Re: Ping---[V3][PATCH 2/2] Add a new warning option -Wstrict-flex-arrays.

[Qing Zhao <qing.zhao@oracle.com>]

FYI.

Committed this last patch as:
https://jira.oci.oraclecorp.com/browse/OLDIS-21095

I will come up with the update to gcc-13/changes.html for -fstrict-flex-arrays very soon.

Thanks.

Qing
> On Dec 16, 2022, at 9:49 AM, Qing Zhao via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> 
> 
> 
>> On Dec 16, 2022, at 4:17 AM, Richard Biener <rguenther@suse.de> wrote:
>> 
>> On Thu, 15 Dec 2022, Qing Zhao wrote:
>> 
>>> 
>>> 
>>>> On Dec 15, 2022, at 2:47 AM, Richard Biener <rguenther@suse.de> wrote:
>>>> 
>>>> On Wed, 14 Dec 2022, Qing Zhao wrote:
>>>> 
>>>>> 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. 
>>>> 
>>>> Plus it implements it to specify a different flex-array variant for
>>>> the extra diagnostic.
>>> Could you clarify a little bit on this? (Don’t quite understand…)
>>>> 
>>>>> If you think A is better, I will change the patch as A. 
>>>> 
>>>> I would tend to A since, as I said, it's useful information that
>>>> shouldn't be hidden and not adding an option removes odd combination
>>>> possibilities such as -Wno-array-bounds -Wstrict-flex-arrays.
>>> 
>>> With current implementation, the above combination will ONLY report the 
>>> misuse of trailing array as flex-array.  No out-of-bounds warnings 
>>> issued.
>>> 
>>>> In particular I find, say, -fstrict-flex-arrays=2 -Wstrict-flex-arrays=1
>>>> hardly useful.
>>> 
>>> The above combination will NOT happen, because there is NO level argument for -Wstrict-flex-arrays.
>>> 
>>> The only combination will be:    -fstrict-flex-arrays=N -Wstrict-flex-arrays
>>> 
>>> When N > 0, -Wstrict-flex-arrays will report any misuse of trailing arrays as flexible array per the value of N.
>>>> 
>>>> But I'm interested in other opinions.
>>> 
>>> Adding a separate -Wstrict-flex-arrays will provide users a choice to ONLY look at the mis-use of trailing arrays as flex-arrays.  Without this new option, such information will be buried into tons of out-of-bounds messges. 
>>> 
>>> I think this is the major benefit to have one separate new warning -Wstrict-flex-arrays. 
>>> 
>>> Do we need to provide the users this choice?
>> 
>> Ah, OK - I can see the value of auditing code this way before
>> enabling -fstrict-flex-arrays.
> Yes, I think the major benefit of this option is to help users to identify all the places where the trailing arrays are misused as flex-arrays at different level of -fstrict-flex-arrays=N, then update their source code accordingly. And finally can enable -fstrict-flex-arrays by default.
>> 
>>> +  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");
>> 
>> "is not present”.
> Okay.
>> 
>> The patch is OK with that change.
> Thanks! Will commit the patch after the change.
>> 
>> Thanks and sorry for the slow process ...
> 
> Thank you for your patience and questions.
> The discussion is very helpful since I was not 100% sure whether this new warning is necessary or not in the beginning, but now after this discussion I feel confident that it’s a necessary option to be added.
> 
> Qing
> 
>> 
>> Richard.
>> 
>>> Thanks.
>>> 
>>> Qing
>>>> 
>>>> Thanks,
>>>> Richard.
>>>> 
>>>>> Let me know your opinion.
>>>>> 
>>>>> thanks.
>>>>> 
>>>>> Qing
>>>>> 
>>>>> 
>>>>>> On Dec 14, 2022, at 4:03 AM, Richard Biener <rguenther@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.zhao@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 <rguenther@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)
>>>>> 
>>>>> 
>>>> 
>>>> -- 
>>>> Richard Biener <rguenther@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)
>>> 
>>> 
>> 
>> -- 
>> Richard Biener <rguenther@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)