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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
end of thread, other threads:[~2023-06-29 17:16 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [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
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