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* [Bug c/77650] struct with a nested flexible array followed by another member accepted
[not found] <bug-77650-4@http.gcc.gnu.org/bugzilla/>
@ 2022-12-02 16:36 ` siddhesh at gcc dot gnu.org
2023-06-12 15:51 ` qinzhao at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 4+ messages in thread
From: siddhesh at gcc dot gnu.org @ 2022-12-02 16:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77650
Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |siddhesh at gcc dot gnu.org
--- Comment #6 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> ---
*** Bug 107951 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/77650] struct with a nested flexible array followed by another member accepted
[not found] <bug-77650-4@http.gcc.gnu.org/bugzilla/>
2022-12-02 16:36 ` [Bug c/77650] struct with a nested flexible array followed by another member accepted siddhesh at gcc dot gnu.org
@ 2023-06-12 15:51 ` qinzhao at gcc dot gnu.org
2023-06-27 14:25 ` qinzhao at gcc dot gnu.org
2023-06-29 17:16 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: qinzhao at gcc dot gnu.org @ 2023-06-12 15:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77650
--- Comment #7 from qinzhao at gcc dot gnu.org ---
the patch for this documentation change in GCC has been posted and approved
at:https://gcc.gnu.org/pipermail/gcc-patches/2023-May/620148.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/77650] struct with a nested flexible array followed by another member accepted
[not found] <bug-77650-4@http.gcc.gnu.org/bugzilla/>
2022-12-02 16:36 ` [Bug c/77650] struct with a nested flexible array followed by another member accepted siddhesh at gcc dot gnu.org
2023-06-12 15:51 ` qinzhao at gcc dot gnu.org
@ 2023-06-27 14:25 ` qinzhao at gcc dot gnu.org
2023-06-29 17:16 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: qinzhao at gcc dot gnu.org @ 2023-06-27 14:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77650
--- Comment #8 from qinzhao at gcc dot gnu.org ---
for record purpose, the code in glibc has already been fixed.
https://gcc.gnu.org/pipermail/gcc-patches/2023-February/611220.html
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c/77650] struct with a nested flexible array followed by another member accepted
[not found] <bug-77650-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2023-06-27 14:25 ` qinzhao at gcc dot gnu.org
@ 2023-06-29 17:16 ` cvs-commit at gcc dot gnu.org
3 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2023-06-29 17:16 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77650
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Qing Zhao <qinzhao@gcc.gnu.org>:
https://gcc.gnu.org/g:070a6bf0bdc6761ad77ac97404c98f00a7007d54
commit r14-2197-g070a6bf0bdc6761ad77ac97404c98f00a7007d54
Author: Qing Zhao <qing.zhao@oracle.com>
Date: Thu Jun 29 17:07:26 2023 +0000
Update documentation to clarify a GCC extension [PR c/77650]
on a structure with a C99 flexible array member being nested in
another structure.
"The GCC extension accepts a structure containing an ISO C99 "flexible
array
member", or a union containing such a structure (possibly recursively)
to be a member of a structure.
There are two situations:
* A structure containing a C99 flexible array member, or a union
containing such a structure, is the last field of another structure,
for example:
struct flex { int length; char data[]; };
union union_flex { int others; struct flex f; };
struct out_flex_struct { int m; struct flex flex_data; };
struct out_flex_union { int n; union union_flex flex_data; };
In the above, both 'out_flex_struct.flex_data.data[]' and
'out_flex_union.flex_data.f.data[]' are considered as flexible
arrays too.
* A structure containing a C99 flexible array member, or a union
containing such a structure, is not the last field of another
structure,
for example:
struct flex { int length; char data[]; };
struct mid_flex { int m; struct flex flex_data; int n; };
In the above, accessing a member of the array
'mid_flex.flex_data.data[]'
might have undefined behavior. Compilers do not handle such a case
consistently, Any code relying on this case should be modified to
ensure
that flexible array members only end up at the ends of structures.
Please use the warning option '-Wflex-array-member-not-at-end' to
identify all such cases in the source code and modify them. This
extension
is now deprecated.
"
PR c/77650
gcc/c-family/ChangeLog:
* c.opt: New option -Wflex-array-member-not-at-end.
gcc/c/ChangeLog:
* c-decl.cc (finish_struct): Issue warnings for new option.
gcc/ChangeLog:
* doc/extend.texi: Document GCC extension on a structure containing
a flexible array member to be a member of another structure.
gcc/testsuite/ChangeLog:
* gcc.dg/variable-sized-type-flex-array.c: New test.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-12-02 16:36 ` [Bug c/77650] struct with a nested flexible array followed by another member accepted siddhesh at gcc dot gnu.org
2023-06-12 15:51 ` qinzhao at gcc dot gnu.org
2023-06-27 14:25 ` qinzhao at gcc dot gnu.org
2023-06-29 17:16 ` cvs-commit at gcc dot gnu.org
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