Remove ProcMacro enum from proc macro ABI by bjorn3 · Pull Request #157571 · rust-lang/rust

bjorn3 · 2026-06-07T12:05:03Z

Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of.

r? @petrochenkov cc @cyrgani

rustbot · 2026-06-07T12:05:06Z

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

bjorn3 · 2026-06-07T12:05:41Z

 extern crate rustc_proc_macro;
+extern crate rustc_session;
+extern crate rustc_span;
+extern crate rustc_target;


This is why I did rust-lang/rust-analyzer#22500

View changes since the review

petrochenkov · 2026-06-09T12:00:36Z

I'm surprised that we don't have a test doing -Zunpretty=expanded on a proc macro crate, so that all the generated proc macro harness is visible.
Could you perhaps add one?
(Before the changes from this PR and containing all 3 kinds of proc macros, and with helper attributes too.)

bjorn3 · 2026-06-09T12:18:11Z

tests/ui/proc-macro/quote/debug.rs is already a test that uses -Zunpretty=expanded, but I don't mind adding a dedicated test for it.

petrochenkov · 2026-06-09T12:24:55Z

Otherwise LGTM.
@rustbot author

Incorrect types can't cause unsafety and making it untyped will make it easier to get rid of the ProcMacro enum in the proc-macro ABI.

Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of.

rustbot · 2026-06-09T13:41:50Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

bjorn3 · 2026-06-09T13:42:28Z

Added test.

petrochenkov · 2026-06-09T15:32:44Z

Thanks!
@bors r+

rust-bors · 2026-06-09T15:32:47Z

📌 Commit 993bda7 has been approved by petrochenkov

It is now in the queue for this repository.

@petrochenkov

…trochenkov Remove ProcMacro enum from proc macro ABI Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of. r? @petrochenkov cc @cyrgani

@petrochenkov

…trochenkov Remove ProcMacro enum from proc macro ABI Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of. r? @petrochenkov cc @cyrgani

Rollup of 18 pull requests Successful merges: - #152852 (Remove driver_lint_caps) - #157166 (Change type of async context parameter after state transform.) - #157335 (bootstrap: Handle dotted table keys when parsing bootstrap.toml) - #157503 (Disable `tests/debuginfo/pretty-std.rs` `OsString` cdb check) - #157571 (Remove ProcMacro enum from proc macro ABI) - #148183 (rustdoc: Test & document `test_harness` code block attribute) - #153847 (Fix marker trait winnowing depending on impl order) - #156067 (Fix async drop glue for Box<T>) - #156399 (fix improper ctypes in Znext solver) - #157338 (Make `Literal::byte_character_value` work with bytes as well) - #157410 (Implement rustc_public::CrateDef{,Type} for FieldDef) - #157605 (Arg splat experiment - syntax impl) - #157630 (Add multibyte JSON diagnostic regression test) - #157633 (Reorder `impl` restriction rendering and add bottom margin) - #157642 (Report duplicate relaxed bounds during ast lowering) - #157652 (fix doc for unicode normalization faq on `casefold` APIs) - #157661 (Update to ar_archive_writer v0.5.2) - #157668 (Add test for matches in `rustc_must_match_exhaustively`) Failed merges: - #157670 (Rename `errors.rs` file to `diagnostics.rs` (4/N))

Rollup of 17 pull requests Successful merges: - #157166 (Change type of async context parameter after state transform.) - #157335 (bootstrap: Handle dotted table keys when parsing bootstrap.toml) - #157503 (Disable `tests/debuginfo/pretty-std.rs` `OsString` cdb check) - #157571 (Remove ProcMacro enum from proc macro ABI) - #148183 (rustdoc: Test & document `test_harness` code block attribute) - #153847 (Fix marker trait winnowing depending on impl order) - #156067 (Fix async drop glue for Box<T>) - #156399 (fix improper ctypes in Znext solver) - #157338 (Make `Literal::byte_character_value` work with bytes as well) - #157410 (Implement rustc_public::CrateDef{,Type} for FieldDef) - #157605 (Arg splat experiment - syntax impl) - #157630 (Add multibyte JSON diagnostic regression test) - #157633 (Reorder `impl` restriction rendering and add bottom margin) - #157642 (Report duplicate relaxed bounds during ast lowering) - #157652 (fix doc for unicode normalization faq on `casefold` APIs) - #157661 (Update to ar_archive_writer v0.5.2) - #157668 (Add test for matches in `rustc_must_match_exhaustively`) Failed merges: - #157670 (Rename `errors.rs` file to `diagnostics.rs` (4/N))

@petrochenkov

Rollup merge of #157571 - bjorn3:proc_macro_refactors6, r=petrochenkov Remove ProcMacro enum from proc macro ABI Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of. r? @petrochenkov cc @cyrgani

Rollup of 17 pull requests Successful merges: - rust-lang/rust#157166 (Change type of async context parameter after state transform.) - rust-lang/rust#157335 (bootstrap: Handle dotted table keys when parsing bootstrap.toml) - rust-lang/rust#157503 (Disable `tests/debuginfo/pretty-std.rs` `OsString` cdb check) - rust-lang/rust#157571 (Remove ProcMacro enum from proc macro ABI) - rust-lang/rust#148183 (rustdoc: Test & document `test_harness` code block attribute) - rust-lang/rust#153847 (Fix marker trait winnowing depending on impl order) - rust-lang/rust#156067 (Fix async drop glue for Box<T>) - rust-lang/rust#156399 (fix improper ctypes in Znext solver) - rust-lang/rust#157338 (Make `Literal::byte_character_value` work with bytes as well) - rust-lang/rust#157410 (Implement rustc_public::CrateDef{,Type} for FieldDef) - rust-lang/rust#157605 (Arg splat experiment - syntax impl) - rust-lang/rust#157630 (Add multibyte JSON diagnostic regression test) - rust-lang/rust#157633 (Reorder `impl` restriction rendering and add bottom margin) - rust-lang/rust#157642 (Report duplicate relaxed bounds during ast lowering) - rust-lang/rust#157652 (fix doc for unicode normalization faq on `casefold` APIs) - rust-lang/rust#157661 (Update to ar_archive_writer v0.5.2) - rust-lang/rust#157668 (Add test for matches in `rustc_must_match_exhaustively`) Failed merges: - rust-lang/rust#157670 (Rename `errors.rs` file to `diagnostics.rs` (4/N))

JonathanBrouwer · 2026-06-13T10:43:13Z

@rust-timer build 3980b37

rust-timer · 2026-06-13T18:42:27Z

Finished benchmarking commit (3980b37): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	2
Improvements ✅ (primary)	-0.3%	[-0.3%, -0.2%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.3%	[-0.3%, -0.2%]	2

Max RSS (memory usage)

Results (primary -2.1%, secondary -0.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.0%	[1.1%, 2.5%]	4
Improvements ✅ (primary)	-2.1%	[-2.3%, -1.9%]	3
Improvements ✅ (secondary)	-2.5%	[-3.7%, -0.4%]	6
All ❌✅ (primary)	-2.1%	[-2.3%, -1.9%]	3

Cycles

This perf run didn't have relevant results for this metric.

Binary size

Results (primary 0.0%, secondary 0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.1%]	10
Regressions ❌ (secondary)	0.0%	[0.0%, 0.1%]	12
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.1%]	10

Bootstrap: 525.47s -> 518.733s (-1.28%)
Artifact size: 400.80 MiB -> 401.36 MiB (0.14%)

rustbot assigned petrochenkov Jun 7, 2026

bjorn3 commented Jun 7, 2026

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 9, 2026

bjorn3 added 4 commits June 9, 2026 15:27

Add snapshot test for proc macro decls array

6be73e2

Make proc_macro Client untyped

67c4850

Incorrect types can't cause unsafety and making it untyped will make it easier to get rid of the ProcMacro enum in the proc-macro ABI.

Remove ProcMacro enum from proc macro ABI

7edb1c0

Instead encode this information in the crate metadata. This helps shrink the proc-macro ABI to just the parts necessary for transmitting raw bytes to perform RPC on top of.

Fix rust-analyzer-proc-macro-srv

993bda7

bjorn3 force-pushed the proc_macro_refactors6 branch from 1c79135 to 993bda7 Compare June 9, 2026 13:41

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 9, 2026

GuillaumeGomez mentioned this pull request Jun 9, 2026

Rollup of 15 pull requests #157673

Closed

jhpratt mentioned this pull request Jun 9, 2026

Rollup of 18 pull requests #157679

Closed

jhpratt mentioned this pull request Jun 9, 2026

Rollup of 17 pull requests #157683

Merged

rust-bors Bot merged commit 20080dc into rust-lang:main Jun 10, 2026
12 checks passed

rustbot added this to the 1.98.0 milestone Jun 10, 2026

bjorn3 deleted the proc_macro_refactors6 branch June 10, 2026 08:48

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rust-timer commented Jun 13, 2026

Overall result: ❌✅ regressions and improvements - no action needed

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