On Thu, Jul 17, 2025 at 08:32:18PM +0000, Ezekiel Newren via GitGitGadget wrote: > From: Ezekiel Newren <ezekielnewren@xxxxxxxxx> > > 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
