> On Aug 26, 2022, at 4:48 AM, Richard Biener <rguent...@suse.de> wrote:
>
> On Wed, 17 Aug 2022, Qing Zhao wrote:
>
>> Add the following new option -fstrict-flex-array[=n] and a corresponding
>> attribute strict_flex_array to GCC:
>>
>> '-fstrict-flex-array'
>> Treat the trailing array of a structure as a flexible array member
>> in a stricter way. The positive form is equivalent to
>> '-fstrict-flex-array=3', which is the strictest. A trailing array
>> is treated as a flexible array member only when it is declared as a
>> flexible array member per C99 standard onwards. The negative form
>> is equivalent to '-fstrict-flex-array=0', which is the least
>> strict. All trailing arrays of structures are treated as flexible
>> array members.
>>
>> '-fstrict-flex-array=LEVEL'
>> Treat the trailing array of a structure as a flexible array member
>> in a stricter way. The value of LEVEL controls the level of
>> strictness.
>>
>> The possible values of LEVEL are the same as for the
>> 'strict_flex_array' attribute (*note Variable Attributes::).
>>
>> You can control this behavior for a specific trailing array field
>> of a structure by using the variable attribute 'strict_flex_array'
>> attribute (*note Variable Attributes::).
>>
>> This option is only valid when flexible array member is supported in the
>> language. FOR ISO C before C99 and ISO C++, no language support for the
>> flexible
>> array member at all, this option will be invalid and a warning will be
>> issued.
>> When -std=gnu89 is specified or C++ with GNU extension, only zero-length
>> array
>> extension and one-size array are supported, as a result, LEVEL=3 will be
>> invalid and a warning will be issued.
>>
>> 'strict_flex_array (LEVEL)'
>> The 'strict_flex_array' attribute should be attached to the
>> trailing array field of a structure. It specifies the level of
>> strictness of treating the trailing array field of a structure as a
>> flexible array member. LEVEL must be an integer betwen 0 to 3.
>>
>> LEVEL=0 is the least strict level, all trailing arrays of
>> structures are treated as flexible array members. LEVEL=3 is the
>> strictest level, only when the trailing array is declared as a
>> flexible array member per C99 standard onwards ([]), it is treated
>> as a flexible array member.
>>
>> There are two more levels in between 0 and 3, which are provided to
>> support older codes that use GCC zero-length array extension ([0])
>> or one-size array as flexible array member ([1]): When LEVEL is 1,
>> the trailing array is treated as a flexible array member when it is
>> declared as either [], [0], or [1]; When LEVEL is 2, the trailing
>> array is treated as a flexible array member when it is declared as
>> either [], or [0].
>>
>> This attribute can be used with or without '-fstrict-flex-array'.
>> When both the attribute and the option present at the same time,
>> the level of the strictness for the specific trailing array field
>> is determined by the attribute.
>>
>> This attribute is only valid when flexible array member is supported in
>> the
>> language. For ISO C before C99 and ISO C++, no language support for the
>> flexible
>> array member at all, this attribute will be invalid and a warning is
>> issued.
>> When -std=gnu89 is specified or C++ with GNU extension, only zero-length
>> array
>> extension and one-size array are supported, as a result, LEVEL=3 will be
>> invalid and a warning is issued.
>>
>> gcc/c-family/ChangeLog:
>>
>> * c-attribs.cc (handle_strict_flex_arrays_attribute): New function.
>> (c_common_attribute_table): New item for strict_flex_array.
>> * c-opts.cc (c_common_post_options): Handle the combination of
>> -fstrict-flex-arrays and -std specially.
>> * c.opt: (fstrict-flex-array): New option.
>> (fstrict-flex-array=): New option.
>>
>> gcc/c/ChangeLog:
>>
>> * c-decl.cc (flexible_array_member_type_p): New function.
>> (one_element_array_type_p): Likewise.
>> (zero_length_array_type_p): Likewise.
>> (add_flexible_array_elts_to_size): Call new utility
>> routine flexible_array_member_type_p.
>> (is_flexible_array_member_p): New function.
>> (finish_struct): Set the new DECL_NOT_FLEXARRAY flag.
>>
>> gcc/cp/ChangeLog:
>>
>> * module.cc (trees_out::core_bools): Stream out new bit
>> decl_not_flexarray.
>> (trees_in::core_bools): Stream in new bit decl_not_flexarray.
>>
>> gcc/ChangeLog:
>>
>> * doc/extend.texi: Document strict_flex_array attribute.
>> * doc/invoke.texi: Document -fstrict-flex-array[=n] option.
>> * print-tree.cc (print_node): Print new bit decl_not_flexarray.
>> * tree-core.h (struct tree_decl_common): New bit field
>> decl_not_flexarray.
>> * tree-streamer-in.cc (unpack_ts_decl_common_value_fields): Stream
>> in new bit decl_not_flexarray.
>> * tree-streamer-out.cc (pack_ts_decl_common_value_fields): Stream
>> out new bit decl_not_flexarray.
>> * tree.cc (array_at_struct_end_p): Update it with the new bit field
>> decl_not_flexarray.
>> * tree.h (DECL_NOT_FLEXARRAY): New fla
>
> The middle-end changes are OK, the c/ and cp/ changes need review
> from a frontend maintainer.
I CC’ed Joseph Myers for the FE part review. Joseph, could you please review
the changes in c-family and c?
And Nathan Sidwell for the C++ part, Nathan, could you please review the
changes in cp?
>
> Are the testcases actually C/C++ code? You can use
> testsuite/c-c++-common/ to place tests that run with both frontends.
The major issue when I tried to add these test cases into c-c++-common is,
these testing cases mainly for the options usage, for example, -std=c89,
-std=gnu89 for C, -std=c++98, -std=gnu++98 for C++.
For C and C++, the options that are tested are different. So, I am not sure how
can I put the same testing case for C and C++ but with different options?
Qing
>
> Richard.
>
>>
>> gcc/testsuite/ChangeLog:
>>
>> * g++.dg/strict-flex-array-1.C: New test.
>> * g++.dg/strict-flex-array-2.C: New test.
>> * g++.dg/strict-flex-array-3.C: New test.
>> * g++.dg/strict-flex-array-4.C: New test.
>> * gcc.dg/strict-flex-array-1.c: New test.
>> * gcc.dg/strict-flex-array-2.c: New test.
>> * gcc.dg/strict-flex-array-3.c: New test.
>> * gcc.dg/strict-flex-array-4.c: New test.
>> ---
>> gcc/c-family/c-attribs.cc | 94 +++++++++++++++
>> gcc/c-family/c-opts.cc | 41 +++++++
>> gcc/c-family/c.opt | 7 ++
>> gcc/c/c-decl.cc | 130 +++++++++++++++++++--
>> gcc/cp/module.cc | 2 +
>> gcc/doc/extend.texi | 33 ++++++
>> gcc/doc/invoke.texi | 34 +++++-
>> gcc/print-tree.cc | 8 +-
>> gcc/testsuite/g++.dg/strict-flex-array-1.C | 31 +++++
>> gcc/testsuite/g++.dg/strict-flex-array-2.C | 16 +++
>> gcc/testsuite/g++.dg/strict-flex-array-3.C | 21 ++++
>> gcc/testsuite/g++.dg/strict-flex-array-4.C | 9 ++
>> gcc/testsuite/gcc.dg/strict-flex-array-1.c | 31 +++++
>> gcc/testsuite/gcc.dg/strict-flex-array-2.c | 15 +++
>> gcc/testsuite/gcc.dg/strict-flex-array-3.c | 21 ++++
>> gcc/testsuite/gcc.dg/strict-flex-array-4.c | 10 ++
>> gcc/tree-core.h | 5 +-
>> gcc/tree-streamer-in.cc | 1 +
>> gcc/tree-streamer-out.cc | 1 +
>> gcc/tree.cc | 45 +++++--
>> gcc/tree.h | 14 ++-
>> 21 files changed, 541 insertions(+), 28 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/strict-flex-array-1.C
>> create mode 100644 gcc/testsuite/g++.dg/strict-flex-array-2.C
>> create mode 100644 gcc/testsuite/g++.dg/strict-flex-array-3.C
>> create mode 100644 gcc/testsuite/g++.dg/strict-flex-array-4.C
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-1.c
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> create mode 100644 gcc/testsuite/gcc.dg/strict-flex-array-4.c
>>
>> diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
>> index e4f1d3542f37..9c9927cefa0d 100644
>> --- a/gcc/c-family/c-attribs.cc
>> +++ b/gcc/c-family/c-attribs.cc
>> @@ -101,6 +101,8 @@ static tree handle_special_var_sec_attribute (tree *,
>> tree, tree, int, bool *);
>> static tree handle_aligned_attribute (tree *, tree, tree, int, bool *);
>> static tree handle_warn_if_not_aligned_attribute (tree *, tree, tree,
>> int, bool *);
>> +static tree handle_strict_flex_arrays_attribute (tree *, tree, tree,
>> + int, bool *);
>> static tree handle_weak_attribute (tree *, tree, tree, int, bool *) ;
>> static tree handle_noplt_attribute (tree *, tree, tree, int, bool *) ;
>> static tree handle_alias_ifunc_attribute (bool, tree *, tree, tree, bool *);
>> @@ -368,6 +370,8 @@ const struct attribute_spec c_common_attribute_table[] =
>> attr_aligned_exclusions },
>> { "warn_if_not_aligned", 0, 1, false, false, false, false,
>> handle_warn_if_not_aligned_attribute, NULL },
>> + { "strict_flex_arrays", 1, 1, false, false, false, false,
>> + handle_strict_flex_arrays_attribute, NULL },
>> { "weak", 0, 0, true, false, false, false,
>> handle_weak_attribute, NULL },
>> { "noplt", 0, 0, true, false, false, false,
>> @@ -2505,6 +2509,96 @@ handle_warn_if_not_aligned_attribute (tree *node,
>> tree name,
>> no_add_attrs, true);
>> }
>>
>> +/* Handle a "strict_flex_arrays" attribute; arguments as in
>> + struct attribute_spec.handler. */
>> +
>> +static tree
>> +handle_strict_flex_arrays_attribute (tree *node, tree name,
>> + tree args, int ARG_UNUSED (flags),
>> + bool *no_add_attrs)
>> +{
>> + tree decl = *node;
>> + tree argval = TREE_VALUE (args);
>> +
>> + /* This attribute only applies to field decls of a structure. */
>> + if (TREE_CODE (decl) != FIELD_DECL)
>> + {
>> + error_at (DECL_SOURCE_LOCATION (decl),
>> + "%qE attribute may not be specified for %q+D", name, decl);
>> + *no_add_attrs = true;
>> + }
>> + /* This attribute only applies to field with array type. */
>> + else if (TREE_CODE (TREE_TYPE (decl)) != ARRAY_TYPE)
>> + {
>> + error_at (DECL_SOURCE_LOCATION (decl),
>> + "%qE attribute may not be specified for a non array field",
>> + name);
>> + *no_add_attrs = true;
>> + }
>> + else if (TREE_CODE (argval) != INTEGER_CST)
>> + {
>> + error_at (DECL_SOURCE_LOCATION (decl),
>> + "%qE attribute argument not an integer", name);
>> + *no_add_attrs = true;
>> + }
>> + else if (!tree_fits_uhwi_p (argval) || tree_to_uhwi (argval) > 3)
>> + {
>> + error_at (DECL_SOURCE_LOCATION (decl),
>> + "%qE attribute argument %qE is not an integer constant"
>> + " between 0 and 3", name, argval);
>> + *no_add_attrs = true;
>> + }
>> + else
>> + {
>> + unsigned int level = tree_to_uhwi (argval);
>> + /* check whether the attribute is valid based on language standard.
>> + the attribute is only valid when flexible array member is
>> + supported in the language. Therefore, we should invalid this attribute
>> or
>> + specific level of this attribute for the following situations:
>> + A. When -std=c89 is specified, no language support at all, invalid this
>> + attribute and issue a warning;
>> + B. When -std=gnu89 is specified, only zero-length array extension and
>> + one-size array are supported, level=3 will be invalid and a warning
>> + will be issued.
>> + C. C++ without GNU extension, no language support at all, invalid this
>> + attribute and issue a warning;
>> + D. C++ with GNU extension, only zero-length array extension and one-size
>> + array are supported, level=3 will be invalid and a warning will be
>> + issued. */
>> + if (level > 0)
>> + {
>> + if (!c_dialect_cxx () && flag_iso && flag_isoc99 == 0)
>> + {
>> + warning (OPT_Wattributes, "%qE attribute ignored since it is "
>> + "not supported with a ISO C before C99", name);
>> + *no_add_attrs = true;
>> + }
>> + else if (!c_dialect_cxx () && !flag_iso
>> + && flag_isoc99 == 0 && level == 3)
>> + {
>> + warning (OPT_Wattributes, "%qE = 3 attribute ignored since it is "
>> + "not supported with a GNU extension GNU89", name);
>> + *no_add_attrs = true;
>> + }
>> + else if (c_dialect_cxx () && flag_iso)
>> + {
>> + warning (OPT_Wattributes, "%qE attribute ignored since it is "
>> + "not supported with a ISO C++", name);
>> + *no_add_attrs = true;
>> + }
>> + else if (c_dialect_cxx () && !flag_iso
>> + && level == 3)
>> + {
>> + warning (OPT_Wattributes, "%qE = 3 attribute ignored since it is "
>> + "not supported for C++ with GNU extension", name);
>> + *no_add_attrs = true;
>> + }
>> + }
>> + }
>> +
>> + return NULL_TREE;
>> +}
>> +
>> /* Handle a "weak" attribute; arguments as in
>> struct attribute_spec.handler. */
>>
>> diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
>> index 4e1463689de3..639eb40f3c86 100644
>> --- a/gcc/c-family/c-opts.cc
>> +++ b/gcc/c-family/c-opts.cc
>> @@ -870,6 +870,47 @@ c_common_post_options (const char **pfilename)
>> SET_OPTION_IF_UNSET (&global_options, &global_options_set,
>> flag_tree_loop_distribute_patterns, 0);
>>
>> + /* -fstrict-flex-arrays is only valid when flexible array member is
>> + supported in the language. Therefore, we should invalid this option or
>> + specific level of this option for the following situations:
>> + A. When -std=c89 is specified, no language support at all, invalid this
>> + option and issue a warning;
>> + B. When -std=gnu89 is specified, only zero-length array extension and
>> + one-size array are supported, level=3 will be invalid and a warning
>> + will be issued.
>> + C. C++ without GNU extension, no language support at all, invalid this
>> + option and issue a warning;
>> + D. C++ with GNU extension, only zero-length array extension and
>> one-size
>> + array are supported, level=3 will be invalid and a warning will be
>> + issued. */
>> + if (flag_strict_flex_arrays > 0)
>> + {
>> + if (!c_dialect_cxx () && flag_iso && flag_isoc99 == 0)
>> + {
>> + flag_strict_flex_arrays = 0;
>> + warning (0, "%<-fstrict-flex-arrays%> is not supported with a ISO C "
>> + "before C99, ignored");
>> + }
>> + else if (!c_dialect_cxx () && !flag_iso && flag_isoc99 == 0 &&
>> flag_strict_flex_arrays == 3)
>> + {
>> + flag_strict_flex_arrays = 0;
>> + warning (0, "%<-fstrict-flex-arrays=3%> is not supported with a "
>> + "GNU extension GNU89, ignored");
>> + }
>> + else if (c_dialect_cxx () && flag_iso)
>> + {
>> + flag_strict_flex_arrays = 0;
>> + warning (0, "%<-fstrict-flex-arrays%> is not supported with a ISO "
>> + "C++, ignored");
>> + }
>> + else if (c_dialect_cxx () && !flag_iso && flag_strict_flex_arrays ==
>> 3)
>> + {
>> + flag_strict_flex_arrays = 0;
>> + warning (0, "%<-fstrict-flex-arrays=3%> is not supported for C++ "
>> + "with GNU extension, ignored");
>> + }
>> + }
>> +
>> /* -Woverlength-strings is off by default, but is enabled by -Wpedantic.
>> It is never enabled in C++, as the minimum limit is not normative
>> in that standard. */
>> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>> index 44e1a60ce246..1e944f8a3055 100644
>> --- a/gcc/c-family/c.opt
>> +++ b/gcc/c-family/c.opt
>> @@ -2060,6 +2060,13 @@ fsized-deallocation
>> C++ ObjC++ Var(flag_sized_deallocation) Init(-1)
>> Enable C++14 sized deallocation support.
>>
>> +fstrict-flex-arrays
>> +C C++ Common Alias(fstrict-flex-arrays=,3,0)
>> +
>> +fstrict-flex-arrays=
>> +C C++ Common Joined RejectNegative UInteger Var(flag_strict_flex_arrays)
>> Init(0) IntegerRange(0,3)
>> +-fstrict-flex-arrays=<level> Treat the trailing array of a structure as
>> a flexible array in a stricter way. The default is treating all trailing
>> arrays of structures as flexible arrays.
>> +
>> fsquangle
>> C++ ObjC++ WarnRemoved
>>
>> diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
>> index ae8990c138fd..a2e125d4ddd5 100644
>> --- a/gcc/c/c-decl.cc
>> +++ b/gcc/c/c-decl.cc
>> @@ -4999,6 +4999,41 @@ set_array_declarator_inner (struct c_declarator *decl,
>> return decl;
>> }
>>
>> +/* Determine whether TYPE is a ISO C99 flexible array memeber type "[]". */
>> +static bool
>> +flexible_array_member_type_p (const_tree type)
>> +{
>> + if (TREE_CODE (type) == ARRAY_TYPE
>> + && TYPE_SIZE (type) == NULL_TREE
>> + && TYPE_DOMAIN (type) != NULL_TREE
>> + && TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL_TREE)
>> + return true;
>> +
>> + return false;
>> +}
>> +
>> +/* Determine whether TYPE is a one-element array type "[1]". */
>> +static bool
>> +one_element_array_type_p (const_tree type)
>> +{
>> + if (TREE_CODE (type) != ARRAY_TYPE)
>> + return false;
>> + return integer_zerop (array_type_nelts (type));
>> +}
>> +
>> +/* Determine whether TYPE is a zero-length array type "[0]". */
>> +static bool
>> +zero_length_array_type_p (const_tree type)
>> +{
>> + if (TREE_CODE (type) == ARRAY_TYPE)
>> + if (tree type_size = TYPE_SIZE_UNIT (type))
>> + if ((integer_zerop (type_size))
>> + && TYPE_DOMAIN (type) != NULL_TREE
>> + && TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL_TREE)
>> + return true;
>> + return false;
>> +}
>> +
>> /* INIT is a constructor that forms DECL's initializer. If the final
>> element initializes a flexible array field, add the size of that
>> initializer to DECL's size. */
>> @@ -5013,10 +5048,7 @@ add_flexible_array_elts_to_size (tree decl, tree init)
>>
>> elt = CONSTRUCTOR_ELTS (init)->last ().value;
>> type = TREE_TYPE (elt);
>> - if (TREE_CODE (type) == ARRAY_TYPE
>> - && TYPE_SIZE (type) == NULL_TREE
>> - && TYPE_DOMAIN (type) != NULL_TREE
>> - && TYPE_MAX_VALUE (TYPE_DOMAIN (type)) == NULL_TREE)
>> + if (flexible_array_member_type_p (type))
>> {
>> complete_array_type (&type, elt, false);
>> DECL_SIZE (decl)
>> @@ -8720,6 +8752,81 @@ finish_incomplete_vars (tree incomplete_vars, bool
>> toplevel)
>> }
>> }
>>
>> +
>> +/* Determine whether the FIELD_DECL X is a flexible array member according
>> to
>> + the following info:
>> + A. whether the FIELD_DECL X is the last field of the DECL_CONTEXT;
>> + B. whether the FIELD_DECL is an array that is declared as "[]", "[0]",
>> + or "[1]";
>> + C. flag_strict_flex_arrays;
>> + D. the attribute strict_flex_array that is attached to the field
>> + if presenting.
>> + Return TRUE when it's a flexible array member, FALSE otherwise. */
>> +
>> +static bool
>> +is_flexible_array_member_p (bool is_last_field,
>> + tree x)
>> +{
>> + /* if not the last field, return false. */
>> + if (!is_last_field)
>> + return false;
>> +
>> + /* if not an array field, return false. */
>> + if (TREE_CODE (TREE_TYPE (x)) != ARRAY_TYPE)
>> + return false;
>> +
>> + bool is_zero_length_array = zero_length_array_type_p (TREE_TYPE (x));
>> + bool is_one_element_array = one_element_array_type_p (TREE_TYPE (x));
>> + bool is_flexible_array = flexible_array_member_type_p (TREE_TYPE (x));
>> +
>> + unsigned int strict_flex_array_level = flag_strict_flex_arrays;
>> +
>> + tree attr_strict_flex_array = lookup_attribute ("strict_flex_arrays",
>> + DECL_ATTRIBUTES (x));
>> + /* if there is a strict_flex_array attribute attached to the field,
>> + override the flag_strict_flex_arrays. */
>> + if (attr_strict_flex_array)
>> + {
>> + /* get the value of the level first from the attribute. */
>> + unsigned HOST_WIDE_INT attr_strict_flex_array_level = 0;
>> + gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
>> + attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
>> + gcc_assert (TREE_VALUE (attr_strict_flex_array) != NULL_TREE);
>> + attr_strict_flex_array = TREE_VALUE (attr_strict_flex_array);
>> + gcc_assert (tree_fits_uhwi_p (attr_strict_flex_array));
>> + attr_strict_flex_array_level = tree_to_uhwi (attr_strict_flex_array);
>> +
>> + /* the attribute has higher priority than flag_struct_flex_array. */
>> + strict_flex_array_level = attr_strict_flex_array_level;
>> + }
>> +
>> + switch (strict_flex_array_level)
>> + {
>> + case 0:
>> + /* default, all trailing arrays are flexiable array members. */
>> + return true;
>> + case 1:
>> + /* Level 1: all "[1]", "[0]", and "[]" are flexiable array members. */
>> + if (is_one_element_array)
>> + return true;
>> + /* FALLTHROUGH. */
>> + case 2:
>> + /* Level 2: all "[0]", and "[]" are flexiable array members. */
>> + if (is_zero_length_array)
>> + return true;
>> + /* FALLTHROUGH. */
>> + case 3:
>> + /* Level 3: Only "[]" are flexible array members. */
>> + if (is_flexible_array)
>> + return true;
>> + break;
>> + default:
>> + gcc_unreachable ();
>> + }
>> + return false;
>> +}
>> +
>> +
>> /* Fill in the fields of a RECORD_TYPE or UNION_TYPE node, T.
>> LOC is the location of the RECORD_TYPE or UNION_TYPE's definition.
>> FIELDLIST is a chain of FIELD_DECL nodes for the fields.
>> @@ -8781,6 +8888,11 @@ finish_struct (location_t loc, tree t, tree
>> fieldlist, tree attributes,
>> bool saw_named_field = false;
>> for (x = fieldlist; x; x = DECL_CHAIN (x))
>> {
>> + /* whether this field is the last field of the structure or union.
>> + for UNION, any field is the last field of it. */
>> + bool is_last_field = (DECL_CHAIN (x) == NULL_TREE)
>> + || (TREE_CODE (t) == UNION_TYPE);
>> +
>> if (TREE_TYPE (x) == error_mark_node)
>> continue;
>>
>> @@ -8819,10 +8931,7 @@ finish_struct (location_t loc, tree t, tree
>> fieldlist, tree attributes,
>> DECL_PACKED (x) = 1;
>>
>> /* Detect flexible array member in an invalid context. */
>> - if (TREE_CODE (TREE_TYPE (x)) == ARRAY_TYPE
>> - && TYPE_SIZE (TREE_TYPE (x)) == NULL_TREE
>> - && TYPE_DOMAIN (TREE_TYPE (x)) != NULL_TREE
>> - && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (x))) == NULL_TREE)
>> + if (flexible_array_member_type_p (TREE_TYPE (x)))
>> {
>> if (TREE_CODE (t) == UNION_TYPE)
>> {
>> @@ -8830,7 +8939,7 @@ finish_struct (location_t loc, tree t, tree fieldlist,
>> tree attributes,
>> "flexible array member in union");
>> TREE_TYPE (x) = error_mark_node;
>> }
>> - else if (DECL_CHAIN (x) != NULL_TREE)
>> + else if (!is_last_field)
>> {
>> error_at (DECL_SOURCE_LOCATION (x),
>> "flexible array member not at end of struct");
>> @@ -8850,6 +8959,9 @@ finish_struct (location_t loc, tree t, tree fieldlist,
>> tree attributes,
>> pedwarn (DECL_SOURCE_LOCATION (x), OPT_Wpedantic,
>> "invalid use of structure with flexible array member");
>>
>> + /* Set DECL_NOT_FLEXARRAY flag for FIELD_DECL x. */
>> + DECL_NOT_FLEXARRAY (x) = !is_flexible_array_member_p (is_last_field,
>> x);
>> +
>> if (DECL_NAME (x)
>> || RECORD_OR_UNION_TYPE_P (TREE_TYPE (x)))
>> saw_named_field = true;
>> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
>> index f27f4d091e5e..75ee2514f66b 100644
>> --- a/gcc/cp/module.cc
>> +++ b/gcc/cp/module.cc
>> @@ -5414,6 +5414,7 @@ trees_out::core_bools (tree t)
>> WB (t->decl_common.decl_by_reference_flag);
>> WB (t->decl_common.decl_read_flag);
>> WB (t->decl_common.decl_nonshareable_flag);
>> + WB (t->decl_common.decl_not_flexarray);
>> }
>>
>> if (CODE_CONTAINS_STRUCT (code, TS_DECL_WITH_VIS))
>> @@ -5558,6 +5559,7 @@ trees_in::core_bools (tree t)
>> RB (t->decl_common.decl_by_reference_flag);
>> RB (t->decl_common.decl_read_flag);
>> RB (t->decl_common.decl_nonshareable_flag);
>> + RB (t->decl_common.decl_not_flexarray);
>> }
>>
>> if (CODE_CONTAINS_STRUCT (code, TS_DECL_WITH_VIS))
>> diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
>> index 7fe7f8817cdd..99b43ed3852c 100644
>> --- a/gcc/doc/extend.texi
>> +++ b/gcc/doc/extend.texi
>> @@ -7473,6 +7473,39 @@ This warning can be disabled by
>> @option{-Wno-if-not-aligned}.
>> The @code{warn_if_not_aligned} attribute can also be used for types
>> (@pxref{Common Type Attributes}.)
>>
>> +@cindex @code{strict_flex_arrays} variable attribute
>> +@item strict_flex_arrays (@var{level})
>> +The @code{strict_flex_arrays} attribute should be attached to the trailing
>> +array field of a structure. It specifies the level of strictness of
>> +treating the trailing array field of a structure as a flexible array
>> +member. @var{level} must be an integer betwen 0 to 3.
>> +
>> +@var{level}=0 is the least strict level, all trailing arrays of structures
>> +are treated as flexible array members. @var{level}=3 is the strictest level,
>> +only when the trailing array is declared as a flexible array member per C99
>> +standard onwards ([]), it is treated as a flexible array member.
>> +
>> +There are two more levels in between 0 and 3, which are provided to support
>> +older codes that use GCC zero-length array extension ([0]) or one-size array
>> +as flexible array member ([1]):
>> +When @var{level} is 1, the trailing array is treated as a flexible array
>> member
>> +when it is declared as either "[]", "[0]", or "[1]";
>> +When @var{level} is 2, the trailing array is treated as a flexible array
>> member
>> +when it is declared as either "[]", or "[0]".
>> +
>> +This attribute can be used with or without the
>> @option{-fstrict-flex-arrays}.
>> +When both the attribute and the option present at the same time, the level
>> of
>> +the strictness for the specific trailing array field is determined by the
>> +attribute.
>> +
>> +This attribute is only valid when flexible array member is supported in the
>> +language. For ISO C before C99 and ISO C++, no language support for the
>> flexible
>> +array member at all, this attribute will be invalid and a warning is issued.
>> +When -std=gnu89 is specified or C++ with GNU extension, only zero-length
>> array
>> +extension and one-size array are supported, as a result, @var{level}=3 will
>> be
>> +invalid and a warning is issued.
>> +
>> +
>> @item alloc_size (@var{position})
>> @itemx alloc_size (@var{position-1}, @var{position-2})
>> @cindex @code{alloc_size} variable attribute
>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index 863580b3710a..2a0a3cf3de10 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -207,7 +207,8 @@ in the following sections.
>> -fopenmp -fopenmp-simd @gol
>> -fpermitted-flt-eval-methods=@var{standard} @gol
>> -fplan9-extensions -fsigned-bitfields -funsigned-bitfields @gol
>> --fsigned-char -funsigned-char -fsso-struct=@var{endianness}}
>> +-fsigned-char -funsigned-char -fstrict-flex-arrays[=@var{n}] @gol
>> +-fsso-struct=@var{endianness}}
>>
>> @item C++ Language Options
>> @xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
>> @@ -2826,6 +2827,37 @@ The type @code{char} is always a distinct type from
>> each of
>> @code{signed char} or @code{unsigned char}, even though its behavior
>> is always just like one of those two.
>>
>> +@item -fstrict-flex-arrays
>> +@opindex fstrict-flex-arrays
>> +@opindex fno-strict-flex-arrays
>> +Treat the trailing array of a structure as a flexible array member in a
>> +stricter way.
>> +The positive form is equivalent to @option{-fstrict-flex-arrays=3}, which
>> is the
>> +strictest. A trailing array is treated as a flexible array member only
>> when it
>> +is declared as a flexible array member per C99 standard onwards.
>> +The negative form is equivalent to @option{-fstrict-flex-arrays=0}, which
>> is the
>> +least strict. All trailing arrays of structures are treated as flexible
>> array
>> +members.
>> +
>> +@item -fstrict-flex-arrays=@var{level}
>> +@opindex fstrict-flex-arrays=@var{level}
>> +Treat the trailing array of a structure as a flexible array member in a
>> +stricter way. The value of @var{level} controls the level of strictness.
>> +
>> +The possible values of @var{level} are the same as for the
>> +@code{strict_flex_array} attribute (@pxref{Variable Attributes}).
>> +
>> +You can control this behavior for a specific trailing array field of a
>> +structure by using the variable attribute @code{strict_flex_array} attribute
>> +(@pxref{Variable Attributes}).
>> +
>> +This option is only valid when flexible array member is supported in the
>> +language. FOR ISO C before C99 and ISO C++, no language support for the
>> flexible
>> +array member at all, this option will be invalid and a warning will be
>> issued.
>> +When -std=gnu89 is specified or C++ with GNU extension, only zero-length
>> array
>> +extension and one-size array are supported, as a result, @var{level}=3 will
>> be
>> +invalid and a warning will be issued.
>> +
>> @item -fsso-struct=@var{endianness}
>> @opindex fsso-struct
>> Set the default scalar storage order of structures and unions to the
>> diff --git a/gcc/print-tree.cc b/gcc/print-tree.cc
>> index 6d45a4a59669..58a98250cc4f 100644
>> --- a/gcc/print-tree.cc
>> +++ b/gcc/print-tree.cc
>> @@ -517,8 +517,12 @@ print_node (FILE *file, const char *prefix, tree node,
>> int indent,
>> fprintf (file, " align:%d warn_if_not_align:%d",
>> DECL_ALIGN (node), DECL_WARN_IF_NOT_ALIGN (node));
>> if (code == FIELD_DECL)
>> - fprintf (file, " offset_align " HOST_WIDE_INT_PRINT_UNSIGNED,
>> - DECL_OFFSET_ALIGN (node));
>> + {
>> + fprintf (file, " offset_align " HOST_WIDE_INT_PRINT_UNSIGNED,
>> + DECL_OFFSET_ALIGN (node));
>> + fprintf (file, " decl_not_flexarray: %d",
>> + DECL_NOT_FLEXARRAY (node));
>> + }
>>
>> if (code == FUNCTION_DECL && fndecl_built_in_p (node))
>> {
>> diff --git a/gcc/testsuite/g++.dg/strict-flex-array-1.C
>> b/gcc/testsuite/g++.dg/strict-flex-array-1.C
>> new file mode 100644
>> index 000000000000..47adaf7bac4a
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/strict-flex-array-1.C
>> @@ -0,0 +1,31 @@
>> +/* testing the correct usage of attribute strict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2" } */
>> +
>> +
>> +int x __attribute__ ((strict_flex_arrays (1))); /* { dg-error
>> "'strict_flex_arrays' attribute may not be specified for 'x'" } */
>> +
>> +struct trailing {
>> + int a;
>> + int c __attribute ((strict_flex_arrays)); /* { dg-error "wrong number
>> of arguments specified for 'strict_flex_arrays' attribute" } */
>> +};
>> +
>> +struct trailing_1 {
>> + int a;
>> + int b;
>> + int c __attribute ((strict_flex_arrays (2))); /* { dg-error
>> "'strict_flex_arrays' attribute may not be specified for a non array field"
>> } */
>> +};
>> +
>> +extern int d;
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1] __attribute ((strict_flex_arrays (d))); /* { dg-error
>> "'strict_flex_arrays' attribute argument not an integer" } */
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (5))); /* { dg-error
>> "'strict_flex_arrays' attribute argument '5' is not an integer constant
>> between 0 and 3" } */
>> +};
>> diff --git a/gcc/testsuite/g++.dg/strict-flex-array-2.C
>> b/gcc/testsuite/g++.dg/strict-flex-array-2.C
>> new file mode 100644
>> index 000000000000..245f8fe0bc73
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/strict-flex-array-2.C
>> @@ -0,0 +1,16 @@
>> +/* testing the correct usage of flag -fstrict_flex_array for C++. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays -std=c++98" } */
>> +
>> +struct trailing_array {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (3))); /* { dg-warning
>> "attribute ignored since it is not supported with a ISO C\\+\\+" } */
>> +};
>> +
>> +int foo(int a)
>> +{
>> + return 0;
>> +}
>> +
>> +/* { dg-warning "is not supported with a ISO C\\+\\+, ignored" "" { target
>> *-*-* } 0 } */
>> diff --git a/gcc/testsuite/g++.dg/strict-flex-array-3.C
>> b/gcc/testsuite/g++.dg/strict-flex-array-3.C
>> new file mode 100644
>> index 000000000000..2a733a5bccf4
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/strict-flex-array-3.C
>> @@ -0,0 +1,21 @@
>> +/* testing the correct usage of flag -fstrict_flex_array for C++. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays -std=gnu++98" } */
>> +/* { dg-warning "'-fstrict-flex-arrays=3' is not supported for C\\+\\+ with
>> GNU extension, ignored" "" { target *-*-* } 0 } */
>> +
>> +struct trailing_array {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (3))); /* { dg-warning
>> "'strict_flex_arrays' = 3 attribute ignored since it is not supported for
>> C\\+\\+ with GNU extension" } */
>> +};
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (2))); /* { dg-bogus
>> "'strict_flex_arrays' = 3 attribute ignored since it is not supported for
>> C\\+\\+ with GNU extension" } */
>> +};
>> +
>> +int foo(int a)
>> +{
>> + return a + 2;
>> +}
>> diff --git a/gcc/testsuite/g++.dg/strict-flex-array-4.C
>> b/gcc/testsuite/g++.dg/strict-flex-array-4.C
>> new file mode 100644
>> index 000000000000..804e4cf459ef
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/strict-flex-array-4.C
>> @@ -0,0 +1,9 @@
>> +/* testing the correct usage of flag -fstrict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays=2 -std=gnu++98" } */
>> +/* { dg-bogus "is not supported for C\\+\\+ with GNU extension, ignored" ""
>> { target *-*-* } 0 } */
>> +
>> +int foo(int a)
>> +{
>> + return a + 2;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-1.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-1.c
>> new file mode 100644
>> index 000000000000..47adaf7bac4a
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-1.c
>> @@ -0,0 +1,31 @@
>> +/* testing the correct usage of attribute strict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2" } */
>> +
>> +
>> +int x __attribute__ ((strict_flex_arrays (1))); /* { dg-error
>> "'strict_flex_arrays' attribute may not be specified for 'x'" } */
>> +
>> +struct trailing {
>> + int a;
>> + int c __attribute ((strict_flex_arrays)); /* { dg-error "wrong number
>> of arguments specified for 'strict_flex_arrays' attribute" } */
>> +};
>> +
>> +struct trailing_1 {
>> + int a;
>> + int b;
>> + int c __attribute ((strict_flex_arrays (2))); /* { dg-error
>> "'strict_flex_arrays' attribute may not be specified for a non array field"
>> } */
>> +};
>> +
>> +extern int d;
>> +
>> +struct trailing_array_2 {
>> + int a;
>> + int b;
>> + int c[1] __attribute ((strict_flex_arrays (d))); /* { dg-error
>> "'strict_flex_arrays' attribute argument not an integer" } */
>> +};
>> +
>> +struct trailing_array_3 {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (5))); /* { dg-error
>> "'strict_flex_arrays' attribute argument '5' is not an integer constant
>> between 0 and 3" } */
>> +};
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> new file mode 100644
>> index 000000000000..967a240040dc
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-2.c
>> @@ -0,0 +1,15 @@
>> +/* testing the correct usage of flag -fstrict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays -std=c89" } */
>> +/* { dg-warning "'-fstrict-flex-arrays' is not supported with a ISO C
>> before C99, ignored" "" { target *-*-* } 0 } */
>> +
>> +struct trailing_array {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (3))); /* { dg-warning
>> "'strict_flex_arrays' attribute ignored since it is not supported with a ISO
>> C before C99" } */
>> +};
>> +
>> +int foo(int a)
>> +{
>> + return a + 2;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> new file mode 100644
>> index 000000000000..879de7f203c8
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-3.c
>> @@ -0,0 +1,21 @@
>> +/* testing the correct usage of flag -fstrict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays -std=gnu89" } */
>> +/* { dg-warning "'-fstrict-flex-arrays=3' is not supported with a GNU
>> extension GNU89, ignored" "" { target *-*-* } 0 } */
>> +
>> +struct trailing_array {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (3))); /* { dg-warning
>> "'strict_flex_arrays' = 3 attribute ignored since it is not supported with a
>> GNU extension GNU89" } */
>> +};
>> +
>> +struct trailing_array_1 {
>> + int a;
>> + int b;
>> + int c[0] __attribute ((strict_flex_arrays (2))); /* { dg-bogus
>> "'strict_flex_arrays' = 3 attribute ignored since it is not supported with a
>> GNU extension GNU89" } */
>> +};
>> +
>> +int foo(int a)
>> +{
>> + return a + 2;
>> +}
>> diff --git a/gcc/testsuite/gcc.dg/strict-flex-array-4.c
>> b/gcc/testsuite/gcc.dg/strict-flex-array-4.c
>> new file mode 100644
>> index 000000000000..ce64c24db301
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/strict-flex-array-4.c
>> @@ -0,0 +1,10 @@
>> +/* testing the correct usage of flag -fstrict_flex_array. */
>> +/* { dg-do compile } */
>> +/* { dg-options "-O2 -fstrict-flex-arrays=2 -std=gnu89" } */
>> +/* { dg-bogus "is not supported with a GNU extension GNU89, ignored" "" {
>> target *-*-* } 0 } */
>> +
>> +
>> +int foo(int a)
>> +{
>> + return a + 2;
>> +}
>> diff --git a/gcc/tree-core.h b/gcc/tree-core.h
>> index 86a07c282af2..f822cb539dd0 100644
>> --- a/gcc/tree-core.h
>> +++ b/gcc/tree-core.h
>> @@ -1813,7 +1813,10 @@ struct GTY(()) tree_decl_common {
>> TYPE_WARN_IF_NOT_ALIGN. */
>> unsigned int warn_if_not_align : 6;
>>
>> - /* 14 bits unused. */
>> + /* In FIELD_DECL, this is DECL_NOT_FLEXARRAY. */
>> + unsigned int decl_not_flexarray : 1;
>> +
>> + /* 13 bits unused. */
>>
>> /* UID for points-to sets, stable over copying from inlining. */
>> unsigned int pt_uid;
>> diff --git a/gcc/tree-streamer-in.cc b/gcc/tree-streamer-in.cc
>> index 196f19c759f2..21e6e8eb1c0a 100644
>> --- a/gcc/tree-streamer-in.cc
>> +++ b/gcc/tree-streamer-in.cc
>> @@ -261,6 +261,7 @@ unpack_ts_decl_common_value_fields (struct bitpack_d
>> *bp, tree expr)
>> else
>> SET_DECL_FIELD_ABI_IGNORED (expr, val);
>> expr->decl_common.off_align = bp_unpack_value (bp, 8);
>> + DECL_NOT_FLEXARRAY (expr) = (unsigned) bp_unpack_value (bp, 1);
>> }
>>
>> else if (VAR_P (expr))
>> diff --git a/gcc/tree-streamer-out.cc b/gcc/tree-streamer-out.cc
>> index d39dc158a465..68e40dbdb8f2 100644
>> --- a/gcc/tree-streamer-out.cc
>> +++ b/gcc/tree-streamer-out.cc
>> @@ -229,6 +229,7 @@ pack_ts_decl_common_value_fields (struct bitpack_d *bp,
>> tree expr)
>> else
>> bp_pack_value (bp, DECL_FIELD_ABI_IGNORED (expr), 1);
>> bp_pack_value (bp, expr->decl_common.off_align, 8);
>> + bp_pack_value (bp, DECL_NOT_FLEXARRAY (expr), 1);
>> }
>>
>> else if (VAR_P (expr))
>> diff --git a/gcc/tree.cc b/gcc/tree.cc
>> index fed1434d141d..d698e8c9c213 100644
>> --- a/gcc/tree.cc
>> +++ b/gcc/tree.cc
>> @@ -12678,14 +12678,30 @@ array_ref_up_bound (tree exp)
>> }
>>
>> /* Returns true if REF is an array reference, component reference,
>> - or memory reference to an array at the end of a structure.
>> - If this is the case, the array may be allocated larger
>> - than its upper bound implies. */
>> + or memory reference to an array whose actual size might be larger
>> + than its upper bound implies, there are multiple cases:
>> + A. a ref to a flexible array member at the end of a structure;
>> + B. a ref to an array with a different type against the original decl;
>> + for example:
>>
>> + short a[16] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
>> };
>> + (*((char(*)[16])&a[0]))[i+8]
>> +
>> + C. a ref to an array that was passed as a parameter;
>> + for example:
>> +
>> + int test (uint8_t *p, uint32_t t[1][1], int n) {
>> + for (int i = 0; i < 4; i++, p++)
>> + t[i][0] = ...;
>> +
>> + FIXME, the name of this routine need to be changed to be more accurate.
>> */
>> bool
>> array_at_struct_end_p (tree ref)
>> {
>> - tree atype;
>> + /* the TYPE for this array referece. */
>> + tree atype = NULL_TREE;
>> + /* the FIELD_DECL for the array field in the containing structure. */
>> + tree afield_decl = NULL_TREE;
>>
>> if (TREE_CODE (ref) == ARRAY_REF
>> || TREE_CODE (ref) == ARRAY_RANGE_REF)
>> @@ -12695,7 +12711,10 @@ array_at_struct_end_p (tree ref)
>> }
>> else if (TREE_CODE (ref) == COMPONENT_REF
>> && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 1))) == ARRAY_TYPE)
>> - atype = TREE_TYPE (TREE_OPERAND (ref, 1));
>> + {
>> + atype = TREE_TYPE (TREE_OPERAND (ref, 1));
>> + afield_decl = TREE_OPERAND (ref, 1);
>> + }
>> else if (TREE_CODE (ref) == MEM_REF)
>> {
>> tree arg = TREE_OPERAND (ref, 0);
>> @@ -12707,6 +12726,7 @@ array_at_struct_end_p (tree ref)
>> if (tree fld = last_field (argtype))
>> {
>> atype = TREE_TYPE (fld);
>> + afield_decl = fld;
>> if (TREE_CODE (atype) != ARRAY_TYPE)
>> return false;
>> if (VAR_P (arg) && DECL_SIZE (fld))
>> @@ -12760,13 +12780,16 @@ array_at_struct_end_p (tree ref)
>> ref = TREE_OPERAND (ref, 0);
>> }
>>
>> - /* The array now is at struct end. Treat flexible arrays as
>> + gcc_assert (!afield_decl
>> + || (afield_decl && TREE_CODE (afield_decl) == FIELD_DECL));
>> +
>> + /* The array now is at struct end. Treat flexible array member as
>> always subject to extend, even into just padding constrained by
>> an underlying decl. */
>> if (! TYPE_SIZE (atype)
>> || ! TYPE_DOMAIN (atype)
>> || ! TYPE_MAX_VALUE (TYPE_DOMAIN (atype)))
>> - return true;
>> + return afield_decl ? !DECL_NOT_FLEXARRAY (afield_decl) : true;
>>
>> /* If the reference is based on a declared entity, the size of the array
>> is constrained by its given domain. (Do not trust commons PR/69368).
>> */
>> @@ -12788,9 +12811,9 @@ array_at_struct_end_p (tree ref)
>> if (TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (atype))) != INTEGER_CST
>> || TREE_CODE (TYPE_MAX_VALUE (TYPE_DOMAIN (atype))) != INTEGER_CST
>> || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (atype))) != INTEGER_CST)
>> - return true;
>> + return afield_decl ? !DECL_NOT_FLEXARRAY (afield_decl) : true;
>> if (! get_addr_base_and_unit_offset (ref_to_array, &offset))
>> - return true;
>> + return afield_decl ? !DECL_NOT_FLEXARRAY (afield_decl) : true;
>>
>> /* If at least one extra element fits it is a flexarray. */
>> if (known_le ((wi::to_offset (TYPE_MAX_VALUE (TYPE_DOMAIN (atype)))
>> @@ -12798,12 +12821,12 @@ array_at_struct_end_p (tree ref)
>> + 2)
>> * wi::to_offset (TYPE_SIZE_UNIT (TREE_TYPE (atype))),
>> wi::to_offset (DECL_SIZE_UNIT (ref)) - offset))
>> - return true;
>> + return afield_decl ? !DECL_NOT_FLEXARRAY (afield_decl) : true;
>>
>> return false;
>> }
>>
>> - return true;
>> + return afield_decl ? !DECL_NOT_FLEXARRAY (afield_decl) : true;
>> }
>>
>> /* Return a tree representing the offset, in bytes, of the field referenced
>> diff --git a/gcc/tree.h b/gcc/tree.h
>> index e6564aaccb7b..f911c0a46e69 100644
>> --- a/gcc/tree.h
>> +++ b/gcc/tree.h
>> @@ -2993,6 +2993,12 @@ extern void decl_value_expr_insert (tree, tree);
>> #define DECL_PADDING_P(NODE) \
>> (FIELD_DECL_CHECK (NODE)->decl_common.decl_flag_3)
>>
>> +/* Used in a FIELD_DECL to indicate whether this field is not a flexible
>> + array member. This is only valid for the last array type field of a
>> + structure. */
>> +#define DECL_NOT_FLEXARRAY(NODE) \
>> + (FIELD_DECL_CHECK (NODE)->decl_common.decl_not_flexarray)
>> +
>> /* A numeric unique identifier for a LABEL_DECL. The UID allocation is
>> dense, unique within any one function, and may be used to index arrays.
>> If the value is -1, then no UID has been assigned. */
>> @@ -5531,10 +5537,10 @@ extern tree component_ref_field_offset (tree);
>> 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. */
>> + 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
>>
>
> --
> 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)
