Add `rust_expand` and `rust_expand_aspect` for generating macro expanded source files. #1643

freeformstu · 2022-11-09T03:28:53Z

Proposal for #1642

Summary

Rustc can be used to expand all macros so that you can inspect the generated source files easier.

This feature is enabled via -Zunpretty=expanded. The -Z flag is only available in the nightly
version of rustc.

Expanding

Build and test your targets normally.

bazel build //:ok_binary   
INFO: Analyzed target //:ok_binary (0 packages loaded, 0 targets configured).
INFO: Found 1 target...
Target //:ok_binary up-to-date:
  bazel-bin/ok_binary
INFO: Elapsed time: 0.081s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action

Use the aspect to generate the expanded files in as a one-off build.

bazel build --config=expanded //:ok_binary
INFO: Analyzed target //:ok_binary (1 packages loaded, 2 targets configured).
INFO: Found 1 target...
Aspect @rules_rust//rust/private:expand.bzl%rust_expand_aspect of //:ok_binary up-to-date:
  bazel-bin/ok_binary.expand.rs
INFO: Elapsed time: 0.149s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action

Targeting tests is valid as well.

bazel build --config=expanded //:ok_test  
INFO: Analyzed target //:ok_test (0 packages loaded, 2 targets configured).
INFO: Found 1 target...
Aspect @rules_rust//rust/private:expand.bzl%rust_expand_aspect of //:ok_test up-to-date:
  bazel-bin/test-397521499/ok_test.expand.rs
INFO: Elapsed time: 0.113s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action

Finally, manually wire up a rust_expand target explicitly if you want a target to build.

load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_expand")

rust_binary(
    name = "ok_binary",
    srcs = ["src/main.rs"],
    edition = "2021",
)

rust_expand(
    name = "ok_binary_expand",
    deps = [":ok_binary"],
)

bazel build //:ok_binary_expand
INFO: Analyzed target //:ok_binary_expand (0 packages loaded, 1 target configured).
INFO: Found 1 target...
Target //:ok_binary_expand up-to-date:
  bazel-bin/ok_binary.expand.rs
INFO: Elapsed time: 0.090s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action

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…source files.

UebelAndre

Thanks for working on this! I think this would be a set of very useful rules. Got some feedback for you.

Also, I'm not sure if this is something that should go in the rust package vs tools or util.
@freeformstu any strong feelings here?
@illicitonion @scentini any opinions?

UebelAndre · 2022-12-07T02:07:29Z

.bazelci/presubmit.yml

@@ -411,6 +411,16 @@ tasks:
      - "//..."
    test_targets:
      - "//..."
+  expand_examples_ubuntu2004:


Instead of adding a new example, would you be willing to some integration tests for this in test

As of #1671 you should be able to gain access to a nightly toolchain in the main repo via a transition on @rules_rust//rust/toolchain/channel

UebelAndre · 2022-12-07T02:10:03Z

rust/private/expand.bzl

+            ),
+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+        ),
+        "_extra_rustc_flag": attr.label(default = "//:extra_rustc_flag"),


small nit:

Suggested change

"_extra_rustc_flag": attr.label(default = "//:extra_rustc_flag"),

"_extra_rustc_flag": attr.label(

default = Label("//:extra_rustc_flag"),

),

UebelAndre · 2022-12-07T02:10:25Z

rust/private/expand.bzl

+            default = Label("@bazel_tools//tools/cpp:current_cc_toolchain"),
+        ),
+        "_extra_rustc_flag": attr.label(default = "//:extra_rustc_flag"),
+        "_extra_rustc_flags": attr.label(default = "//:extra_rustc_flags"),


small nit:

Suggested change

"_extra_rustc_flags": attr.label(default = "//:extra_rustc_flags"),

"_extra_rustc_flags": attr.label(

default = Label("//:extra_rustc_flags"),

),

UebelAndre · 2022-12-07T02:11:44Z

rust/private/expand.bzl

+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""A module defining Rust expansion rules"""


Could you expand this module header a bit? I think it'd be nice to have some of the context currently in examples/expand/README.md here so we could render the docs for folks with the rest of rules_rust docs.

UebelAndre · 2022-12-07T02:13:28Z

rust/private/expand.bzl

+
+    return target[rust_common.crate_info]
+
+def _expand_aspect_impl(target, ctx):


small nit:

Suggested change

def _expand_aspect_impl(target, ctx):

def _rust_expand_aspect_impl(target, ctx):

I think it's nice to have the rule name be in the implementation function name.
e.g. The implementation of rust_binary is _rust_binary_impl.

UebelAndre · 2022-12-07T02:15:31Z

rust/private/expand.bzl

+    if crate_info.is_test:
+        args.rustc_flags.add("--test")
+
+    expand_out = ctx.actions.declare_file(ctx.label.name + ".expand.rs", sibling = crate_info.output)


Is all source code expanded into one file?

UebelAndre · 2022-12-07T02:16:20Z

rust/private/expand.bzl

+)
+```
+
+Then the targets can be expanded with the following command:


could you add a small snippet of how someone might inspect the generated source after running this?

scentini · 2022-12-16T16:03:04Z

What is the use case for the rust_expand rule? I would expect expanding the macros makes sense for debug purposes only, and for that the --config=expand should work well on the command line.

UebelAndre · 2023-12-25T20:04:03Z

Closing in favor of #2356

@freeformstu

Proposal for #1642 Duplicates #1643 (special thanks to @freeformstu) ### Summary Rustc can be used to expand all macros so that you can inspect the generated source files easier. This feature is enabled via `-Zunpretty={mode}`. The `-Z` flag is only available in the nightly version of `rustc` (rust-lang/rust#43364). ### Unprettying Build and test your targets normally. ``` bazel build //:ok_binary INFO: Analyzed target //:ok_binary (0 packages loaded, 0 targets configured). INFO: Found 1 target... Target //:ok_binary up-to-date: bazel-bin/ok_binary INFO: Elapsed time: 0.081s, Critical Path: 0.00s INFO: 1 process: 1 internal. INFO: Build completed successfully, 1 total action ``` Use the aspect to generate the expanded files in as a one-off build. (`.bazelrc`) ``` # Enable unpretty for all targets in the workspace build:unpretty --aspects=@rules_rust//rust:defs.bzl%rust_unpretty_aspect build:unpretty --output_groups=+rust_unpretty # `unpretty` requires the nightly toolchain. See tracking issue: # rust-lang/rust#43364 build:unpretty --@rules_rust//rust/toolchain/channel=nightly ``` ``` bazel build --config=unpretty //:ok_binary INFO: Analyzed target //:ok_binary (1 packages loaded, 2 targets configured). INFO: Found 1 target... Aspect @rules_rust//rust/private:unpretty.bzl%rust_unpretty_aspect of //:ok_binary up-to-date: bazel-bin/ok_binary.expand.rs INFO: Elapsed time: 0.149s, Critical Path: 0.00s INFO: 1 process: 1 internal. INFO: Build completed successfully, 1 total action ``` Targeting tests is valid as well. ``` bazel build --config=unpretty //:ok_test INFO: Analyzed target //:ok_test (0 packages loaded, 2 targets configured). INFO: Found 1 target... Aspect @rules_rust//rust/private:unpretty.bzl%rust_expand_aspect of //:ok_test up-to-date: bazel-bin/test-397521499/ok_test.expand.rs INFO: Elapsed time: 0.113s, Critical Path: 0.00s INFO: 1 process: 1 internal. INFO: Build completed successfully, 1 total action ``` Finally, manually wire up a `rust_unpretty` target explicitly if you want a target to build. This rule is unique compared to the aspect in that it forces a transition to a nightly toolchain so that `-Zunpretty` can be used. ```starlark load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_unpretty") rust_binary( name = "ok_binary", srcs = ["src/main.rs"], edition = "2021", ) rust_unpretty( name = "ok_binary_expand", deps = [":ok_binary"], ) ``` ``` bazel build //:ok_binary_expand INFO: Analyzed target //:ok_binary_expand (0 packages loaded, 1 target configured). INFO: Found 1 target... Target //:ok_binary_expand up-to-date: bazel-bin/ok_binary.expand.rs INFO: Elapsed time: 0.090s, Critical Path: 0.00s INFO: 1 process: 1 internal. INFO: Build completed successfully, 1 total action ```

freeformstu force-pushed the dev/expand branch 2 times, most recently from ac82745 to 0706e35 Compare November 9, 2022 03:41

Add rust_expand and rust_expand_aspect for generating macro expanded …

1f3787b

…source files.

freeformstu force-pushed the dev/expand branch from 0706e35 to 1f3787b Compare November 9, 2022 05:20

UebelAndre self-requested a review November 11, 2022 03:00

UebelAndre changed the title ~~Add rust_expand and rust_expand_aspect for generating macro expanded source files.~~ Add rust_expand and rust_expand_aspect for generating macro expanded source files. Dec 7, 2022

UebelAndre requested changes Dec 7, 2022

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UebelAndre mentioned this pull request Dec 25, 2023

Added rust_unpretty_aspect and rust_unpretty rules #2356

Merged

UebelAndre closed this Dec 25, 2023

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Add `rust_expand` and `rust_expand_aspect` for generating macro expanded source files. #1643

Add `rust_expand` and `rust_expand_aspect` for generating macro expanded source files. #1643

freeformstu commented Nov 9, 2022 •

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scentini commented Dec 16, 2022

UebelAndre commented Dec 25, 2023


		return target[rust_common.crate_info]

		def _expand_aspect_impl(target, ctx):

	def _expand_aspect_impl(target, ctx):
	def _rust_expand_aspect_impl(target, ctx):

Add rust_expand and rust_expand_aspect for generating macro expanded source files. #1643

Add rust_expand and rust_expand_aspect for generating macro expanded source files. #1643

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scentini commented Dec 16, 2022

UebelAndre commented Dec 25, 2023

Add `rust_expand` and `rust_expand_aspect` for generating macro expanded source files. #1643

Add `rust_expand` and `rust_expand_aspect` for generating macro expanded source files. #1643

freeformstu commented Nov 9, 2022 •

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