Do not pass native deps to rlib compilations

When creating an rlib artifact, rustc will open every
native static library and "copy" its contents into the rlib. This
results in a quadratic disk usage growth and that's not necessary for
rules_rust because we track native dependencies are we can safely pass
them to the final linking actions.

This fixes the build failure when a native dep is actually a linker
script. Rustc will try to open the linker script as if it was a static
archive, and then fail the build.

Creating shared library artifacts (dylib, cdylib) and binaries is not
affected, for those rustc uses the linker, and linker will consume the
linker script just fine. Rustc won't try to open/interpret the linker
script itself.

This also unblocks bazelbuild#562.

bindgen/bindgen.bzl

@@ -14,7 +14,6 @@
 
 # buildifier: disable=module-docstring
 load("//rust:rust.bzl", "rust_library")
-load("//rust/private:utils.bzl", "find_toolchain", "get_libs_for_static_executable")
 
 # buildifier: disable=bzl-visibility
 load("//rust/private:utils.bzl", "find_toolchain", "get_libs_for_static_executable")

cargo/cargo_build_script.bzl

@@ -2,9 +2,6 @@
 load("@bazel_tools//tools/build_defs/cc:action_names.bzl", "C_COMPILE_ACTION_NAME")
 load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
 load("//rust:rust.bzl", "rust_binary")
-load("//rust/private:rust.bzl", "name_to_crate_name")
-load("//rust/private:rustc.bzl", "BuildInfo", "DepInfo", "get_cc_toolchain", "get_compilation_mode_opts", "get_linker_and_args")
-load("//rust/private:utils.bzl", "expand_locations", "find_toolchain")
 
 # buildifier: disable=bzl-visibility
 load("//rust/private:rust.bzl", "name_to_crate_name")

proto/proto.bzl

@@ -217,6 +217,7 @@ def _rust_proto_compile(protos, descriptor_sets, imports, crate_name, ctx, is_gr
     return rustc_compile_action(
         ctx = ctx,
         toolchain = find_toolchain(ctx),
+        crate_type = "rlib",
         crate_info = rust_common.crate_info(
             name = crate_name,
             type = "rlib",

rust/BUILD

@@ -15,6 +15,7 @@ toolchain_type(
 
 bzl_library(
     name = "rules",
+    srcs = glob(["**/*.bzl"]),
     deps = [
         "//rust/platform:rules",
         "//rust/private:rules",

rust/private/BUILD

@@ -9,4 +9,4 @@ bzl_library(
     deps = [
         "//rust/platform:rules",
     ],
-)
+)

rust/private/clippy.bzl

@@ -49,6 +49,7 @@ def _clippy_aspect_impl(target, ctx):
 
     toolchain = find_toolchain(ctx)
     crate_info = target[rust_common.crate_info]
+    crate_type = crate_info.type
 
     if crate_info.is_test:
         root = crate_info.root
@@ -89,6 +90,7 @@ def _clippy_aspect_impl(target, ctx):
         toolchain.clippy_driver.path,
         cc_toolchain,
         feature_configuration,
+        crate_type,
         crate_info,
         dep_info,
         output_hash = determine_output_hash(root),

rust/private/rust.bzl

@@ -155,9 +155,10 @@ def _rust_library_impl(ctx):
     output_hash = determine_output_hash(crate_root)
 
     crate_name = name_to_crate_name(ctx.label.name)
+    crate_type = getattr(ctx.attr, "crate_type")
     rust_lib_name = _determine_lib_name(
         crate_name,
-        ctx.attr.crate_type,
+        crate_type,
         toolchain,
         output_hash,
     )
@@ -166,9 +167,10 @@ def _rust_library_impl(ctx):
     return rustc_compile_action(
         ctx = ctx,
         toolchain = toolchain,
+        crate_type = crate_type,
         crate_info = rust_common.crate_info(
             name = crate_name,
-            type = ctx.attr.crate_type,
+            type = crate_type,
             root = crate_root,
             srcs = ctx.files.srcs,
             deps = ctx.attr.deps,
@@ -201,6 +203,7 @@ def _rust_binary_impl(ctx):
     return rustc_compile_action(
         ctx = ctx,
         toolchain = toolchain,
+        crate_type = crate_type,
         crate_info = rust_common.crate_info(
             name = crate_name,
             type = crate_type,
@@ -230,14 +233,15 @@ def _rust_test_common(ctx, toolchain, output):
     _assert_no_deprecated_attributes(ctx)
 
     crate_name = name_to_crate_name(ctx.label.name)
-
+    crate_type = "lib"
     if ctx.attr.crate:
         # Target is building the crate in `test` config
         # Build the test binary using the dependency's srcs.
         crate = ctx.attr.crate[rust_common.crate_info]
+        crate_type = crate.type
         target = rust_common.crate_info(
             name = crate_name,
-            type = crate.type,
+            type = crate_type,
             root = crate.root,
             srcs = crate.srcs + ctx.files.srcs,
             deps = crate.deps + ctx.attr.deps,
@@ -252,7 +256,7 @@ def _rust_test_common(ctx, toolchain, output):
         # Target is a standalone crate. Build the test binary as its own crate.
         target = rust_common.crate_info(
             name = crate_name,
-            type = "lib",
+            type = crate_type,
             root = crate_root_src(ctx.attr, ctx.files.srcs, "lib"),
             srcs = ctx.files.srcs,
             deps = ctx.attr.deps,
@@ -267,6 +271,7 @@ def _rust_test_common(ctx, toolchain, output):
     return rustc_compile_action(
         ctx = ctx,
         toolchain = toolchain,
+        crate_type = crate_type,
         crate_info = target,
         rust_flags = ["--test"],
     )

rust/private/rustc.bzl

@@ -364,6 +364,7 @@ def construct_arguments(
         tool_path,
         cc_toolchain,
         feature_configuration,
+        crate_type,
         crate_info,
         dep_info,
         output_hash,
@@ -383,6 +384,7 @@ def construct_arguments(
         tool_path (str): Path to rustc
         cc_toolchain (CcToolchain): The CcToolchain for the current target.
         feature_configuration (FeatureConfiguration): Class used to construct command lines from CROSSTOOL features.
+        crate_type (str): Crate type of the current target.
         crate_info (CrateInfo): The CrateInfo provider of the target crate
         dep_info (DepInfo): The DepInfo provider of the target crate
         output_hash (str): The hashed path of the crate root
@@ -508,7 +510,7 @@ def construct_arguments(
             args.add("--codegen=linker=" + ld)
             args.add_joined("--codegen", link_args, join_with = " ", format_joined = "link-args=%s")
 
-        add_native_link_flags(args, dep_info)
+        add_native_link_flags(args, dep_info, crate_type)
 
     # These always need to be added, even if not linking this crate.
     add_crate_link_flags(args, dep_info)
@@ -541,6 +543,7 @@ def construct_arguments(
 def rustc_compile_action(
         ctx,
         toolchain,
+        crate_type,
         crate_info,
         output_hash = None,
         rust_flags = []):
@@ -549,6 +552,7 @@ def rustc_compile_action(
     Args:
         ctx (ctx): The rule's context object
         toolchain (rust_toolchain): The current `rust_toolchain`
+        crate_type (str): Crate type of the current target
         crate_info (CrateInfo): The CrateInfo provider for the current target.
         output_hash (str, optional): The hashed path of the crate root. Defaults to None.
         rust_flags (list, optional): Additional flags to pass to rustc. Defaults to [].
@@ -586,6 +590,7 @@ def rustc_compile_action(
         toolchain.rustc.path,
         cc_toolchain,
         feature_configuration,
+        crate_type,
         crate_info,
         dep_info,
         output_hash,
@@ -807,13 +812,18 @@ def _get_crate_dirname(crate):
     """
     return crate.output.dirname
 
-def add_native_link_flags(args, dep_info):
+def add_native_link_flags(args, dep_info, crate_type):
     """Adds linker flags for all dependencies of the current target.
 
     Args:
         args (Args): The Args struct for a ctx.action
-        dep_info (DepInfo): Dependeincy Info provider
+        dep_info (DepInfo): Dependency Info provider
+        crate_type: Crate type of the current target
+
     """
+    if crate_type in ["lib", "rlib"]:
+        return
+
     native_libs = depset(transitive = [dep_info.transitive_dylibs, dep_info.transitive_staticlibs])
     args.add_all(native_libs, map_each = _get_dirname, uniquify = True, format_each = "-Lnative=%s")
     args.add_all(dep_info.transitive_dylibs, map_each = get_lib_name, format_each = "-ldylib=%s")

rust/private/rustdoc.bzl

@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("//rust:rust_common.bzl", "CrateInfo")
-
 # buildifier: disable=module-docstring
 load("//rust/private:common.bzl", "rust_common")
 load("//rust/private:rustc.bzl", "DepInfo", "add_crate_link_flags", "add_edition_flags")

rust/private/rustdoc_test.bzl

@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load("//rust:rust_common.bzl", "CrateInfo")
-
 # buildifier: disable=module-docstring
 load("//rust/private:common.bzl", "rust_common")
 load("//rust/private:rustc.bzl", "DepInfo")

rust/rust.bzl

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 # buildifier: disable=module-docstring
+
 load(
     "//rust/private:clippy.bzl",
     _rust_clippy = "rust_clippy",

test/unit/BUILD

@@ -0,0 +1 @@
+# BUILD file intentionally left empty

test/unit/native_deps/BUILD

@@ -0,0 +1,4 @@
+load(":native_deps_test.bzl", "native_deps_test_suite")
+
+############################ UNIT TESTS #############################
+native_deps_test_suite(name = "native_deps_test_suite")

test/unit/native_deps/bin_using_native_dep.rs

@@ -0,0 +1,6 @@
+extern "C" {
+    fn native_dep() -> isize;
+}
+fn main() {
+    println!("{}", unsafe { native_dep() })
+}

test/unit/native_deps/lib_using_native_dep.rs

@@ -0,0 +1,6 @@
+extern "C" {
+    fn native_dep() -> isize;
+}
+pub fn use_native_dep() {
+    println!("{}", unsafe { native_dep() })
+}

test/unit/native_deps/native_dep.cc

@@ -0,0 +1 @@
+extern "C" int native_dep() { return 42; }