Minimum edits to not use the worker for the worker but use the worker for other things.

Author: nikhilm

proto/raze/remote/byteorder-1.3.4.BUILD

@@ -17,7 +17,7 @@ licenses([
 
 load(
     "@io_bazel_rules_rust//rust:rust.bzl",
-    "rust_library",
+    "rust_no_worker_library",
     "rust_binary",
     "rust_test",
 )
@@ -26,7 +26,7 @@ load(
 # Unsupported target "bench" with type "bench" omitted
 # Unsupported target "build-script-build" with type "custom-build" omitted
 
-rust_library(
+rust_no_worker_library(
     name = "byteorder",
     crate_root = "src/lib.rs",
     crate_type = "lib",

proto/raze/remote/bytes-0.4.12.BUILD

@@ -17,15 +17,15 @@ licenses([
 
 load(
     "@io_bazel_rules_rust//rust:rust.bzl",
-    "rust_library",
+    "rust_no_worker_library",
     "rust_binary",
     "rust_test",
 )
 
 
 # Unsupported target "bytes" with type "bench" omitted
 
-rust_library(
+rust_no_worker_library(
     name = "bytes",
     crate_root = "src/lib.rs",
     crate_type = "lib",

proto/raze/remote/iovec-0.1.4.BUILD

@@ -17,14 +17,14 @@ licenses([
 
 load(
     "@io_bazel_rules_rust//rust:rust.bzl",
-    "rust_library",
+    "rust_no_worker_library",
     "rust_binary",
     "rust_test",
 )
 
 
 
-rust_library(
+rust_no_worker_library(
     name = "iovec",
     crate_root = "src/lib.rs",
     crate_type = "lib",

proto/raze/remote/libc-0.2.69.BUILD

@@ -17,7 +17,7 @@ licenses([
 
 load(
     "@io_bazel_rules_rust//rust:rust.bzl",
-    "rust_library",
+    "rust_no_worker_library",
     "rust_binary",
     "rust_test",
 )
@@ -26,7 +26,7 @@ load(
 # Unsupported target "build-script-build" with type "custom-build" omitted
 # Unsupported target "const_fn" with type "test" omitted
 
-rust_library(
+rust_no_worker_library(
     name = "libc",
     crate_root = "src/lib.rs",
     crate_type = "lib",

proto/raze/remote/protobuf-2.8.2.BUILD

@@ -17,7 +17,7 @@ licenses([
 
 load(
     "@io_bazel_rules_rust//rust:rust.bzl",
-    "rust_library",
+    "rust_no_worker_library",
     "rust_binary",
     "rust_test",
 )
@@ -27,7 +27,7 @@ load(
 # Unsupported target "coded_input_stream" with type "bench" omitted
 # Unsupported target "coded_output_stream" with type "bench" omitted
 
-rust_library(
+rust_no_worker_library(
     name = "protobuf",
     crate_root = "src/lib.rs",
     crate_type = "lib",

rust/private/rust.bzl

@@ -364,17 +364,15 @@ _rust_common_attrs = {
         ],
     ),
     "_cc_toolchain": attr.label(default = "@bazel_tools//tools/cpp:current_cc_toolchain"),
+    "_use_worker": attr.bool(default = False),
     "_process_wrapper": attr.label(
         default = "@io_bazel_rules_rust//util/process_wrapper",
         executable = True,
         allow_single_file = True,
         cfg = "exec",
     ),
-    "_process_wrapper_worker": attr.label(
-        default = "@rustc_worker//file",
-        # Actually we may want the persistent worker to be built by the rust rules themselves, but right now we are just going to use a binary.
+    "process_wrapper_worker": attr.label(
         executable = True,
-        allow_single_file = True,
         cfg = "exec",
     ),
 }
@@ -403,7 +401,7 @@ _rust_test_attrs = {
     ),
 }
 
-rust_library = rule(
+rust_no_worker_library = rule(
     _rust_library_impl,
     attrs = dict(_rust_common_attrs.items() +
                  _rust_library_attrs.items()),
@@ -479,6 +477,14 @@ INFO: Elapsed time: 1.245s, Critical Path: 1.01s
 """,
 )
 
+def rust_library(**kwargs):
+    # Discard
+    _ = kwargs.pop("process_wrapper_worker", None)
+    rust_no_worker_library(
+        process_wrapper_worker = Label("//worker:rustc-worker"),
+        **kwargs,
+    )
+
 _rust_binary_attrs = {
     "linker_script": attr.label(
         doc = _tidy("""
@@ -493,7 +499,7 @@ _rust_binary_attrs = {
     "out_binary": attr.bool(),
 }
 
-rust_binary = rule(
+rust_no_worker_binary = rule(
     _rust_binary_impl,
     attrs = dict(_rust_common_attrs.items() + _rust_binary_attrs.items()),
     executable = True,
@@ -589,6 +595,14 @@ Hello world
 """,
 )
 
+def rust_binary(**kwargs):
+    # Discard
+    _ = kwargs.pop("process_wrapper_worker", None)
+    rust_no_worker_binary(
+        process_wrapper_worker = Label("//worker:rustc-worker"),
+        **kwargs,
+    )
+
 rust_test = rule(
     _rust_test_impl,
     attrs = dict(_rust_common_attrs.items() +

rust/private/rustc.bzl

@@ -313,10 +313,12 @@ def construct_arguments(
 
     env = _get_rustc_env(ctx, toolchain)
 
+    using_worker = ctx.executable.process_wrapper_worker != None
     # Wrapper args first
     args = ctx.actions.args()
-    args.set_param_file_format("multiline")
-    args.use_param_file("@%s", use_always=True)
+    if using_worker:
+        args.set_param_file_format("multiline")
+        args.use_param_file("@%s", use_always=True)
 
     if build_env_file != None:
         args.add("--env-file", build_env_file)
@@ -485,15 +487,28 @@ def rustc_compile_action(
     else:
         formatted_version = ""
 
+    worker_exe = ctx.executable.process_wrapper_worker
+
+    if worker_exe != None:
+        run_exe = worker_exe
+        execution_requirements = { "supports-workers": "1" }
+        run_args = [ctx.executable._process_wrapper.path, toolchain.rustc.path, ctx.var["COMPILATION_MODE"], args]
+        tools = [ctx.executable._process_wrapper]
+    else:
+        run_exe = ctx.executable._process_wrapper
+        run_args = [args]
+        execution_requirements = {}
+        tools = []
+
     ctx.actions.run(
-        executable = ctx.executable._process_wrapper_worker,
+        executable = run_exe,
         inputs = compile_inputs,
         outputs = [crate_info.output],
-        tools = [ctx.executable._process_wrapper],
+        tools = tools,
         env = env,
-        arguments = [ctx.executable._process_wrapper.path, toolchain.rustc.path, ctx.var["COMPILATION_MODE"], args],
+        arguments = run_args,
         mnemonic = "Rustc",
-        execution_requirements = { "supports-workers": "1" },
+        execution_requirements = execution_requirements,
         progress_message = "Compiling Rust {} {}{} ({} files)".format(
             crate_info.type,
             ctx.label.name,

rust/rust.bzl

@@ -19,6 +19,8 @@ load(
     _rust_library = "rust_library",
     _rust_test = "rust_test",
     _rust_test_binary = "rust_test_binary",
+    _rust_no_worker_library = "rust_no_worker_library",
+    _rust_no_worker_binary = "rust_no_worker_binary",
 )
 load(
     "@io_bazel_rules_rust//rust:private/rustdoc.bzl",
@@ -60,3 +62,6 @@ rust_clippy_aspect = _rust_clippy_aspect
 
 rust_clippy = _rust_clippy
 """ See @io_bazel_rules_rust//rust:private/clippy.bzl for a complete description. """
+
+rust_no_worker_library = _rust_no_worker_library
+rust_no_worker_binary = _rust_no_worker_binary

worker/BUILD

@@ -1,42 +1,47 @@
 # load("@rules_proto//proto:defs.bzl", "proto_library")
 # load("@io_bazel_rules_rust//proto:proto.bzl", "rust_proto_library")
 # load("@io_bazel_rules_rust//proto:toolchain.bzl", "PROTO_COMPILE_DEPS", "rust_proto_toolchain")
-load("@io_bazel_rules_rust//rust:rust.bzl", "rust_library", "rust_binary")
+load("//rust:rust.bzl", "rust_no_worker_library", "rust_no_worker_binary")
 
-rust_library(
+rust_no_worker_library(
     name = "rustc_worker",
+    edition = "2018",
     srcs = [
         "src/lib.rs",
         "src/worker_protocol.rs",
     ],
     deps = [
-        "@io_bazel_rules_rust//proto/raze:protobuf",
+        "//proto/raze:protobuf",
     ],
 )
 
-rust_binary(
+rust_no_worker_binary(
     name = "rustc-worker",
+    edition = "2018",
     srcs = ["src/main.rs"],
     deps = [
         ":rustc_worker",
-        "@io_bazel_rules_rust//proto/raze:protobuf",
+        "//proto/raze:protobuf",
     ],
+    visibility = ["//visibility:public"],
 )
 
-# rust_proto_toolchain(name = "default-proto-toolchain-impl")
-# 
-# toolchain(
-#     name = "default-proto-toolchain",
-#     toolchain = ":default-proto-toolchain-impl",
-#     toolchain_type = "@io_bazel_rules_rust//proto:toolchain",
-# )
-# 
-# proto_library(
-#     name = "worker_protocol_proto",
-#     srcs = ["src/worker_protocol.proto"],
-# )
-# 
-# rust_proto_library(
-#     name = "worker_protocol",
-#     deps = [":worker_protocol_proto"],
-# )
+# The rust_* rules are required to build the worker
+# They shouldn't _use_ the worker when building the worker OR any of its dependencies
+# Ideally we want some transitive switch applier (like a custom transition?) that will enforce this across the entire dependency graph.
+# What does that look like?
+# Can we use transitions? Is that supported in Bazel 0.27?
+# Alternatively can we use a config-setting?
+# In that case, how do we enforce the config setting when building the worker?
+# Alternatively, we would need to make raze emit customizable rule names, then have it run in the custom mode to generate the BUILD files for the protobuf bits.
+
+# On the C++ side, the protobuf repo does provide a "protobuf" and "protobuf-lite" target to link the worker against, that will allow us to use protobufs easily.
+
+# we would need to write code to repeatedly execute the child process and capture stdout.
+# similarly, we would need to write code to parse args (actually that exists). 
+# we would need some equivalent of canonicalize (realpath on unix, GetFinalPathNameByHandle on windows), 
+# response file handling and reading
+# hashing the inputs
+# mkdir_all
+
+# otherwise edit the raze files...