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

compiler/rustc_lexer/src/lib.rs

        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

compiler/rustc_parse/src/lexer/mod.rs

+                    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)

Zalathar · 2026-03-31T05:32:00Z

Failed in rollup: #154611 (comment)

@bors r-
@bors try jobs=dist-ohos-armv7

rust-bors · 2026-03-31T05:32:08Z

This pull request was unapproved.

This PR was contained in a rollup (#154611), which was unapproved.

Lex lifetimes as identifiers, recover from emoji and emit appropriate error try-job: dist-ohos-armv7

rust-bors · 2026-03-31T06:28:20Z

💔 Test for 8db3bb9 failed: CI. Failed job:

try - dist-ohos-armv7 (web logs, enhanced plaintext logs)

jdonszelmann · 2026-04-02T09:35:20Z

@rustbot author (I think a soft conlict?)

rustbot · 2026-04-02T09:35:24Z

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

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👨👩👧👦>( | ^^^^^^^^^^^^^^^^^^^^^ ```

rustbot · 2026-04-03T01:27:09Z

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

rustbot · 2026-04-03T01:27:12Z

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.

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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estebank force-pushed the emoji-lifetime branch from 8679628 to cf3c735 Compare March 15, 2026 03:59

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estebank force-pushed the emoji-lifetime branch from cf3c735 to a45ca0d Compare March 18, 2026 18:09

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estebank force-pushed the emoji-lifetime branch from a45ca0d to dfdc525 Compare March 18, 2026 18:11

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estebank changed the title ~~Lex lifetimes using emoji and emit appropriate error~~ Lex lifetimes as identifiers, recover from emoji and emit appropriate error Mar 19, 2026

Veykril approved these changes Mar 19, 2026

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tgross35 mentioned this pull request Mar 30, 2026

Rollup of 7 pull requests #154611

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rust-bors bot pushed a commit that referenced this pull request Mar 31, 2026

Auto merge of #153893 - estebank:emoji-lifetime, r=<try>

8db3bb9

Lex lifetimes as identifiers, recover from emoji and emit appropriate error try-job: dist-ohos-armv7

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estebank added 6 commits April 3, 2026 01:14

Unify lifetime and identifier parsing

c88dd47

Use bad_unicode_identifiers for lifetimes

976e042

Fix rust-analyzer

3f3adda

remove whitespace

5b589e3

fix test

3896a9f

estebank force-pushed the emoji-lifetime branch from 4f1676d to 6506956 Compare April 3, 2026 01:27

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estebank force-pushed the emoji-lifetime branch from 6506956 to 3896a9f Compare April 3, 2026 01:41

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