Fix ICE when combining #[eii] with #[core::contracts::ensures]#153796

GokhanKabar · 2026-03-12T23:05:40Z

Builtin attribute macros like #[eii] generate AST items programmatically without collected tokens. When another attribute macro was present on the same item, the compiler would panic in TokenStream::from_ast() trying to tokenize the generated items during subsequent attribute expansion.

Generate fake token streams (via pretty-print and re-parse) for Item and ForeignItem nodes that lack collected tokens, following the existing pattern used for Crate and out-of-line modules.

rustbot · 2026-03-12T23:05:43Z

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

cc @fmease

rustbot · 2026-03-12T23:05:45Z

r? @davidtwco

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Builtin attribute macros like #[eii] generate AST items programmatically without collected tokens. When another attribute macro was present on the same item, the compiler would panic in TokenStream::from_ast() trying to tokenize the generated items during subsequent attribute expansion. Generate fake token streams (via pretty-print and re-parse) for Item and ForeignItem nodes that lack collected tokens, following the existing pattern used for Crate and out-of-line modules.

Kivooeo · 2026-03-13T06:31:36Z

r? jdonszelmann

jdonszelmann · 2026-04-05T10:13:13Z

tests/ui/eii/ice_contract_attr_on_eii_generated_item.rs

+//~^ ERROR contract annotations is only supported in functions with bodies
+//~| ERROR contract annotations can only be used on functions
+fn implementation() {}
+//~^ ERROR cannot find value `implementation` in module `self`


this error is sus to me. I think this also needs a test of a real EII, that we call at runtime (// @run-pass) to make sure this works. I have a suspicion that the roundtrip of pretty printing destroys the EII link here.

i.e. pretty printing and reparsing doesn't preserve the fact that the EII has an implementation.

jdonszelmann

I think this is subtly incorrect, see above comments. Could you add the appropriate tests to prove that it is correct, and if not, I'm happy to talk about how we should fix this cause this is a real issue :)

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rustbot · 2026-04-05T10:14:12Z

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

…ass test When a function has `eii_impls` set (via `eii_shared_macro`), the `#[hello]` attribute is consumed from `node.attrs()`. A subsequent `AttrProcMacro` expander like `contracts::requires` calls `item.to_tokens()` which uses the current `node.attrs()` — so `#[hello]` is missing from the token stream. After the roundtrip and `parse_ast_fragment`, the new AST item has empty `eii_impls` and the EII link is broken. Fix this by using `fake_token_stream_for_item` when the item is a function with non-empty `eii_impls`. The pretty-printer re-emits `eii_impls` as `#[hello]` in `print_fn_full`, which survives the roundtrip and gets re-expanded by `eii_shared_macro` on the resulting item. Add a run-pass test to verify EII + contract annotation works correctly at runtime.

GokhanKabar · 2026-04-07T13:28:27Z

I think this is subtly incorrect, see above comments. Could you add the appropriate tests to prove that it is correct, and if not, I'm happy to talk about how we should fix this cause this is a real issue :)

View changes since this review

You were right the pretty-print roundtrip does break the EII link.

What happens : when #[hello] (via eii_shared_macro, a LegacyAttr) runs first, it adds to f.eii_impls and returns the item. The #[hello] attribute is now consumed from node.attrs(). When contracts::requires (an AttrProcMacro) runs next,
item.to_tokens() uses node.attrs() (empty) + the stored body tokens #[hello] is gone. After the token roundtrip and parse_ast_fragment, the new AST item has empty eii_impls and the EII link is broken.

The fix : the pretty-printer already re-emits eii_impls as #[hello] in print_fn_full. So when a function has non-empty eii_impls, I use fake_token_stream_for_item instead of item.to_tokens(). This puts #[hello] back in the token stream,
which survives the roundtrip and gets re-expanded by eii_shared_macro on the contracts-wrapped function.

Added a run-pass test (eii_impl_with_contract.rs) to prove it works at runtime.

…erated_item test The previous test used `fn implementation() {}` with a body, which caused `generate_default_impl` to generate a `const _: () = { fn implementation() {} }` item containing `self::implementation`. On Linux (aarch64-gnu-llvm-21), the resolver's `suggest_ident_hidden_by_hygiene` emitted an extra help span on the resulting E0425 error that did not appear on macOS, causing a stderr mismatch. Switch the declaration to `fn implementation();` (no body) so that `generate_default_impl` is not called and no `self::implementation` path is emitted. The test still validates that `#[eii]` + `#[core::contracts::ensures]` produces graceful errors instead of an ICE, via the two contract-annotation errors on the generated foreign item.

jdonszelmann · 2026-04-10T09:39:19Z

@bors r+ rollup

rust-bors · 2026-04-10T09:39:23Z

📌 Commit 48eced8 has been approved by jdonszelmann

It is now in the queue for this repository.

…-eii-attr-expansion, r=jdonszelmann Fix ICE when combining #[eii] with #[core::contracts::ensures] Fixes rust-lang#153745 Builtin attribute macros like #[eii] generate AST items programmatically without collected tokens. When another attribute macro was present on the same item, the compiler would panic in TokenStream::from_ast() trying to tokenize the generated items during subsequent attribute expansion. Generate fake token streams (via pretty-print and re-parse) for Item and ForeignItem nodes that lack collected tokens, following the existing pattern used for Crate and out-of-line modules.

…uwer Rollup of 2 pull requests Successful merges: - #153796 (Fix ICE when combining #[eii] with #[core::contracts::ensures]) - #155065 (error on invalid macho section specifier)

…-eii-attr-expansion, r=jdonszelmann Fix ICE when combining #[eii] with #[core::contracts::ensures] Fixes rust-lang#153745 Builtin attribute macros like #[eii] generate AST items programmatically without collected tokens. When another attribute macro was present on the same item, the compiler would panic in TokenStream::from_ast() trying to tokenize the generated items during subsequent attribute expansion. Generate fake token streams (via pretty-print and re-parse) for Item and ForeignItem nodes that lack collected tokens, following the existing pattern used for Crate and out-of-line modules.

…uwer Rollup of 8 pull requests Successful merges: - #155047 (Always exhaustively match on typing mode) - #155080 (Simplify `try_load_from_disk_fn`.) - #152384 (Restrict EII declarations to functions at lowering time) - #153796 (Fix ICE when combining #[eii] with #[core::contracts::ensures]) - #154369 (Fix `pattern_from_macro_note` for bit-or expr) - #155027 ( Rename some more of our internal `#[rustc_*]` TEST attributes) - #155031 (delegation: fix unelided lifetime ICE, refactoring of GenericArgPosition) - #155040 (Fix code block whitespace handling in Markdown)

Rollup merge of #153796 - GokhanKabar:fix-ice-missing-tokens-eii-attr-expansion, r=jdonszelmann Fix ICE when combining #[eii] with #[core::contracts::ensures] Fixes #153745 Builtin attribute macros like #[eii] generate AST items programmatically without collected tokens. When another attribute macro was present on the same item, the compiler would panic in TokenStream::from_ast() trying to tokenize the generated items during subsequent attribute expansion. Generate fake token streams (via pretty-print and re-parse) for Item and ForeignItem nodes that lack collected tokens, following the existing pattern used for Crate and out-of-line modules.

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 12, 2026

rustbot assigned davidtwco Mar 12, 2026

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GokhanKabar force-pushed the fix-ice-missing-tokens-eii-attr-expansion branch from 2ebb669 to 8a26389 Compare March 12, 2026 23:09

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GokhanKabar force-pushed the fix-ice-missing-tokens-eii-attr-expansion branch from 8a26389 to 99821e1 Compare March 12, 2026 23:17

rustbot assigned jdonszelmann and unassigned davidtwco Mar 13, 2026

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GokhanKabar force-pushed the fix-ice-missing-tokens-eii-attr-expansion branch from 3c67b0c to 48eced8 Compare April 8, 2026 08:44

GokhanKabar requested a review from jdonszelmann April 8, 2026 17:32

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JonathanBrouwer mentioned this pull request Apr 10, 2026

Rollup of 2 pull requests #155090

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This was referenced Apr 10, 2026

Rollup of 5 pull requests #155094

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Rollup of 8 pull requests #155099

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rust-bors bot merged commit 45223fe into rust-lang:main Apr 10, 2026
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