Lex lifetimes as identifiers, recover from emoji and emit appropriate error by estebank · Pull Request #153893 · rust-lang/rust

estebank · 2026-03-15T01:24:54Z

Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start.

error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦`
  --> $DIR/emoji-in-lifetime.rs:1:22
   |
LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>(
   |                      ^^^^^^^^^^^^^^^^^^^^^

Address #141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

rustbot · 2026-03-15T01:24:58Z

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

cc @fmease

rustbot · 2026-03-15T01:25:00Z

r? @jdonszelmann

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Kivooeo · 2026-03-15T12:57:59Z

        self.bump();
-        self.eat_while(is_id_continue);
+        self.eat_while(|c| {
+            let is_emoji = !c.is_ascii() && c.is_emoji_char();


can we possibly create a function or a method for this, i see this logic is using in two places, maybe something like self.is_emoji() would be better approach?

fmease · 2026-03-15T13:01:58Z

+                    if has_emoji {
+                        self.dcx().struct_span_err(span, "lifetimes cannot contain emoji").emit();
+                    }


Why not make use of the preexisting ParseSess.bad_unicode_identifiers & rustc_interface::passes infrastructure?

("lifetime"¹ tokens are a kind of identifier)

Footnotes

Strictly speaking "ticked identifiers" because they don't just represent lifetimes but also labels which have a distinct grammar (e.g., 'static is not a syntactically valid label but it is a lexically valid ~~"lifetime"~~ ticked identifier) ↩

The main reason to not do that is to still leverage the 'blah' recovery machinery. Here we are in a situation where we have to either choose one case to have nicer output than the other, or find a good way to unify both checks.

rustbot · 2026-03-18T18:38:25Z

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

Veykril

rust-analyzer side

View changes since this review

jdonszelmann · 2026-03-30T15:11:03Z

I agree with esteban for the nicer suggestions here, that's probably worth it. Sorry it took me a while, but lgtm.

@bors r=me,veykril rollup

rust-bors · 2026-03-30T15:11:09Z

📌 Commit 4f1676d has been approved by me,veykril

It is now in the queue for this repository.

⚠️ The following reviewer(s) could not be found: me

fmease · 2026-03-30T15:25:13Z

@bors r=jdonszelmann,Veykril

rust-bors · 2026-03-30T15:25:16Z

📌 Commit 4f1676d has been approved by jdonszelmann,Veykril

It is now in the queue for this repository.

…lmann,Veykril Lex lifetimes as identifiers, recover from emoji and emit appropriate error Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦` --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Address rust-lang#141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

Rollup of 7 pull requests Successful merges: - #142659 (compiler-builtins: Clean up features) - #153574 (Avoid ICE when param-env normalization leaves unresolved inference variables) - #153648 (Fix EII function aliases eliminated by LTO) - #153790 (Fix regression when dealing with generics/values with unresolved inference) - #153893 (Lex lifetimes as identifiers, recover from emoji and emit appropriate error) - #153980 (refactor: move doc(rust_logo) check to parser) - #154551 (Skip suggestions pointing to macro def for assert_eq)

rustbot · 2026-10-26T16:20:52Z

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.

estebank · 2026-10-26T16:25:08Z

I've only made one change: reverted the field name change from invalid back to starts_with_number. The meaning of the field has changed to include emoji, but we need to introduce that name change in tandem between rust-analyzer and rustc for rustc_lexer. This PR adjusts ra to also consider it with the same meaning (emitting an appropriate message), and we should have a subsequent PR to adjust the name of the field once we figure out what the right cross-repo dance is to do that.

Lex and parse emoji in lifetimes, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: lifetimes cannot contain emoji --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Unify lifetime and identifier parsing. Use `bad_unicode_identifiers` for lifetimes.

estebank · 2026-10-26T23:33:57Z

Approving as per #153893 (comment)

@bors r=jdonszelmann,Veykril

rust-bors · 2026-10-26T23:34:01Z

📌 Commit 21f918c has been approved by jdonszelmann,Veykril

It is now in the queue for this repository.

…lmann,Veykril Lex lifetimes as identifiers, recover from emoji and emit appropriate error Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦` --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Address rust-lang#141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

Rollup of 8 pull requests Successful merges: - #159540 (Enable statx on all Linux targets and short-circuit it for musl) - #164168 (Add tests for unsoundness involving alias liveness) - #164608 (core: Constify `resumable_breakpoint` and re-export it in `std`) - #164787 (cg_llvm: Use an invariant lifetime brand for LLVM contexts ) - #164966 (x86-64-linux-gnu seems to have working f128 now) - #153893 (Lex lifetimes as identifiers, recover from emoji and emit appropriate error) - #164895 (Disable recovery when attribute parser shouldn't emit) - #165004 (docs: Nitpick change in `HashMap`'s `.insert_entry()` doc example)

…lmann,Veykril Lex lifetimes as identifiers, recover from emoji and emit appropriate error Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦` --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Address rust-lang#141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

Rollup of 8 pull requests Successful merges: - #164168 (Add tests for unsoundness involving alias liveness) - #164608 (core: Constify `resumable_breakpoint` and re-export it in `std`) - #164787 (cg_llvm: Use an invariant lifetime brand for LLVM contexts ) - #164851 (Add behavior tests for `Arc` and `Rc`) - #164966 (x86-64-linux-gnu seems to have working f128 now) - #153893 (Lex lifetimes as identifiers, recover from emoji and emit appropriate error) - #164895 (Disable recovery when attribute parser shouldn't emit) - #165004 (docs: Nitpick change in `HashMap`'s `.insert_entry()` doc example)

Rollup of 9 pull requests Successful merges: - #164168 (Add tests for unsoundness involving alias liveness) - #164608 (core: Constify `resumable_breakpoint` and re-export it in `std`) - #164787 (cg_llvm: Use an invariant lifetime brand for LLVM contexts ) - #164966 (x86-64-linux-gnu seems to have working f128 now) - #153893 (Lex lifetimes as identifiers, recover from emoji and emit appropriate error) - #164848 (Add `strict_` methods to `NonZero`) - #164895 (Disable recovery when attribute parser shouldn't emit) - #164963 (fd-views: enable test on Miri) - #165004 (docs: Nitpick change in `HashMap`'s `.insert_entry()` doc example)

…lmann,Veykril Lex lifetimes as identifiers, recover from emoji and emit appropriate error Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦` --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Address rust-lang#141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

Rollup of 9 pull requests Successful merges: - #164168 (Add tests for unsoundness involving alias liveness) - #164608 (core: Constify `resumable_breakpoint` and re-export it in `std`) - #164787 (cg_llvm: Use an invariant lifetime brand for LLVM contexts ) - #164966 (x86-64-linux-gnu seems to have working f128 now) - #153893 (Lex lifetimes as identifiers, recover from emoji and emit appropriate error) - #164848 (Add `strict_` methods to `NonZero`) - #164895 (Disable recovery when attribute parser shouldn't emit) - #164963 (fd-views: enable test on Miri) - #165004 (docs: Nitpick change in `HashMap`'s `.insert_entry()` doc example)

Rollup merge of #153893 - estebank:emoji-lifetime, r=jdonszelmann,Veykril Lex lifetimes as identifiers, recover from emoji and emit appropriate error Lex and parse emoji in lifetimes by using the identifier logic, and disallow them in the parser with a hard error. Allow emoji to start a lifetime name even if they are not XID_Start. ``` error: identifiers cannot contain emoji: `'🐛🐛🐛family👨👩👧👦` --> $DIR/emoji-in-lifetime.rs:1:22 | LL | fn bad_lifetime_name<'🐛🐛🐛family👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ``` Address #141081 (but we could provide more information in the diagnostic, pointing at the specific chars, providing a link to the reference on identifiers and/or some other extra information).

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 15, 2026

rustbot assigned jdonszelmann Mar 15, 2026

estebank mentioned this pull request Mar 15, 2026

Confusing error when using non-XID_Start characters in lifetime names #141081

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