Allow extra packages to be added to oak crate indexes.

Other projects using Oak may have additional dependencies. Per
bazelbuild/rules_rust#1609 (comment),
it's recommended that a target only pull dependencies from a single
`crates_repository` target, so those projects shouldn't define their own
crates repository. Instead, they should augment the Oak-defined ones.

I preferred this approach over exporting Oak's deps and annotations
because that's harder to use: (a) it requires defining crates
repositories with the Oak-expected names (or using repo mapping), and
(b) it doesn't work cleanly with Oak's jemalloc repository.

Bug: 355397572
Change-Id: I672d5bcb4dc629904e9944ff7c07b2ae674edbd9

bazel/crates/oak_crates_index.bzl

@@ -27,7 +27,7 @@ load("@rules_rust//crate_universe:defs.bzl", "crate", "crates_repository")
 load("//bazel/crates:jemalloc.bzl", "jemalloc_repository")
 load("//bazel/rust:defs.bzl", "RUST_NIGHTLY_VERSION")
 
-def oak_crates_index(cargo_lockfile, lockfile):
+def oak_crates_index(cargo_lockfile, lockfile, extra_annotations = {}, extra_packages = {}):
     jemalloc_repository()
 
     # Default crate repository - some crates may require std.
@@ -58,7 +58,7 @@ def oak_crates_index(cargo_lockfile, lockfile):
             "tokio": [crate.annotation(
                 rustc_flags = ["--cfg=tokio_unstable"],
             )],
-        },
+        } | extra_annotations,
         cargo_lockfile = cargo_lockfile,  # In Cargo-free mode this is used as output, not input.
         lockfile = lockfile,  # Shares most contents with cargo_lockfile.
         packages = {
@@ -493,7 +493,7 @@ def oak_crates_index(cargo_lockfile, lockfile):
             "rand_chacha": crate.spec(
                 version = "*",
             ),
-        },
+        } | extra_packages,
         rust_version = RUST_NIGHTLY_VERSION,
         # We request bare metal support. Because of feature unification, some creates
         # in this repository may end up requiring std, thus not being compatible

bazel/crates/oak_no_std_crates_index.bzl

@@ -26,10 +26,11 @@
 load("@rules_rust//crate_universe:defs.bzl", "crate", "crates_repository")
 load("//bazel/rust:defs.bzl", "RUST_NIGHTLY_VERSION")
 
-def oak_no_std_crates_index(cargo_lockfile, lockfile):
+def oak_no_std_crates_index(cargo_lockfile, lockfile, extra_annotations = {}, extra_packages = {}):
     # All creates in this repository must support no_std.
     crates_repository(
         name = "oak_no_std_crates_index",
+        annotations = extra_annotations,
         cargo_lockfile = cargo_lockfile,  # In Cargo-free mode this is used as output, not input.
         lockfile = lockfile,  # Shares most contents with cargo_lockfile.
         packages = {
@@ -193,7 +194,7 @@ def oak_no_std_crates_index(cargo_lockfile, lockfile):
                 # same version as cargo, newer versions had compatibility issues
                 version = "0.31.2",
             ),
-        },
+        } | extra_packages,
         rust_version = RUST_NIGHTLY_VERSION,
         supported_platform_triples = [
             # Linux for dependencies of build scripts (they run on host):

bazel/crates/repositories.bzl

@@ -36,9 +36,23 @@ load("//bazel/crates:oak_no_std_crates_index.bzl", "oak_no_std_crates_index")
 
 def create_oak_crate_repositories(
         cargo_lockfile = "//:Cargo.bazel.lock",
+        extra_annotations = {},
+        extra_no_std_annotations = {},
+        extra_no_std_packages = {},
+        extra_packages = {},
         lockfile = "//:cargo-bazel-lock.json",
         no_std_cargo_lockfile = "//:Cargo_no_std.bazel.lock",
         no_std_lockfile = "//:cargo-no-std-bazel-lock.json"):
     crate_universe_dependencies(bootstrap = True)
-    oak_crates_index(cargo_lockfile, lockfile)
-    oak_no_std_crates_index(no_std_cargo_lockfile, no_std_lockfile)
+    oak_crates_index(
+        cargo_lockfile,
+        lockfile,
+        extra_annotations = extra_annotations,
+        extra_packages = extra_packages,
+    )
+    oak_no_std_crates_index(
+        no_std_cargo_lockfile,
+        no_std_lockfile,
+        extra_annotations = extra_no_std_annotations,
+        extra_packages = extra_no_std_packages,
+    )