On Sat, 19 Jul 2025, Johannes Schindelin wrote:
Hi Ezekiel,
pleasure to make your acquaintance!
On Thu, 17 Jul 2025, Ezekiel Newren via GitGitGadget wrote:
1. Windows fails to build. I don’t know which rust toolchain is even
correct for this or if multiple are needed. Example failed build:
https://github.com/git/git/actions/runs/16353209191
There are a couple of problems, not just one. Here are the patches that I
would like to ask you to take custody of (for your convenience, I have
pushed them to https://github.com/dscho/git as the `xdiff_rust_speedup`
branch). Please find them below. They _just_ fix the build, but the tests
with win+Meson still fail (and as "win+Meson test" jobs keep the logs of
the failed tests a well-guarded secret, due to time constraints I have to
stop looking into this for now).
Thank you for working on this,
Johannes
-- snipsnap --
From 72c50ee3f9df5ccfe48bf6f44b2c6bba05a680bf Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@xxxxxx>
Date: Sat, 19 Jul 2025 21:24:07 +0200
Subject: [PATCH 1/3] Do support Windows again after requiring Rust
By default, Rust wants to build MS Visual C-compatible libraries on
Windows, because that is _the_ native C compiler.
Git is historically lacking in its MSVC support, and the official Git
for Windows versions are built using GCC instead. As a consequence, a
(subset of a) GCC toolchain is installed as part of the `windows-build`
job of every CI build.
Naturally, this requires adjustments in how Rust is called, most
importantly it requires installing support for a GCC-compatible build
target.
Let's make the necessary adjustment both in the CI-specific code that
installs Rust as well as in the Windows-specific configuration in
`config.mak.uname`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
ci/install-rust.sh | 3 +++
config.mak.uname | 9 +++++++++
2 files changed, 12 insertions(+)
diff --git a/ci/install-rust.sh b/ci/install-rust.sh
index 141ceddb17cfe..c22baa629ceb7 100644
--- a/ci/install-rust.sh
+++ b/ci/install-rust.sh
@@ -28,6 +28,9 @@ if [ "$BITNESS" = "32" ]; then
$CARGO_HOME/bin/rustup default --force-non-host $RUST_VERSION || exit $?
else
$CARGO_HOME/bin/rustup default $RUST_VERSION || exit $?
+ if [ "$CI_OS_NAME" = "windows" ]; then
+ $CARGO_HOME/bin/rustup target add x86_64-pc-windows-gnu || exit $?
+ fi
fi
. $CARGO_HOME/env
diff --git a/config.mak.uname b/config.mak.uname
index 3e26bb074a4b5..fbe7cebf40edd 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -727,19 +727,28 @@ ifeq ($(uname_S),MINGW)
prefix = /mingw32
HOST_CPU = i686
BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup
+ CARGO_BUILD_TARGET = i686-pc-windows-gnu
While i686-pc-windows-gnu is fine for CI, it would mean we'd have to bump
our supported Windows version up to Windows 10. If we want to keep
supporting Windows 8.1, we'll need i686-win7-windows-gnu, at least on rust
1.78 and newer.[1][2] We'd probably build Windows versions on rust 1.88
currently.[3]
[1] https://blog.rust-lang.org/2024/02/26/Windows-7/
[2] https://doc.rust-lang.org/rustc/platform-support/win7-windows-gnu.html
[3] https://packages.msys2.org/base/mingw-w64-rust
endif
ifeq (MINGW64,$(MSYSTEM))
prefix = /mingw64
HOST_CPU = x86_64
BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
+ CARGO_BUILD_TARGET = x86_64-pc-windows-gnu
For x86_64 we'llprobably also want x86_64-win7-windows-gnu if we want to
keep Windows 8.1 support.
else ifeq (CLANGARM64,$(MSYSTEM))
prefix = /clangarm64
HOST_CPU = aarch64
BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
+ CARGO_BUILD_TARGET = aarch64-pc-windows-gnu
Are we sure this target currently exists? It's at least undocumented.[4] I
think we might want aarch64-pc-windows-gnullvm for CLANGARM64, either
way.[5]
[4] https://doc.rust-lang.org/rustc/platform-support/windows-gnu.html
[5] https://doc.rust-lang.org/rustc/platform-support/windows-gnullvm.html
Best regards
Matthias
else
COMPAT_CFLAGS += -D_USE_32BIT_TIME_T
BASIC_LDFLAGS += -Wl,--large-address-aware
endif
+
+ export CARGO_BUILD_TARGET
+ RUST_TARGET_DIR = rust/target/$(CARGO_BUILD_TARGET)/$(RUST_BUILD_MODE)
+ # Unfortunately now needed because of Rust
+ EXTLIBS += -luserenv
+
CC = gcc
COMPAT_CFLAGS += -D__USE_MINGW_ANSI_STDIO=0 -DDETECT_MSYS_TTY \
-fstack-protector-strong
--
2.50.1.windows.1
From ef6e4394ae26d8f28cb0d9e456810ce0818e623b Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@xxxxxx>
Date: Sat, 19 Jul 2025 23:08:11 +0200
Subject: [PATCH 2/3] win+Meson: allow for xdiff to be compiled with MSVC
The `build_rust.sh` script is quite opinionated about the naming scheme
of the C compiler: It assumes that the xdiff library file will be named
`libxdiff.a`.
However, MS Visual C generates `xdiff.lib` files instead; This naming
scheme has been in use in a very, very long time.
Let's allow for that.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
build_rust.sh | 7 ++++++-
meson.build | 12 +++++++++---
2 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/build_rust.sh b/build_rust.sh
index 4c12135cd2050..694d48d857a58 100755
--- a/build_rust.sh
+++ b/build_rust.sh
@@ -44,7 +44,12 @@ fi
cd $dir_rust && cargo clean && pwd && cargo build -p $crate $rust_args; cd ..
-libfile="lib${crate}.a"
+if grep x86_64-pc-windows-msvc rust/target/.rustc_info.json
+then
+ libfile="${crate}.lib"
+else
+ libfile="lib${crate}.a"
+fi
dst=$dir_build/$libfile
if [ "$dir_git_root" != "$dir_build" ]; then
diff --git a/meson.build b/meson.build
index 047d7e5b66306..5e89a5dd0e00f 100644
--- a/meson.build
+++ b/meson.build
@@ -277,8 +277,16 @@ else
rustflags = '-Aunused_imports -Adead_code -C debuginfo=2 -C opt-level=1 -C force-frame-pointers=yes'
endif
+compiler = meson.get_compiler('c')
+
+if compiler.get_id() == 'msvc'
+ xdiff_lib_filename = 'xdiff.lib'
+else
+ xdiff_lib_filename = 'libxdiff.a'
+endif
+
rust_build_xdiff = custom_target('rust_build_xdiff',
- output: 'libxdiff.a',
+ output: xdiff_lib_filename,
build_by_default: true,
build_always_stale: true,
command: [
@@ -288,8 +296,6 @@ rust_build_xdiff = custom_target('rust_build_xdiff',
install: false,
)
-compiler = meson.get_compiler('c')
-
libgit_sources = [
'abspath.c',
'add-interactive.c',
--
2.50.1.windows.1
From 9c3b017cfa069211027fbb1f6d3b97c8e7edda81 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@xxxxxx>
Date: Sat, 19 Jul 2025 23:22:57 +0200
Subject: [PATCH 3/3] win+Meson: do allow linking with the Rust-built xdiff
When linking against the Rust-built `xdiff`, there is now a new required
dependency: Without _also_ linking to the system library `userenv`, the
compile would fail with this error message:
xdiff.lib(std-c85e9beb7923f636.std.df32d1bc89881d89-cgu.0.rcgu.o) :
error LNK2019: unresolved external symbol __imp_GetUserProfileDirectoryW
referenced in function _ZN3std3env8home_dir17hfd1c3b6676cd78f6E
Therefore, just like we do in case of Makefile-based builds on Windows,
we now also link to that library when building with Meson.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
meson.build | 1 +
1 file changed, 1 insertion(+)
diff --git a/meson.build b/meson.build
index 5e89a5dd0e00f..af015f04763fd 100644
--- a/meson.build
+++ b/meson.build
@@ -1260,6 +1260,7 @@ elif host_machine.system() == 'windows'
]
libgit_dependencies += compiler.find_library('ntdll')
+ libgit_dependencies += compiler.find_library('userenv')
libgit_include_directories += 'compat/win32'
if compiler.get_id() == 'msvc'
libgit_include_directories += 'compat/vcbuild/include'
--
2.50.1.windows.1
