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Thread-Topic: [PATCH 2/2] Documentation Update. 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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: CH2PR10MB4344.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: f6ecabfc-c518-4153-2261-08db04894de0 X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Feb 2023 19:19:56.6154 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: nmIXcnQpH1O9oM4T2atOMG1eEGv107aYjKI0k6wKjRImEVElIMw/p6sZ1yNXqFp2iP1W5tfLUFqm5Xs6gurMug== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR10MB6541 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-02-01_04,2023-01-31_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 malwarescore=0 adultscore=0 bulkscore=0 mlxscore=0 mlxlogscore=891 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302010164 X-Proofpoint-GUID: F2W_PRikRG3F03e3AOQ__HlTjV4toUHd X-Proofpoint-ORIG-GUID: F2W_PRikRG3F03e3AOQ__HlTjV4toUHd X-Spam-Status: No, score=-5.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: > On Feb 1, 2023, at 1:57 PM, Siddhesh Poyarekar wrot= e: >=20 > On 2023-02-01 13:24, Qing Zhao wrote: >>> On Feb 1, 2023, at 11:55 AM, Siddhesh Poyarekar w= rote: >>>=20 >>> On 2023-01-31 09:11, Qing Zhao wrote: >>>> Update documentation to clarify a GCC extension on structure with >>>> flexible array member being nested in another structure. >>>> gcc/ChangeLog: >>>> * doc/extend.texi: Document GCC extension on a structure containing >>>> a flexible array member to be a member of another structure. >>>=20 >>> Should this resolve pr#77650 since the proposed action there appears to= be to document these semantics? >> My understanding of pr77650 is specifically for documentation on the fol= lowing case: >> The structure with a flexible array member is the middle field of anothe= r structure. >> Which I added in the documentation as the 2nd situation. >> However, I am still not very comfortable on my current clarification on = this situation: how should we document on >> the expected gcc behavior to handle such situation? >=20 > I reckon wording that dissuades programmers from using this might be appr= opriate, i.e. don't rely on this and if you already have such nested flex a= rrays, change code to remove them. Good suggestion.=20 >=20 >>>> +In the above, @code{flex_data.data[]} is allowed to be extended flexi= bly to >>>> +the padding. E.g, up to 4 elements. >=20 > """ > ... Relying on space in struct padding is bad programming practice and an= y code relying on this behaviour should be modified to ensure that flexible= array members only end up at the ends of arrays. The `-pedantic` flag sho= uld help identify such uses. > """ >=20 > Although -pedantic will also flag on flex arrays nested in structs even i= f they're at the end of the parent struct, so my suggestion on the warning = is not really perfect. Yes, both the situations (flex arrays nested in the end of of structures, o= r flex array nested in the middle of structures) are NOT standard-conformin= g, we might need to dis-encourage both situations? Qing >=20 > Sid