Enable Rust code in V8 for workerd

.bazelrc

@@ -97,6 +97,11 @@ build:no-perfetto --//src/workerd/util:use_perfetto=False
 build:no-perfetto --@v8//:v8_use_perfetto=False
 build:unix --config=perfetto
 
+# Build V8's Temporal implementation on the temporal_capi crate from crates_vendor.
+# NOTE: Temporal is still disabled at runtime for now
+build --@v8//:v8_enable_temporal_support=True
+build --@v8//:v8_temporal_capi=//deps/rust:temporal_capi
+
 # Increasing the optimization level of V8 significantly speeds up tests using V8 a lot, especially
 # python tests. This is useful for both CI and local development and enabled by default, but still
 # kept in a separate configuration to make it easy to disable.

build/deps/rust.MODULE.bazel

@@ -105,6 +105,26 @@ crate.annotation(
     crate = "rust_icu_sys",
     rustc_env = {"RUST_ICU_MAJOR_VERSION_NUMBER": "78"},
 )
+crate.annotation(
+    # V8 includes generated C++ bindings in the temporal_capi crate; create a cc_library to access
+    # these from Bazel.
+    #
+    # Not a triple-quoted string: Windows checkouts convert this file to CRLF line endings, which
+    # would end up in the string and change crate_universe's lockfile digest.
+    additive_build_file_content = "\n".join([
+        "",
+        'load("@rules_cc//cc:cc_library.bzl", "cc_library")',
+        "",
+        "cc_library(",
+        '    name = "cpp_bindings",',
+        '    hdrs = glob(["bindings/cpp/**/*.hpp"]),',
+        '    strip_include_prefix = "bindings/cpp",',
+        ")",
+        "",
+    ]),
+    crate = "temporal_capi",
+    extra_aliased_targets = {"temporal_capi_cpp_bindings": "cpp_bindings"},
+)
 crate.from_cargo(
     # TODO(cleanup): This name is a bit misleading now that we don't vendor. We can clean it up as a
     # followup.

build/deps/v8.MODULE.bazel

@@ -72,6 +72,7 @@ PATCHES = [
     "0047-Add-v8-Data-IsCompatibleWithIsolate.patch",
     "0048-Keep-llvm-libc-private-to-v8_libbase.patch",
     "0049-Keep-v8_libshared-private-to-v8.patch",
+    "0050-Build-Temporal-in-the-V8-Bazel-build.patch",
 ]
 
 http_archive(

deps/rust/BUILD.bazel

@@ -43,3 +43,14 @@ rust_static_library(
     stamp = -1,  # default to bazel --stamp flag
     tags = ["manual"],
 )
+
+# Main target for V8 temporal. Consists of our rust runtime + temoral_capi crate + its C++ bindings.
+cc_library(
+    name = "temporal_capi",
+    visibility = ["//visibility:public"],
+    deps = [
+        ":runtime",
+        "@crates_vendor//:temporal_capi",
+        "@crates_vendor//:temporal_capi_cpp_bindings",
+    ],
+)

deps/rust/Cargo.toml

@@ -89,6 +89,12 @@ rustls-webpki = { version = "0.103", default-features = false }
 # param_extractor depends on unbounded_depth feature
 serde_json = { version = "1", features = ["unbounded_depth"] }
 serde = { version = "1", features = ["derive"] }
+# V8's Temporal implementation (//deps/rust:temporal_capi). V8 compiles against temporal_capi's
+# generated C++ headers, so both crates should be pinned to the versions and features the V8
+# release expects: those in Chromium's third_party/rust/chromium_crates_io/Cargo.toml, at the
+# third_party/rust revision pinned in V8's DEPS.
+temporal_capi = { version = "=0.2.6", features = ["zoneinfo64"] }
+temporal_rs = { version = "=0.2.6", default-features = false, features = ["float64_representable_durations"] }
 thiserror = "2"
 tower-service = "0.3"
 # tokio is huge, let's enable only features when we actually need them.