Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro by sgasho · Pull Request #151596 · rust-lang/rust

sgasho · 2026-01-24T14:56:23Z

related: #150910

I fixed declare_passes macro to detect unregistered enum names

UI Results

+nightly --> before: no warnings
+stage1 --> after: detect SimplifyCfg as an unknown pass

rustbot · 2026-01-24T14:58:03Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

rustbot · 2026-01-24T14:58:05Z

r? @nnethercote

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nnethercote · 2026-01-26T22:07:28Z

Update: I changed my mind on this, see below.

This is a reasonable attempt at fixing the issue. But I wonder if it's just a band-aid over the real problem?

Every MIR pass module has a single pass within, except for simplify which has two: SimplifyCfg and SimplifyLocals. Why is that? Could we just split that module into simplify_cfg::SimplifyCfg and simplify_locals::SimplifyLocals? That would remove one layers of $( )? in the macro and I think solve #150910 for free?

The only downside is that this would break external tools relying on the current names. But this kind of API is not guaranteed to be stable, and the breakage is trivial to fix.

@saethlin, what do you think?

nnethercote · 2026-01-26T22:28:31Z

compiler/rustc_mir_transform/src/lib.rs

+}
+
+macro_rules! pass_names {
+    ($mod_name:ident : $pass_name:ident { $($ident:ident),* $(,)? }) => {


It would be useful to have a brief comment on each rule explaining the case being handled. I.e. the first rule deals with pass groups, the second with lone pass names.

And in this first rule, $pass_name would be better called $pass_group, and $ident would be better called $pass_name.

I fixed them in the commit below

fac135a

nnethercote

After looking some more, I think this change is ok. I don't like how the existing macro is structured, where sometimes the thing after the colon is a pass name and sometimes it's a pass group, but fixing that seems beyond the scope of this PR.

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nnethercote · 2026-01-26T22:33:51Z

r=me with the aforementioned renamings but I'll give @saethlin a chance to respond in case I'm overlooking anything.

nnethercote · 2026-01-26T22:46:45Z

cc @clubby789, who wrote this code.

clubby789

This LGTM as a fix, I might look at re-doing the macro in future to be more logical

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nnethercote · 2026-01-28T23:11:29Z

@sgasho: looks good. Can you squash the commits (there's no value in these particular commits being separate) and then we will be good to go.

saethlin · 2026-01-29T01:24:45Z

tests/ui/lint/invalid_value-polymorphic.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: --crate-type=lib -Zmir-enable-passes=+InstSimplify
+//@ compile-flags: --crate-type=lib -Zmir-enable-passes=+InstSimplify-before-inline


The fact that you had to change this is making a strong case for the value of this change.

saethlin · 2026-01-29T01:28:45Z

Every MIR pass module has a single pass within, except for simplify which has two: SimplifyCfg and SimplifyLocals. Why is that? Could we just split that module into simplify_cfg::SimplifyCfg and simplify_locals::SimplifyLocals?

I agree that breaking up the simplify module seems like a good idea. I've tripped over the fact that it doesn't have the same symmetry between pass name and module name many times.

I don't have a strong opinion on the implementation, macros always look like token soup to me, but this one is of reasonable size. I mostly just care that this fixes the footgun.

saethlin · 2026-01-29T01:29:15Z

@bors r=nnethercote,saethlin

rust-bors · 2026-01-29T01:29:18Z

📌 Commit 99591e6 has been approved by nnethercote,saethlin

It is now in the queue for this repository.

…arn, r=nnethercote,saethlin Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro related: rust-lang#150910 I fixed declare_passes macro to detect unregistered enum names ### UI Results +nightly --> before: no warnings +stage1 --> after: detect SimplifyCfg as an unknown pass <img width="591" height="199" alt="スクリーンショット 2026-01-24 23 53 41" src="https://github.com/user-attachments/assets/ddabaa58-b4c6-4e80-a3c9-f40d866db273" />

Rollup of 8 pull requests Successful merges: - #150474 (Tidy: detect ui tests subdirectory changes so `tests/ui/README.md` stays in sync) - #150572 (Improve move error diagnostic for `AsyncFn` closures) - #151596 (Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro) - #151802 (Make `QueryDispatcher::Qcx` an associated type) - #151559 ([rustdoc] Add a marker to tell users that there are hidden (deprecated) items in the search results) - #151665 (Fix contrast ratio for `Since` element in rustodoc dark theme) - #151798 (Update `askama` to `0.15.3`) - #151800 (Subscribe myself to translation diagnostics)

Rollup of 12 pull requests Successful merges: - #150474 (Tidy: detect ui tests subdirectory changes so `tests/ui/README.md` stays in sync) - #150572 (Improve move error diagnostic for `AsyncFn` closures) - #151596 (Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro) - #151802 (Make `QueryDispatcher::Qcx` an associated type) - #149110 (Implement `cast_slice` for raw pointer types) - #151559 ([rustdoc] Add a marker to tell users that there are hidden (deprecated) items in the search results) - #151665 (Fix contrast ratio for `Since` element in rustdoc dark theme) - #151785 (Stabilize feature(push_mut)) - #151798 (Update `askama` to `0.15.3`) - #151800 (Subscribe myself to translation diagnostics) - #151804 (Document, sort, and tweak spellcheck entries in `typos.toml`) - #151805 (Fix grammar in `env::current_exe()#Security`)

Rollup merge of #151596 - sgasho:150910_SimplifyCfg_passes_warn, r=nnethercote,saethlin Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro related: #150910 I fixed declare_passes macro to detect unregistered enum names ### UI Results +nightly --> before: no warnings +stage1 --> after: detect SimplifyCfg as an unknown pass <img width="591" height="199" alt="スクリーンショット 2026-01-24 23 53 41" src="https://github.com/user-attachments/assets/ddabaa58-b4c6-4e80-a3c9-f40d866db273" />

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 24, 2026

sgasho marked this pull request as ready for review January 24, 2026 14:58

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 24, 2026

rustbot assigned nnethercote Jan 24, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jan 24, 2026

sgasho mentioned this pull request Jan 24, 2026

-Zmir-enable-passes=+SimplifyCfg doesn't enable any passes and doesn't warn #150910

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sgasho changed the title ~~Fix -Zmir-enable-passes to detect unregistered enum names~~ Fix -Zmir-enable-passes to detect unregistered enum names in declare_passes macro Jan 24, 2026

nnethercote reviewed Jan 26, 2026

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clubby789 approved these changes Jan 27, 2026

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Fix -Zmir-enable-passes to detect unregistered enum names

99591e6

sgasho force-pushed the 150910_SimplifyCfg_passes_warn branch from fac135a to 99591e6 Compare January 29, 2026 00:02

saethlin reviewed Jan 29, 2026

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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-review Status: Awaiting review from the assignee but also interested parties. labels Jan 29, 2026

Zalathar mentioned this pull request Jan 29, 2026

Rollup of 8 pull requests #151803

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Zalathar mentioned this pull request Jan 29, 2026

Rollup of 12 pull requests #151809

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rust-bors bot merged commit 9f0483e into rust-lang:main Jan 29, 2026
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rustbot added this to the 1.95.0 milestone Jan 29, 2026

github-actions bot mentioned this pull request Jan 30, 2026

Toolchain upgrade to nightly-2026-01-30 flux-rs/flux#1345

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		@@ -1,4 +1,4 @@
		//@ compile-flags: --crate-type=lib -Zmir-enable-passes=+InstSimplify
		//@ compile-flags: --crate-type=lib -Zmir-enable-passes=+InstSimplify-before-inline

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sgasho commented Jan 24, 2026

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