fixed generics of crate node ICE by enthropy7 · Pull Request #153615 · rust-lang/rust

enthropy7 · 2026-03-09T16:00:33Z

when note_and_explain_type_err is called during dyn-compatibility checking, the body_owner_def_id can be CRATE_DEF_ID because ObligationCause::dummy() uses it as a placeholder when there is no real body owner. calling generics_of on CRATE_DEF_ID caused an ICE because the crate root is a module and modules don't have generics. the fix guards all generics_of call sites by checking whether body_owner_def_id is CRATE_DEF_ID before attempting to look up generics, and skips the type parameter span labeling in that case.

i also added regression test with original ice reproduce

fixes #152335

rustbot · 2026-03-09T16:00:41Z

r? @fee1-dead

rustbot has assigned @fee1-dead.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler
compiler expanded to 69 candidates
Random selection from 14 candidates

fee1-dead

I think overall this is not pretty fool-proof (what if someone else decides to call tcx.generics_of(body_owner_def_id) down the line, in the function or somewhere else?) and also requires quite some involved changes for an ICE that doesn't happen quite often.

I wonder whether we should simply return and not attempt to add additional information if the obligation cause is dummy.

I wonder whether we can try to make the original obligation cause not dummy.

View changes since this review

fee1-dead · 2026-03-29T05:18:56Z

+                        if !tcx.is_impl_trait_in_trait(proj.def_id) && body_generics.is_some() =>
                    {
-                        let param = tcx.generics_of(body_owner_def_id).type_param(p, tcx);
+                        let param = body_generics.unwrap().type_param(p, tcx);


Suggested change

if !tcx.is_impl_trait_in_trait(proj.def_id) && body_generics.is_some() =>

{

let param = tcx.generics_of(body_owner_def_id).type_param(p, tcx);

let param = body_generics.unwrap().type_param(p, tcx);

if !tcx.is_impl_trait_in_trait(proj.def_id) && let Some(body_generics) = body_generics =>

{

let param = body_generics.type_param(p, tcx);

fee1-dead · 2026-03-29T05:21:21Z

-                        };
-                        if !sp.contains(p_span) {
-                            diag.span_label(p_span, format!("{expected}this type parameter"));
+                        if let Some(generics) = body_generics {


This should be (ty::Param(p), _) | (_, ty::Param(p)) if let Some(generics) = body_generics =>

rustbot · 2026-03-29T05:24:23Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

enthropy7 · 2026-03-29T06:22:25Z

ok so my first uproach won't work, i went with guarding generics_of call sites, as early return turned out too aggressive, it suppressed useful notes/helps for async blocks and closures that don't need generics at all.
guard in suggest_constraint for the same reason.

regarding making the obligation cause non-dummy: ObligationCause::dummy() comes from receiver_is_dispatchable in dyn_compatibility.rs, and there's no real body owner in that context, so I think guarding in error reporting is the right place for now.

rustbot · 2026-04-03T13:39:32Z

Some changes occurred in src/tools/compiletest

cc @jieyouxu

compiletest directives have been modified. Please add or update docs for the
new or modified directive in src/doc/rustc-dev-guide/.

rustbot · 2026-04-03T15:18:16Z

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.

enthropy7 · 2026-04-03T18:12:51Z

ok so, i completely changed approach. body_owner_def_id is now Option<DefId> throughout note_and_explain_type_err and all its helpers (suggest_constraint, expected_projection, point_at_associated_type). CRATE_DEF_ID check happens once at the call site in mod.rs, and the Option propagates naturally. compiler won't let anyone call generics_of without handling None first. in fact, during rebase a new generics_of(body_owner_def_id) call site had been added upstream, and it was immediately caught as a compile error rather than a silent ICE.

enthropy7 · 2026-04-03T18:13:01Z

@rustbot ready

fee1-dead · 2026-04-05T23:59:52Z

@bors r+

rust-bors · 2026-04-05T23:59:56Z

📌 Commit f1a4ae0 has been approved by fee1-dead

It is now in the queue for this repository.

Rollup of 4 pull requests Successful merges: - #152853 (deny-by-default & report in deps `uninhabited_static`) - #153615 (fixed generics of crate node ICE) - #154744 (Remove `Clone` impl for `StableHashingContext`.) - #154841 (add regression test for Redundant memory strores with mut parameters …)

Rollup merge of #153615 - enthropy7:fix-ice-generics-of-crate-node, r=fee1-dead fixed generics of crate node ICE when `note_and_explain_type_err` is called during dyn-compatibility checking, the `body_owner_def_id` can be `CRATE_DEF_ID` because `ObligationCause::dummy()` uses it as a placeholder when there is no real body owner. calling `generics_of `on `CRATE_DEF_ID `caused an ICE because the crate root is a module and modules don't have generics. the fix guards all `generics_of` call sites by checking whether `body_owner_def_id` is `CRATE_DEF_ID` before attempting to look up generics, and skips the type parameter span labeling in that case. i also added regression test with original ice reproduce fixes #152335

Rollup of 4 pull requests Successful merges: - rust-lang/rust#152853 (deny-by-default & report in deps `uninhabited_static`) - rust-lang/rust#153615 (fixed generics of crate node ICE) - rust-lang/rust#154744 (Remove `Clone` impl for `StableHashingContext`.) - rust-lang/rust#154841 (add regression test for Redundant memory strores with mut parameters …)

rustbot assigned fee1-dead Mar 9, 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 Mar 9, 2026

This comment has been minimized.

Sign in to view

fee1-dead requested changes Mar 29, 2026

View reviewed changes

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 29, 2026

rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Mar 29, 2026

This comment has been minimized.

Sign in to view

rustbot added the has-merge-commits PR has merge commits, merge with caution. label Apr 3, 2026

This comment has been minimized.

Sign in to view

rustbot removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. has-merge-commits PR has merge commits, merge with caution. labels Apr 3, 2026

fix ice generics of crate node

f1a4ae0

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 3, 2026

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 Apr 5, 2026

jhpratt mentioned this pull request Apr 6, 2026

Rollup of 4 pull requests #154862

Merged

rust-bors Bot merged commit 2aa5ef1 into rust-lang:main Apr 6, 2026
11 checks passed

rustbot added this to the 1.96.0 milestone Apr 6, 2026

blackms mentioned this pull request Apr 12, 2026

Handle Node::Crate in generics_of to prevent ICE #155192

Closed

Uh oh!

Uh oh!

Conversation

enthropy7 commented Mar 9, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Mar 9, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

fee1-dead left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

fee1-dead Mar 29, 2026

Choose a reason for hiding this comment

Uh oh!

fee1-dead Mar 29, 2026

Choose a reason for hiding this comment

Uh oh!

rustbot commented Mar 29, 2026

Uh oh!

enthropy7 commented Mar 29, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

rustbot commented Apr 3, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

rustbot commented Apr 3, 2026

Uh oh!

enthropy7 commented Apr 3, 2026

Uh oh!

enthropy7 commented Apr 3, 2026

Uh oh!

fee1-dead commented Apr 5, 2026

Uh oh!

rust-bors Bot commented Apr 5, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

enthropy7 commented Mar 9, 2026 •

edited by rustbot

Loading

fee1-dead left a comment •

edited by rustbot

Loading

enthropy7 commented Mar 29, 2026 •

edited

Loading