Set all edges as executable, except those ranger says aren't.
>>> int non_exec_flag = ranger->non_executable_edge_flag;
>>> --
>>> 2.31.1
>>>
>>
>>
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
> Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
> HRB 36809 (AG Nuernberg)
