The compile_data attribute can now be gathered from dependencies

proto/proto.bzl

@@ -234,6 +234,7 @@ def _rust_proto_compile(protos, descriptor_sets, imports, crate_name, ctx, is_gr
             edition = proto_toolchain.edition,
             rustc_env = {},
             is_test = False,
+            compile_data = depset([target.files for target in getattr(ctx.attr, "compile_data", [])]),
             wrapped_crate_type = None,
         ),
         output_hash = output_hash,

rust/private/providers.bzl

@@ -18,6 +18,7 @@ CrateInfo = provider(
     doc = "A provider containing general Crate information.",
     fields = {
         "aliases": "Dict[Label, String]: Renamed and aliased crates",
+        "compile_data": "depset[File]: Compile data required by this crate.",
         "deps": "depset[Provider]: This crate's (rust or cc) dependencies' providers.",
         "edition": "str: The edition of this crate.",
         "is_test": "bool: If the crate is being compiled in a test context",
@@ -39,7 +40,7 @@ DepInfo = provider(
     doc = "A provider containing information about a Crate's dependencies.",
     fields = {
         "dep_env": "File: File with environment variables direct dependencies build scripts rely upon.",
-        "direct_crates": "depset[CrateInfo]",
+        "direct_crates": "depset[AliasableDepInfo]",
         "transitive_build_infos": "depset[BuildInfo]",
         "transitive_crates": "depset[CrateInfo]",
         "transitive_libs": "List[File]: All transitive dependencies, not filtered by type.",

rust/private/rust.bzl

@@ -266,6 +266,7 @@ def _rust_library_common(ctx, crate_type):
             edition = get_edition(ctx.attr, toolchain),
             rustc_env = ctx.attr.rustc_env,
             is_test = False,
+            compile_data = depset(ctx.files.compile_data),
         ),
         output_hash = output_hash,
     )
@@ -301,6 +302,7 @@ def _rust_binary_impl(ctx):
             edition = get_edition(ctx.attr, toolchain),
             rustc_env = ctx.attr.rustc_env,
             is_test = False,
+            compile_data = depset(ctx.files.compile_data),
         ),
     )
 
@@ -418,6 +420,7 @@ def _rust_test_common(ctx, toolchain, output):
             edition = crate.edition,
             rustc_env = ctx.attr.rustc_env,
             is_test = True,
+            compile_data = depset(crate.compile_data),
             wrapped_crate_type = crate.type,
         )
     else:
@@ -434,6 +437,7 @@ def _rust_test_common(ctx, toolchain, output):
             edition = get_edition(ctx.attr, toolchain),
             rustc_env = ctx.attr.rustc_env,
             is_test = True,
+            compile_data = depset(ctx.files.compile_data),
         )
 
     providers = rustc_compile_action(

rust/private/rustc.bzl

@@ -266,7 +266,7 @@ def collect_inputs(
     Args:
         ctx (ctx): The rule's context object.
         file (struct): A struct containing files defined in label type attributes marked as `allow_single_file`.
-        files (list): A list of all inputs.
+        files (list): A list of all inputs (`ctx.files`).
         toolchain (rust_toolchain): The current `rust_toolchain`.
         cc_toolchain (CcToolchainInfo): The current `cc_toolchain`.
         crate_info (CrateInfo): The Crate information of the crate to process build scripts for.
@@ -280,9 +280,11 @@ def collect_inputs(
 
     linker_depset = cc_toolchain.all_files
 
+    # Collect compile data from the crate's dependencies
+    transitive_compile_data = depset(transitive = [info.compile_data for info in dep_info.transitive_crates.to_list()])
+
     compile_inputs = depset(
         getattr(files, "data", []) +
-        getattr(files, "compile_data", []) +
         [toolchain.rustc] +
         toolchain.crosstool_files +
         ([build_info.rustc_env, build_info.flags] if build_info else []) +
@@ -293,6 +295,8 @@ def collect_inputs(
             linker_depset,
             crate_info.srcs,
             dep_info.transitive_libs,
+            transitive_compile_data,
+            crate_info.compile_data,
         ],
     )
     build_env_files = getattr(files, "rustc_env_files", [])

test/compile_data/BUILD.bazel

@@ -0,0 +1,21 @@
+load("//rust:defs.bzl", "rust_library", "rust_test")
+
+# Note that this is the only target which assigns the `compile_data` attribute
+rust_library(
+    name = "compile_data",
+    srcs = ["compile_data.rs"],
+    compile_data = ["compile_data.txt"],
+    edition = "2018",
+)
+
+rust_test(
+    name = "compile_data_unit_test",
+    crate = ":compile_data",
+)
+
+rust_test(
+    name = "compile_data_integration_test",
+    srcs = ["compile_data_test.rs"],
+    edition = "2018",
+    deps = [":compile_data"],
+)

test/compile_data/compile_data.rs

@@ -0,0 +1,9 @@
+/// Data loaded from compile data
+pub const COMPILE_DATA: &'static str = include_str!("compile_data.txt");
+
+/// A test that is expected to be compiled from a target that does not
+/// directly populate the `compile_data` attribute
+#[test]
+fn test_compile_data_contents() {
+    assert_eq!(COMPILE_DATA, "compile data contents\n");
+}

test/compile_data/compile_data.txt

@@ -0,0 +1 @@
+compile data contents

test/compile_data/compile_data_test.rs

@@ -0,0 +1,9 @@
+use compile_data::COMPILE_DATA;
+
+#[test]
+fn test_compile_data_contents() {
+    // This would confirm that the constant that's compiled into the `compile_data`
+    // crate matches the data loaded at compile time here. Where `compile_data.txt`
+    // would have only been provided by the `compile_data` crate itself.
+    assert_eq!(COMPILE_DATA, include_str!("compile_data.txt"));
+}