From: Phillip Wood <phillip.wood123@gmail•com>
To: Ezekiel Newren <ezekielnewren@gmail•com>, phillip.wood@dunelm•org.uk
Cc: Ezekiel Newren via GitGitGadget <gitgitgadget@gmail•com>,
git@vger•kernel.org, Elijah Newren <newren@gmail•com>,
"brian m. carlson" <sandals@crustytoothpaste•net>,
Taylor Blau <me@ttaylorr•com>
Subject: Re: [PATCH 4/7] xdiff: make fields of xrecord_t Rust friendly
Date: Thu, 31 Jul 2025 15:20:44 +0100 [thread overview]
Message-ID: <ad453eee-23cd-42fe-97bd-1ff0fc2f3edf@gmail.com> (raw)
In-Reply-To: <CAH=ZcbALsQqTrvNJ4ZKmVWc6PHtTA+8k8p6_D=x=BfMXxnayfA@mail.gmail.com>
On 28/07/2025 21:14, Ezekiel Newren wrote:
> On Mon, Jul 28, 2025 at 1:52 PM Phillip Wood <phillip.wood123@gmail•com> wrote:
>
> Ah, I misunderstood the scope of your question. I could not fit an
> example of why this design pattern made sense into this patch series,
> so I'll explain with an example here:
>
> If C defines a struct like below then it's obvious how to translate
> that into rust for ffi purposes. It also makes it clear that this C
> struct is expressly for the purpose of C <-> Rust interoperability.
> struct some_struct {
> u8* ptr;
> usize length;
> u64 counter;
> };
>
> This is how that C struct needs to be defined in Rust so that it can
> interoperate with C, and making C use the Rust types reduces the
> chance of copy paste, and primitive type definition mismatch errors.
> #[repr(C)]
> pub struct some_struct {
> ptr: *mut u8,
> length: usize,
> counter: u64,
> };
How is the pointer, length pair used in rust? Normally one would use a
slice so do we have to construct a slice every time we want to use the
data in this struct, or do we copy the data in this struct into to a an
idiomatic struct with a slice member? If we end up copying there doesn't
seem much point in changing all the types in the C struct as we can
define a rust struct using *c_char, c_long etc. to interface with the C
code and covert them to an appropriate rust type when we copy the data
to the idiomatic version that is then used by the rust of the rust code.
I can see the value of the typedefs for documenting C<->rust interop if
the same struct is used by both but if we end up copying data on the
rust side I'm not so sure.
Thanks
Phillip
next prev parent reply other threads:[~2025-07-31 14:20 UTC|newest]
Thread overview: 204+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-17 20:32 [PATCH 0/7] RFC: Accelerate xdiff and begin its rustification Ezekiel Newren via GitGitGadget
2025-07-17 20:32 ` [PATCH 1/7] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-07-17 21:30 ` brian m. carlson
2025-07-17 21:54 ` Junio C Hamano
2025-07-17 22:39 ` Taylor Blau
2025-07-18 23:15 ` Ezekiel Newren
2025-07-23 21:57 ` brian m. carlson
2025-07-23 22:26 ` Junio C Hamano
2025-07-28 19:11 ` Ezekiel Newren
2025-07-31 22:37 ` brian m. carlson
2025-07-22 22:02 ` Mike Hommey
2025-07-22 23:52 ` brian m. carlson
2025-07-17 22:38 ` Taylor Blau
2025-07-17 20:32 ` [PATCH 2/7] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-07-17 22:41 ` Taylor Blau
2025-07-17 20:32 ` [PATCH 3/7] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-07-17 20:32 ` [PATCH 4/7] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-07-17 22:46 ` Taylor Blau
2025-07-17 23:13 ` brian m. carlson
2025-07-17 23:37 ` Elijah Newren
2025-07-18 0:23 ` Taylor Blau
2025-07-18 0:21 ` Taylor Blau
2025-07-18 13:35 ` Phillip Wood
2025-07-28 19:34 ` Ezekiel Newren
2025-07-28 19:52 ` Phillip Wood
2025-07-28 20:14 ` Ezekiel Newren
2025-07-31 14:20 ` Phillip Wood [this message]
2025-07-31 20:58 ` Ezekiel Newren
2025-08-01 9:14 ` Phillip Wood
2025-07-28 20:53 ` Junio C Hamano
2025-07-28 20:00 ` Collin Funk
2025-07-20 1:39 ` Johannes Schindelin
2025-07-17 20:32 ` [PATCH 5/7] xdiff: separate parsing lines from hashing them Ezekiel Newren via GitGitGadget
2025-07-17 22:59 ` Taylor Blau
2025-07-18 13:34 ` Phillip Wood
2025-07-17 20:32 ` [PATCH 6/7] xdiff: conditionally use Rust's implementation of xxhash Ezekiel Newren via GitGitGadget
2025-07-17 23:29 ` Taylor Blau
2025-07-18 19:00 ` Junio C Hamano
2025-07-31 21:13 ` Ezekiel Newren
2025-08-02 7:53 ` Matthias Aßhauer
2025-07-19 21:53 ` Johannes Schindelin
2025-07-20 10:14 ` Phillip Wood
2025-09-23 9:57 ` gitoxide-compatible licensing of Git's Rust code, was " Johannes Schindelin
2025-09-23 17:48 ` Jeff King
2025-09-24 13:48 ` Phillip Wood
2025-09-25 2:25 ` Jeff King
2025-09-25 5:42 ` Patrick Steinhardt
2025-09-26 10:06 ` Phillip Wood
2025-10-03 3:18 ` Jeff King
2025-10-03 9:51 ` Phillip Wood
2025-10-07 9:11 ` Patrick Steinhardt
2025-11-17 13:37 ` Johannes Schindelin
2025-10-05 5:32 ` Yee Cheng Chin
2025-07-17 20:32 ` [PATCH 7/7] github_workflows: install rust Ezekiel Newren via GitGitGadget
2025-07-17 21:23 ` brian m. carlson
2025-07-18 23:01 ` Ezekiel Newren
2025-07-25 23:56 ` Ben Knoble
2025-07-19 21:54 ` Johannes Schindelin
2025-07-17 21:51 ` [PATCH 0/7] RFC: Accelerate xdiff and begin its rustification brian m. carlson
2025-07-17 22:25 ` Taylor Blau
2025-07-18 0:29 ` brian m. carlson
2025-07-22 12:21 ` Patrick Steinhardt
2025-07-22 15:56 ` Junio C Hamano
2025-07-22 16:03 ` Sam James
2025-07-22 21:37 ` Elijah Newren
2025-07-22 21:55 ` Sam James
2025-07-22 22:08 ` Collin Funk
2025-07-18 9:23 ` Christian Brabandt
2025-07-18 16:26 ` Junio C Hamano
2025-07-19 0:32 ` Elijah Newren
2025-07-18 13:34 ` Phillip Wood
2025-07-18 21:25 ` Eli Schwartz
2025-07-19 0:48 ` Haelwenn (lanodan) Monnier
2025-07-22 12:21 ` Patrick Steinhardt
2025-07-22 14:24 ` Patrick Steinhardt
2025-07-22 15:14 ` Eli Schwartz
2025-07-22 15:56 ` Sam James
2025-07-23 4:32 ` Patrick Steinhardt
2025-07-24 9:01 ` Pierre-Emmanuel Patry
2025-07-24 10:00 ` Patrick Steinhardt
2025-07-28 9:06 ` Pierre-Emmanuel Patry
2025-07-18 14:38 ` Junio C Hamano
2025-07-18 21:56 ` Ezekiel Newren
2025-07-21 10:14 ` Phillip Wood
2025-07-21 18:33 ` Junio C Hamano
2025-07-19 21:53 ` Johannes Schindelin
2025-07-20 8:45 ` Matthias Aßhauer
2025-08-15 1:22 ` [PATCH v2 00/17] " Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 01/17] doc: add a policy for using Rust brian m. carlson via GitGitGadget
2025-08-15 17:03 ` Matthias Aßhauer
2025-08-15 21:31 ` Junio C Hamano
2025-08-16 8:06 ` Matthias Aßhauer
2025-08-19 2:06 ` Ezekiel Newren
2025-08-15 1:22 ` [PATCH v2 02/17] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 03/17] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 04/17] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 05/17] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 06/17] xdiff: separate parsing lines from hashing them Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 07/17] xdiff: conditionally use Rust's implementation of xxhash Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 08/17] github workflows: install rust Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 09/17] Do support Windows again after requiring Rust Johannes Schindelin via GitGitGadget
2025-08-15 17:12 ` Matthias Aßhauer
2025-08-15 21:48 ` Junio C Hamano
2025-08-15 22:11 ` Johannes Schindelin
2025-08-15 23:37 ` Junio C Hamano
2025-08-15 23:37 ` Junio C Hamano
2025-08-16 8:53 ` Matthias Aßhauer
2025-08-17 15:57 ` Junio C Hamano
2025-08-19 2:22 ` Ezekiel Newren
2025-08-15 1:22 ` [PATCH v2 10/17] win+Meson: allow for xdiff to be compiled with MSVC Johannes Schindelin via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 11/17] win+Meson: do allow linking with the Rust-built xdiff Johannes Schindelin via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 12/17] github workflows: define rust versions and targets in the same place Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 13/17] github workflows: upload Cargo.lock Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 14/17] xdiff: implement a white space iterator in Rust Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 15/17] xdiff: create line_hash() and line_equal() Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 16/17] xdiff: optimize case where --ignore-cr-at-eol is the only whitespace flag Ezekiel Newren via GitGitGadget
2025-08-15 1:22 ` [PATCH v2 17/17] xdiff: use rust's version of whitespace processing Ezekiel Newren via GitGitGadget
2025-08-15 15:07 ` [-SPAM-] [PATCH v2 00/17] RFC: Accelerate xdiff and begin its rustification Ramsay Jones
2025-08-19 2:00 ` Elijah Newren
2025-08-24 16:52 ` Patrick Steinhardt
2025-08-18 22:31 ` Junio C Hamano
2025-08-18 23:52 ` Ben Knoble
2025-08-19 1:52 ` Elijah Newren
2025-08-19 9:47 ` Junio C Hamano
2025-08-23 3:55 ` [PATCH v3 00/15] RFC: Cleanup " Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 01/15] doc: add a policy for using Rust brian m. carlson via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 02/15] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-08-23 13:43 ` rsbecker
2025-08-23 14:26 ` Kristoffer Haugsbakk
2025-08-23 15:06 ` rsbecker
2025-08-23 18:30 ` Elijah Newren
2025-08-23 19:24 ` brian m. carlson
2025-08-23 20:04 ` rsbecker
2025-08-23 20:36 ` Sam James
2025-08-23 21:17 ` Haelwenn (lanodan) Monnier
2025-08-27 1:57 ` Taylor Blau
2025-08-27 14:39 ` rsbecker
2025-08-27 17:06 ` Junio C Hamano
2025-08-27 17:15 ` rsbecker
2025-08-27 20:12 ` Taylor Blau
2025-08-27 20:22 ` Junio C Hamano
2025-09-02 11:16 ` Patrick Steinhardt
2025-09-02 11:30 ` Sam James
2025-09-02 17:27 ` brian m. carlson
2025-09-02 18:47 ` Sam James
2025-09-03 18:22 ` Collin Funk
2025-09-03 5:40 ` Patrick Steinhardt
2025-09-03 16:22 ` Ramsay Jones
2025-09-03 22:10 ` Junio C Hamano
2025-09-03 22:48 ` Josh Steadmon
2025-09-04 11:10 ` Patrick Steinhardt
2025-09-04 15:45 ` Junio C Hamano
2025-09-05 8:23 ` Patrick Steinhardt
2025-09-04 0:57 ` brian m. carlson
2025-09-04 11:39 ` Patrick Steinhardt
2025-09-04 13:53 ` Sam James
2025-09-05 3:55 ` Elijah Newren
2025-09-04 23:17 ` Ezekiel Newren
2025-09-05 3:54 ` Elijah Newren
2025-09-05 6:50 ` Patrick Steinhardt
2025-09-07 4:10 ` Elijah Newren
2025-09-07 16:09 ` rsbecker
2025-09-08 10:12 ` Phillip Wood
2025-09-08 15:32 ` rsbecker
2025-09-08 15:10 ` Ezekiel Newren
2025-09-08 15:41 ` rsbecker
2025-09-08 15:31 ` Elijah Newren
2025-09-08 15:36 ` rsbecker
2025-09-08 16:13 ` Elijah Newren
2025-09-08 17:01 ` rsbecker
2025-09-08 6:40 ` Patrick Steinhardt
2025-09-05 10:31 ` Phillip Wood
2025-09-05 11:32 ` Sam James
2025-09-05 13:14 ` Phillip Wood
2025-09-05 13:23 ` Patrick Steinhardt
2025-09-05 15:37 ` Junio C Hamano
2025-09-08 6:40 ` Patrick Steinhardt
2025-08-23 14:29 ` Ezekiel Newren
2025-08-23 3:55 ` [PATCH v3 03/15] github workflows: install rust Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 04/15] win+Meson: do allow linking with the Rust-built xdiff Johannes Schindelin via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 05/15] github workflows: upload Cargo.lock Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 06/15] ivec: create a vector type that is interoperable between C and Rust Ezekiel Newren via GitGitGadget
2025-08-23 8:12 ` Kristoffer Haugsbakk
2025-08-23 9:29 ` Ezekiel Newren
2025-08-23 16:14 ` Junio C Hamano
2025-08-23 16:37 ` Ezekiel Newren
2025-08-23 18:05 ` Junio C Hamano
2025-08-23 20:29 ` Ezekiel Newren
2025-08-25 19:16 ` Elijah Newren
2025-08-26 5:40 ` Junio C Hamano
2025-08-24 13:31 ` Ben Knoble
2025-08-25 20:40 ` Ezekiel Newren
2025-08-26 13:30 ` D. Ben Knoble
2025-08-26 18:47 ` Ezekiel Newren
2025-08-26 22:01 ` brian m. carlson
2025-08-23 3:55 ` [PATCH v3 07/15] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 08/15] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 09/15] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 10/15] xdiff: use one definition for freeing xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 11/15] xdiff: replace chastore with an ivec in xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 12/15] xdiff: delete nrec field from xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 13/15] xdiff: delete recs " Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 14/15] xdiff: make xdfile_t more rust friendly Ezekiel Newren via GitGitGadget
2025-08-23 3:55 ` [PATCH v3 15/15] xdiff: implement xdl_trim_ends() in Rust Ezekiel Newren via GitGitGadget
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