Modify error message of importing inherent associated items when `#[feature(import_trait_associated_functions)]` is enabled by CoCo-Japan-pan · Pull Request #152611 · rust-lang/rust

CoCo-Japan-pan · 2026-02-14T12:13:10Z

This PR improves the diagnostic for importing inherent associated items from a struct or union when
#[feature(import_trait_associated_functions)] (#134691) is enabled.

Previously, this would result in a "not a module" error. This change provides a more specific error message clarifying that only trait associated items can be imported, while inherent associated items remain ineligible for import.

Enums are currently excluded from this change because their variants are valid import targets and require distinct handling.

rustbot · 2026-02-14T12:13:16Z

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madsmtm · 2026-02-26T10:41:50Z

tests/ui/imports/import-inherent-148009.rs

+//! and one trys to import inherent associated items, the error message is
+//! updated to reflect that only trait associated items can be imported.
+//!
+//! Regression test for <https://github.com/rust-lang/rust/issues/148009>.


I think you have to add further annotations to actually test the label? Something like //~| NOTE cannot import inherent associated items, only trait associated items IIRC?

Added a note NOTE cannot import inherent associated items, only trait associated items in fae6a31

madsmtm · 2026-02-26T10:43:00Z

compiler/rustc_resolve/src/ident.rs

-                                    res.article(),
-                                    res.descr()
-                                );
+                                // Excluding enums since their variants are valid import targets.


Could you add a test case for enums too? I'm not suuper convinced that we don't want a different error message there too, but perhaps I'm missing something?

For structs or unions, I think the :: syntax basically leads to associated items, while for enums, it will basically mean enum variants, and the current error for enums says that "there are no such variants", rather than "this is not a module".
Modifying here will overwrite "there are no such variants" errors, so I excluded it here. Maybe I should make it show both?

Right, enums are treated as-if they're modules, and you'll get a "no VariantName in EnumName" error pointing to the variant instead.

Which means I don't actually think that matching on DefKind::Enum would change anything? This diagnostic is never shown for enums?

But semantically, I think it makes sense to include DefKind::Enum (and DefKind::ForeignTy) in here, and change the comment to something like:

Suggested change

// Excluding enums since their variants are valid import targets.

// Show a different error message for items that can have associated items.

Import errors for enums seem to be handled in rustc_resolve/src/imports.rs, so I added a note there 4d5ce5d

madsmtm · 2026-02-26T10:46:26Z

compiler/rustc_resolve/src/ident.rs

+                                    "cannot import inherent associated items, only trait associated items".to_string()
+                                } else {
+                                    format!(
+                                        "`{ident}` is {} {}, not a module",


We should really be saying "not a module or trait" (or enum) when import_trait_associated_functions is enabled, shouldn't we?

Modified the error message to ..., not a module or a trait in 58374d7

rustbot · 2026-02-28T04:29:06Z

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.

CoCo-Japan-pan · 2026-02-28T05:50:52Z

@rustbot ready

fmease · 2026-03-05T09:58:44Z

compiler/rustc_resolve/src/ident.rs

-                                    res.descr()
+                                    res.descr(),
+                                    if import_inherent_item_error_flag {
+                                        " nor traits"


Suggested change

" nor traits"

" or a trait"

$ident is -> singular

(disclaimer: I'm L2) nor in this context (i.e., outside neither … nor …) is fine in colloquial speech but or is more correct. The not covers both nouns here, so it's "not {a module or a trait}" -(De Morgan)-> "{not a module} and {not a trait}".

Oops, my mistake. I'll push a fix shortly.

…ssociated items

…ns` is enabled

rustbot assigned madsmtm Feb 14, 2026

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 Feb 14, 2026

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madsmtm reviewed Feb 26, 2026

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madsmtm 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 Feb 26, 2026

CoCo-Japan-pan force-pushed the fix-148009 branch from 804233c to 88d46f8 Compare February 28, 2026 04:29

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Feb 28, 2026

fmease reviewed Mar 5, 2026

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CoCo-Japan-pan added 3 commits March 5, 2026 20:07

Modify the error message shown when a user tries to import inherent a…

58374d7

…ssociated items

Add note for enum import errors when `import_trait_associated_functio…

4d5ce5d

…ns` is enabled

Add UI tests for inherent associated item import attempts

fae6a31

CoCo-Japan-pan force-pushed the fix-148009 branch from 88d46f8 to fae6a31 Compare March 5, 2026 11:10

	// Excluding enums since their variants are valid import targets.
	// Show a different error message for items that can have associated items.

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CoCo-Japan-pan commented Feb 14, 2026 •

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