Detect missing `derive` on unresolved attribute even when not imported #142487

estebank · 2025-06-14T05:34:47Z

When encountering unresolved attributes, ensure the proc-macros for every crate in scope are added to the macro_map so that typos and missing derives are properly detected.

error: cannot find attribute `sede` in this scope
  --> $DIR/missing-derive-3.rs:20:7
   |
LL |     #[sede(untagged)]
   |       ^^^^
   |
help: the derive macros `Deserialize` and `Serialize` accept the similarly named `serde` attribute
   |
LL |     #[serde(untagged)]
   |         +

error: cannot find attribute `serde` in this scope
  --> $DIR/missing-derive-3.rs:14:7
   |
LL |     #[serde(untagged)]
   |       ^^^^^
   |
note: `serde` is imported here, but it is a crate, not an attribute
  --> $DIR/missing-derive-3.rs:4:1
   |
LL | extern crate serde;
   | ^^^^^^^^^^^^^^^^^^^
help: `serde` is an attribute that can be used by the derive macros `Deserialize` and `Serialize`, you might be missing a `derive` attribute
   |
LL + #[derive(Deserialize, Serialize)]
LL | enum B {
   |

Follow up to #134841. Fix #47608.

rustbot · 2025-06-14T05:34:52Z

r? @jieyouxu

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compiler/rustc_resolve/src/build_reduced_graph.rs

jieyouxu · 2025-06-14T10:25:12Z

r? compiler

compiler-errors · 2025-07-16T19:45:40Z

This needs a perf run firstly I think

@bors try parent=855e0fe46e68d94e9f6147531b75ac2d488c548e @rust-timer queue

compiler-errors · 2025-07-16T19:46:16Z

ugh, that will fail because bors1 doesn't know parents. I meant:

@bors2 try parent=855e0fe46e68d94e9f6147531b75ac2d488c548e @rust-timer queue

Detect missing `derive` on unresolved attribute even when not imported When encountering unresolved attributes, ensure the proc-macros for every crate in scope are added to the `macro_map` so that typos and missing `derive`s are properly detected. ``` error: cannot find attribute `sede` in this scope --> $DIR/missing-derive-3.rs:20:7 | LL | #[sede(untagged)] | ^^^^ | help: the derive macros `Deserialize` and `Serialize` accept the similarly named `serde` attribute | LL | #[serde(untagged)] | + error: cannot find attribute `serde` in this scope --> $DIR/missing-derive-3.rs:14:7 | LL | #[serde(untagged)] | ^^^^^ | note: `serde` is imported here, but it is a crate, not an attribute --> $DIR/missing-derive-3.rs:4:1 | LL | extern crate serde; | ^^^^^^^^^^^^^^^^^^^ help: `serde` is an attribute that can be used by the derive macros `Deserialize` and `Serialize`, you might be missing a `derive` attribute | LL + #[derive(Deserialize, Serialize)] LL | enum B { | ``` Follow up to #134841.

rust-bors · 2025-07-16T19:46:20Z

⌛ Trying commit d617a5b with merge 07b2f21…

To cancel the try build, run the command @bors2 try cancel.

rust-bors · 2025-07-16T22:00:56Z

☀️ Try build successful (CI)
Build commit: 07b2f21 (07b2f218801fa85db469fc131c97d08b0a40e9b9, parent: 855e0fe46e68d94e9f6147531b75ac2d488c548e)

rust-timer · 2025-07-16T23:10:38Z

Finished benchmarking commit (07b2f21): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@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)	0.4%	[0.4%, 0.5%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary -1.9%)

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)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-6.2%	[-6.2%, -6.2%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary 2.3%, 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)	2.3%	[2.1%, 2.4%]	2
Regressions ❌ (secondary)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.8%	[-3.8%, -3.8%]	1
All ❌✅ (primary)	2.3%	[2.1%, 2.4%]	2

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 464.604s -> 465.331s (0.16%)
Artifact size: 374.58 MiB -> 374.59 MiB (0.00%)

compiler-errors · 2025-08-14T17:02:47Z

r? petrochenkov maybe?

bors · 2025-08-15T13:20:55Z

☔ The latest upstream changes (presumably #145423) made this pull request unmergeable. Please resolve the merge conflicts.

petrochenkov · 2025-08-15T13:23:00Z

compiler/rustc_metadata/src/rmeta/decoder.rs

+        data.macros
+            .decode(CrateMetadataRef { cdata: self, cstore })
+            .map(|index| DefId { index, krate })
+            .collect()


Can return an iterator using gen { ... } instead of collecting, see examples in the same file.

That's a neat trick to deal with the lifetimes of the iterator, I didn't know about it. Can't wait for stable generators :)

petrochenkov · 2025-08-15T13:23:13Z

compiler/rustc_metadata/src/creader.rs

+    pub fn all_proc_macro_def_ids(&self) -> Vec<DefId> {
+        self.iter_crate_data()
+            .flat_map(|(krate, data)| data.proc_macros_for_crate(krate, self))
+            .collect()


Also can return an iterator.

petrochenkov · 2025-08-15T13:27:13Z

compiler/rustc_resolve/src/build_reduced_graph.rs

+    /// find them for suggestions.
+    pub(crate) fn register_macros_for_all_crates(&mut self) {
+        if self.all_crate_macros_already_registered {
+            return;


Nit: if !things_done { do_things(); things_done = true; } would look slightly better.

petrochenkov · 2025-08-15T13:27:50Z

compiler/rustc_resolve/src/lib.rs

@@ -1266,6 +1266,10 @@ pub struct Resolver<'ra, 'tcx> {

    mods_with_parse_errors: FxHashSet<DefId>,

+    /// Whether `Resolver::register_macros_for_all_crates` has been called once already, as we
+    /// don't need to run it more than once.
+    all_crate_macros_already_registered: bool,


Suggested change

all_crate_macros_already_registered: bool,

all_crate_macros_already_registered: bool = false,

``` error: cannot find attribute `sede` in this scope --> $DIR/missing-derive-3.rs:20:7 | LL | #[sede(untagged)] | ^^^^ | help: the derive macros `Deserialize` and `Serialize` accept the similarly named `serde` attribute | LL | #[serde(untagged)] | + error: cannot find attribute `serde` in this scope --> $DIR/missing-derive-3.rs:14:7 | LL | #[serde(untagged)] | ^^^^^ | note: `serde` is imported here, but it is a crate, not an attribute --> $DIR/missing-derive-3.rs:4:1 | LL | extern crate serde; | ^^^^^^^^^^^^^^^^^^^ help: `serde` is an attribute that can be used by the derive macros `Deserialize` and `Serialize`, you might be missing a `derive` attribute | LL + #[derive(Deserialize, Serialize)] LL | enum B { | ```

estebank · 2025-08-15T16:04:12Z

Addressed and squashed.

rustbot assigned jieyouxu Jun 14, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 14, 2025

estebank commented Jun 14, 2025

View reviewed changes

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rustbot assigned compiler-errors and unassigned jieyouxu Jun 14, 2025

estebank force-pushed the serde-attr-5 branch from d1699eb to 7f15e03 Compare July 1, 2025 20:55

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estebank force-pushed the serde-attr-5 branch from 7f15e03 to b519205 Compare July 3, 2025 18:52