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From: Taylor Blau <me@ttaylorr•com>
To: Ezekiel Newren via GitGitGadget <gitgitgadget@gmail•com>
Cc: git@vger•kernel.org, Elijah Newren <newren@gmail•com>,
	Ezekiel Newren <ezekielnewren@gmail•com>
Subject: Re: [PATCH 1/7] xdiff: introduce rust
Date: Thu, 17 Jul 2025 18:38:19 -0400	[thread overview]
Message-ID: <aHl7W5bDOGsORLLO@nand.local> (raw)
In-Reply-To: <2a1f4be13dfbdee21811b7a4907f99042c791c2d.1752784344.git.gitgitgadget@gmail.com>

On Thu, Jul 17, 2025 at 08:32:18PM +0000, Ezekiel Newren via GitGitGadget wrote:
> From: Ezekiel Newren <ezekielnewren@gmail•com>
>
> Upcoming patches will accelerate and simplify xdiff, while also
> porting parts of it to Rust. In preparation, add some stubs and setup
> the Rust build. For now, it is easier to let cargo build rust and
> have make or meson merely link against the static library that cargo
> builds. In line with ongoing libification efforts, use multiple
> crates to allow more modularity on the Rust side. xdiff is the crate
> that this series will focus on, but we also introduce the interop
> crate for future patch series.
>
> In order to facilitate interoperability between C and Rust, introduce
> C definitions for Rust primitive types in git-compat-util.h.

Exciting ;-).

> diff --git a/Makefile b/Makefile
> index 70d1543b6b86..db39e6e1c28e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -919,6 +919,11 @@ TEST_SHELL_PATH = $(SHELL_PATH)
>
>  LIB_FILE = libgit.a
>  XDIFF_LIB = xdiff/lib.a
> +ifeq ($(DEBUG), 1)
> +RUST_LIB = rust/target/debug/libxdiff.a
> +else
> +RUST_LIB = rust/target/release/libxdiff.a
> +endif

We do have a DEBUG variable in our Makefile introduced via dce7d29551
(msvc: support building Git using MS Visual C++, 2019-06-25), but I
don't think that it is very widely used. Perhaps that is because I don't
build Git with MSVC, but I suspect that this is generally true.

Much more common is the DEVELOPER=1 setting, which adds more compiler
warnings and similar. I am not sure whether or not it would be
appropriate to use DEVELOPER here to determine which libxdiff.a to use.

In any event, our convention would be to treat the defined-ness of DEBUG
the same way that this patch treats DEBUG=1, so I might suggest
replacing your "ifeq" with "ifdef DEBUG".

>  REFTABLE_LIB = reftable/libreftable.a
>
>  GENERATED_H += command-list.h
> @@ -1392,6 +1397,8 @@ UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/lib-reftable.o
>  GITLIBS = common-main.o $(LIB_FILE) $(XDIFF_LIB) $(REFTABLE_LIB) $(LIB_FILE)
>  EXTLIBS =
>
> +GITLIBS += $(RUST_LIB)
> +
>  GIT_USER_AGENT = git/$(GIT_VERSION)
>
>  ifeq ($(wildcard sha1collisiondetection/lib/sha1.h),sha1collisiondetection/lib/sha1.h)
> @@ -2925,6 +2932,14 @@ $(LIB_FILE): $(LIB_OBJS)
>  $(XDIFF_LIB): $(XDIFF_OBJS)
>  	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
>
> +.PHONY: $(RUST_LIB)
> +$(RUST_LIB):
> +ifeq ($(DEBUG), 1)
> +	cd rust && RUSTFLAGS="-Aunused_imports -Adead_code" cargo build --verbose

A few thoughts here:

 - Does "cargo" support a flag similar to our -C? If so, I wonder if it
   might be worth writing "cargo -C rust build ..." instead of "cd rust
   && ...".

 - This conditional on DEBUG passes the "--verbose" option in both
   cases. Should we only pass the "--verbose" option when we have "V=1"?

 - Regardless of whether or not we condition passing "--release" (or
   not) on "DEBUG", this line should also be "ifdef DEBUG" similar to
   above.

> +else
> +	cd rust && RUSTFLAGS="-Aunused_imports -Adead_code" cargo build --verbose --release
> +endif
> +
>  $(REFTABLE_LIB): $(REFTABLE_OBJS)
>  	$(QUIET_AR)$(RM) $@ && $(AR) $(ARFLAGS) $@ $^
>
> @@ -3756,7 +3771,10 @@ cocciclean:
>  	$(RM) -r .build/contrib/coccinelle
>  	$(RM) contrib/coccinelle/*.cocci.patch
>
> -clean: profile-clean coverage-clean cocciclean
> +rustclean:

I'm nitpicking, and we don't *really* have a convention here between
separating the clean target from "clean", as we have both
"profile-clean" and "cocciclean". I prefer the former, and think that it
would be nice to use that convention, but this is pretty much textbook
bike-shedding and not something that I really care about ;-).

> +	cd rust && cargo clean

Same question here about whether or not this could be written as "cargo
-C clean".

> diff --git a/git-compat-util.h b/git-compat-util.h
> index 4678e21c4cb8..82dc99764ac0 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -196,6 +196,23 @@ static inline int is_xplatform_dir_sep(int c)
>  #include "compat/msvc.h"
>  #endif
>
> +/* rust types */
> +typedef uint8_t   u8;
> +typedef uint16_t  u16;
> +typedef uint32_t  u32;
> +typedef uint64_t  u64;
> +
> +typedef int8_t    i8;
> +typedef int16_t   i16;
> +typedef int32_t   i32;
> +typedef int64_t   i64;
> +
> +typedef float     f32;
> +typedef double    f64;
> +
> +typedef size_t    usize;
> +typedef ptrdiff_t isize;
> +

Makes sense. Should we also have "bool" here (assuming that the series
declaring the "use bool" experiment a success lands)? I guess maybe not
either way, <stdbool.h> defines "bool" as the type name, identically to
Rust.

Thanks,
Taylor

  parent reply	other threads:[~2025-07-17 22:38 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 [this message]
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
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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