ci: cross-compile Windows Bazel tests (#20585)

## Status

This is the Bazel PR-CI cross-compilation follow-up to #20485. It is
intentionally split from the Cargo/cargo-xwin release-build PoC so
#20485 can stay as the historical release-build exploration. The
unrelated async-utils test cleanup has been moved to #20686, so this PR
is focused on the Windows Bazel CI path.

The intended tradeoff is now explicit in `.github/workflows/bazel.yml`:
pull requests get the fast Windows cross-compiled Bazel test leg, while
post-merge pushes to `main` run both that fast cross leg and a fully
native Windows Bazel test leg. The native main-only job keeps full
V8/code-mode coverage and gets a 40-minute timeout because it is less
latency-sensitive than PR CI. All other Bazel jobs remain at 30 minutes.

## Why

Windows Bazel PR CI currently does the expensive part of the build on
Windows. A native Windows Bazel test job on `main` completed in about
28m12s, leaving very little headroom under the 30-minute job timeout and
making Windows the slowest PR signal.

#20485 showed that Windows cross-compilation can be materially faster
for Cargo release builds, but PR CI needs Bazel because Bazel owns our
test sharding, flaky-test retries, and integration-test layout. This PR
applies the same high-level shape we already use for macOS Bazel CI:
compile with remote Linux execution, then run platform-specific tests on
the platform runner.

The compromise is deliberately signal-aware: code-mode/V8 changes are
rare enough that PR CI can accept losing the direct V8/code-mode
smoke-test signal temporarily, while `main` still runs the native
Windows job post-merge to catch that class of regression. A follow-up PR
should investigate making the cross-built Windows gnullvm V8 archive
pass the direct V8/code-mode tests so this tradeoff can eventually go
away.

## What Changed

- Adds a `ci-windows-cross` Bazel config that targets
`x86_64-pc-windows-gnullvm`, uses Linux RBE for build actions, and keeps
`TestRunner` actions local on the Windows runner.
- Adds explicit Windows platform definitions for
`windows_x86_64_gnullvm`, `windows_x86_64_msvc`, and a bridge toolchain
that lets gnullvm test targets execute under the Windows MSVC host
platform.
- Updates the Windows Bazel PR test leg to opt into the cross-compile
path via `--windows-cross-compile` and `--remote-download-toplevel`.
- Adds a `test-windows-native-main` job that runs only for `push` events
on `refs/heads/main`, uses the native Windows Bazel path, includes
V8/code-mode smoke tests, and has `timeout-minutes: 40`.
- Keeps fork/community PRs without `BUILDBUDDY_API_KEY` on the previous
local Windows MSVC-host fallback, including
`--host_platform=//:local_windows_msvc` and `--jobs=8`.
- Preserves the existing integration-test shape on non-gnullvm
platforms, while generating Windows-cross wrapper targets only for
`windows_gnullvm`.
- Resolves `CARGO_BIN_EXE_*` values from runfiles at test runtime,
avoiding hard-coded Cargo paths and duplicate test runfiles.
- Extends the V8 Bazel patches enough for the
`x86_64-pc-windows-gnullvm` target and Linux remote execution path.
- Makes the Windows sandbox test cwd derive from `INSTA_WORKSPACE_ROOT`
at runtime when Bazel provides it, because cross-compiled binaries may
contain Linux compile-time paths.
- Keeps the direct V8/code-mode unit smoke tests out of the Windows
cross PR path for now while native Windows CI continues to cover them
post-merge.

## Command Shape

The fast Windows PR test leg invokes the normal Bazel CI wrapper like
this:

```shell
./.github/scripts/run-bazel-ci.sh \
  --print-failed-action-summary \
  --print-failed-test-logs \
  --windows-cross-compile \
  --remote-download-toplevel \
  -- \
  test \
  --test_tag_filters=-argument-comment-lint \
  --test_verbose_timeout_warnings \
  --build_metadata=COMMIT_SHA=${GITHUB_SHA} \
  -- \
  //... \
  -//third_party/v8:all \
  -//codex-rs/code-mode:code-mode-unit-tests \
  -//codex-rs/v8-poc:v8-poc-unit-tests
```

With the BuildBuddy secret available on Windows, the wrapper selects
`--config=ci-windows-cross` and appends the important Windows-cross
overrides after rc expansion:

```shell
--host_platform=//:rbe
--shell_executable=/bin/bash
--action_env=PATH=/usr/bin:/bin
--host_action_env=PATH=/usr/bin:/bin
--test_env=PATH=${CODEX_BAZEL_WINDOWS_PATH}
```

The native post-merge Windows job intentionally omits
`--windows-cross-compile` and does not exclude the V8/code-mode unit
targets:

```shell
./.github/scripts/run-bazel-ci.sh \
  --print-failed-action-summary \
  --print-failed-test-logs \
  -- \
  test \
  --test_tag_filters=-argument-comment-lint \
  --test_verbose_timeout_warnings \
  --build_metadata=COMMIT_SHA=${GITHUB_SHA} \
  --build_metadata=TAG_windows_native_main=true \
  -- \
  //... \
  -//third_party/v8:all
```

## Research Notes

The existing macOS Bazel CI config already uses the model we want here:
build actions run remotely with `--strategy=remote`, but `TestRunner`
actions execute on the macOS runner. This PR mirrors that pattern for
Windows with `--strategy=TestRunner=local`.

The important Bazel detail is that `rules_rs` is already targeting
`x86_64-pc-windows-gnullvm` for Windows Bazel PR tests. This PR changes
where the build actions execute; it does not switch the Bazel PR test
target to Cargo, `cargo-nextest`, or the MSVC release target.

Cargo release builds differ from this Bazel path for V8: the normal
Windows Cargo release target is MSVC, and `rusty_v8` publishes prebuilt
Windows MSVC `.lib.gz` archives. The Bazel PR path targets
`windows-gnullvm`; `rusty_v8` does not publish a prebuilt Windows
GNU/gnullvm archive, so this PR builds that archive in-tree. That
Linux-RBE-built gnullvm archive currently crashes in direct V8/code-mode
smoke tests, which is why the workflow keeps native Windows coverage on
`main`.

The less obvious Bazel detail is test wrapper selection. Bazel chooses
the Windows test wrapper (`tw.exe`) from the test action execution
platform, not merely from the Rust target triple. The outer
`workspace_root_test` therefore declares the default test toolchain and
uses the bridge toolchain above so the test action executes on Windows
while its inner Rust binary is built for gnullvm.

The V8 investigation exposed a Windows-client gotcha: even when an
action execution platform is Linux RBE, Bazel can still derive the
genrule shell path from the Windows client. That produced remote
commands trying to run `C:\Program Files\Git\usr\bin\bash.exe` on Linux
workers. The wrapper now passes `--shell_executable=/bin/bash` with
`--host_platform=//:rbe` for the Windows cross path.

The same Windows-client/Linux-RBE boundary also affected
`third_party/v8:binding_cc`: a multiline genrule command can carry CRLF
line endings into Linux remote bash, which failed as `$'\r'`. That
genrule now keeps the `sed` command on one physical shell line while
using an explicit Starlark join so the shell arguments stay readable.

## Verification

Local checks included:

```shell
bash -n .github/scripts/run-bazel-ci.sh
bash -n workspace_root_test_launcher.sh.tpl
ruby -e "require %q{yaml}; YAML.load_file(%q{.github/workflows/bazel.yml}); puts %q{ok}"
RUNNER_OS=Linux ./scripts/list-bazel-clippy-targets.sh
RUNNER_OS=Windows ./scripts/list-bazel-clippy-targets.sh
RUNNER_OS=Linux ./tools/argument-comment-lint/list-bazel-targets.sh
RUNNER_OS=Windows ./tools/argument-comment-lint/list-bazel-targets.sh
```

The Linux clippy and argument-comment target lists contain zero
`*-windows-cross-bin` labels, while the Windows lists still include 47
Windows-cross internal test binaries.

CI evidence:

- Baseline native Windows Bazel test on `main`: success in about 28m12s,
https://github.com/openai/codex/actions/runs/25206257208/job/73907325959
- Green Windows-cross Bazel run on the split PR before adding the
main-only native leg: Windows test 9m16s, Windows release verify 5m10s,
Windows clippy 4m43s,
https://github.com/openai/codex/actions/runs/25231890068
- The latest SHA adds the explicit PR-vs-main tradeoff in `bazel.yml`;
CI is rerunning on that focused diff.

## Follow-Up

A subsequent PR should investigate making a cross-built Windows binary
work with V8/code-mode enabled. Likely options are either making the
Linux-RBE-built `windows-gnullvm` V8 archive correct at runtime, or
evaluating whether a Bazel MSVC target/toolchain can reuse the same
prebuilt MSVC `rusty_v8` archive shape that Cargo release builds already
use.
This commit is contained in:
Michael Bolin
2026-05-01 15:55:28 -07:00
committed by GitHub
parent a5fbcf1ab4
commit 466798aa83
14 changed files with 485 additions and 84 deletions

119
defs.bzl
View File

@@ -1,8 +1,8 @@
load("@crates//:data.bzl", "DEP_DATA")
load("@crates//:defs.bzl", "all_crate_deps")
load("@rules_platform//platform_data:defs.bzl", "platform_data")
load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_library", "rust_proc_macro", "rust_test")
load("@rules_rust//cargo/private:cargo_build_script_wrapper.bzl", "cargo_build_script")
load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_library", "rust_proc_macro", "rust_test")
PLATFORMS = [
"linux_arm64_musl",
@@ -31,6 +31,16 @@ WINDOWS_RUSTC_LINK_FLAGS = select({
"//conditions:default": [],
})
WINDOWS_GNULLVM_INCOMPATIBLE = select({
"@rules_rs//rs/experimental/platforms/constraints:windows_gnullvm": ["@platforms//:incompatible"],
"//conditions:default": [],
})
WINDOWS_GNULLVM_ONLY = select({
"@rules_rs//rs/experimental/platforms/constraints:windows_gnullvm": [],
"//conditions:default": ["@platforms//:incompatible"],
})
# libwebrtc uses Objective-C categories from native archives. Any Bazel-linked
# macOS binary/test that can pull it in must keep category symbols alive.
MACOS_WEBRTC_RUSTC_LINK_FLAGS = select({
@@ -64,12 +74,16 @@ def _workspace_root_test_impl(ctx):
test_bin = ctx.executable.test_bin
workspace_root_marker = ctx.file.workspace_root_marker
launcher_template = ctx.file._windows_launcher_template if is_windows else ctx.file._bash_launcher_template
runfile_env_exports = _windows_runfile_env_exports(ctx) if is_windows else _bash_runfile_env_exports(ctx)
workspace_root_setup = _windows_workspace_root_setup(ctx) if is_windows else _bash_workspace_root_setup(ctx)
ctx.actions.expand_template(
template = launcher_template,
output = launcher,
is_executable = True,
substitutions = {
"__RUNFILE_ENV_EXPORTS__": runfile_env_exports,
"__TEST_BIN__": test_bin.short_path,
"__WORKSPACE_ROOT_SETUP__": workspace_root_setup,
"__WORKSPACE_ROOT_MARKER__": workspace_root_marker.short_path,
},
)
@@ -78,6 +92,22 @@ def _workspace_root_test_impl(ctx):
for data_dep in ctx.attr.data:
runfiles = runfiles.merge(ctx.runfiles(files = data_dep[DefaultInfo].files.to_list()))
runfiles = runfiles.merge(data_dep[DefaultInfo].default_runfiles)
for runfile_dep in ctx.attr.runfile_env:
executable = runfile_dep[DefaultInfo].files_to_run.executable
if executable == None:
fail("{} does not provide an executable for runfile_env".format(runfile_dep.label))
runfiles = runfiles.merge(ctx.runfiles(files = [executable]))
runfiles = runfiles.merge(runfile_dep[DefaultInfo].default_runfiles)
location_targets = (
ctx.attr.data +
[ctx.attr.test_bin, ctx.attr.workspace_root_marker] +
ctx.attr.runfile_env.keys()
)
env = {
key: ctx.expand_location(value, targets = location_targets)
for key, value in ctx.attr.env.items()
}
return [
DefaultInfo(
@@ -86,18 +116,55 @@ def _workspace_root_test_impl(ctx):
runfiles = runfiles,
),
RunEnvironmentInfo(
environment = ctx.attr.env,
environment = env,
),
]
def _bash_runfile_env_exports(ctx):
lines = []
for runfile_dep, env_var in ctx.attr.runfile_env.items():
executable = runfile_dep[DefaultInfo].files_to_run.executable
if executable == None:
fail("{} does not provide an executable for runfile_env".format(runfile_dep.label))
lines.append('RUNFILE_ENV_ARGS+=("{}=$(resolve_runfile "{}")")'.format(env_var, executable.short_path))
return "\n".join(lines)
def _windows_runfile_env_exports(ctx):
lines = []
for runfile_dep, env_var in ctx.attr.runfile_env.items():
executable = runfile_dep[DefaultInfo].files_to_run.executable
if executable == None:
fail("{} does not provide an executable for runfile_env".format(runfile_dep.label))
lines.append('call :resolve_runfile {} "{}"'.format(env_var, executable.short_path))
lines.append("if errorlevel 1 exit /b 1")
return "\n".join(lines)
def _bash_workspace_root_setup(ctx):
if not ctx.attr.chdir_workspace_root:
return ""
return 'export INSTA_WORKSPACE_ROOT="${workspace_root}"\ncd "${workspace_root}"'
def _windows_workspace_root_setup(ctx):
if not ctx.attr.chdir_workspace_root:
return ""
return """set "INSTA_WORKSPACE_ROOT=%workspace_root%"
cd /d "%workspace_root%" || exit /b 1"""
workspace_root_test = rule(
implementation = _workspace_root_test_impl,
test = True,
toolchains = ["@bazel_tools//tools/test:default_test_toolchain_type"],
attrs = {
"chdir_workspace_root": attr.bool(
default = True,
),
"data": attr.label_list(
allow_files = True,
),
"env": attr.string_dict(),
"runfile_env": attr.label_keyed_string_dict(
cfg = "target",
),
"test_bin": attr.label(
cfg = "target",
executable = True,
@@ -255,6 +322,7 @@ def codex_rust_crate(
unit_test_name = name + "-unit-tests"
unit_test_binary = name + "-unit-tests-bin"
unit_test_shard_count = _test_shard_count(test_shard_counts, unit_test_name)
# Shard at the workspace_root_test layer. rules_rust's sharding wrapper
# expects to run from its own runfiles cwd, while workspace_root_test
# deliberately changes cwd so Insta sees Cargo-like snapshot paths.
@@ -298,9 +366,11 @@ def codex_rust_crate(
sanitized_binaries = []
cargo_env = {}
cargo_env_runfiles = {}
for binary, main in binaries.items():
#binary = binary.replace("-", "_")
sanitized_binaries.append(binary)
cargo_env_runfiles[":" + binary] = "CARGO_BIN_EXE_" + binary
cargo_env["CARGO_BIN_EXE_" + binary] = "$(rlocationpath :%s)" % binary
rust_binary(
@@ -317,6 +387,7 @@ def codex_rust_crate(
for binary_label in extra_binaries:
sanitized_binaries.append(binary_label)
binary = Label(binary_label).name
cargo_env_runfiles[binary_label] = "CARGO_BIN_EXE_" + binary
cargo_env["CARGO_BIN_EXE_" + binary] = "$(rlocationpath %s)" % binary_label
integration_test_kwargs = {}
@@ -331,6 +402,7 @@ def codex_rust_crate(
test_name = name + "-" + test_file_stem.replace("/", "-")
if not test_name.endswith("-test"):
test_name += "-test"
windows_cross_test_binary = test_name + "-windows-cross-bin"
test_kwargs = {}
test_kwargs.update(integration_test_kwargs)
@@ -340,6 +412,9 @@ def codex_rust_crate(
test_kwargs["shard_count"] = test_shard_count
test_kwargs["flaky"] = True
# Keep the existing integration test shape on non-gnullvm platforms.
# Windows cross tests need workspace_root_test so runfile env vars
# resolve to Windows-native absolute paths before the test starts.
rust_test(
name = test_name,
crate_name = test_crate_name,
@@ -356,14 +431,48 @@ def codex_rust_crate(
"--remap-path-prefix=codex-rs=",
],
rustc_env = rustc_env,
# Important: do not merge `test_env` here. Its unit-test-only
# `INSTA_WORKSPACE_ROOT="codex-rs"` is tuned for unit tests that
# execute from the repo root and can misplace integration snapshots.
env = cargo_env,
target_compatible_with = WINDOWS_GNULLVM_INCOMPATIBLE,
tags = test_tags,
**test_kwargs
)
windows_cross_test_kwargs = {}
windows_cross_test_kwargs.update(integration_test_kwargs)
if test_shard_count:
windows_cross_test_kwargs["shard_count"] = test_shard_count
windows_cross_test_kwargs["flaky"] = True
rust_test(
name = windows_cross_test_binary,
crate_name = test_crate_name,
crate_root = test,
srcs = [test],
data = native.glob(["tests/**"], allow_empty = True) + sanitized_binaries + test_data_extra,
compile_data = native.glob(["tests/**"], allow_empty = True) + integration_compile_data_extra,
deps = all_crate_deps(normal = True, normal_dev = True) + maybe_deps + deps_extra,
rustc_flags = rustc_flags_extra + WINDOWS_RUSTC_LINK_FLAGS + [
"--remap-path-prefix=../codex-rs=",
"--remap-path-prefix=codex-rs=",
],
rustc_env = rustc_env,
env = cargo_env,
target_compatible_with = WINDOWS_GNULLVM_ONLY,
tags = test_tags + ["manual"],
)
workspace_root_test(
name = test_name + "-windows-cross",
chdir_workspace_root = False,
env = cargo_env,
runfile_env = cargo_env_runfiles,
test_bin = ":" + windows_cross_test_binary,
workspace_root_marker = "//codex-rs/utils/cargo-bin:repo_root.marker",
target_compatible_with = WINDOWS_GNULLVM_ONLY,
tags = test_tags,
**windows_cross_test_kwargs
)
def _test_shard_count(test_shard_counts, test_name):
shard_count = test_shard_counts.get(test_name)
if shard_count == None: