Revert "Don't recover lifetimes/labels containing emojis as character literals"

Reverts PR #108031
Fixes (doesnt close until beta backported) #109746

This reverts commit e3f9db5.
This reverts commit 98b82ae.
This reverts commit 380fa26.

Author: compiler-errors

compiler/rustc_errors/src/lib.rs

@@ -473,8 +473,6 @@ pub enum StashKey {
     /// When an invalid lifetime e.g. `'2` should be reinterpreted
     /// as a char literal in the parser
     LifetimeIsChar,
-    /// When an invalid lifetime e.g. `'🐱` contains emoji.
-    LifetimeContainsEmoji,
     /// Maybe there was a typo where a comma was forgotten before
     /// FRU syntax
     MaybeFruTypo,

compiler/rustc_lexer/src/lib.rs

@@ -95,7 +95,7 @@ pub enum TokenKind {
     Literal { kind: LiteralKind, suffix_start: u32 },
 
     /// "'a"
-    Lifetime { starts_with_number: bool, contains_emoji: bool },
+    Lifetime { starts_with_number: bool },
 
     // One-char tokens:
     /// ";"
@@ -632,13 +632,7 @@ impl Cursor<'_> {
             // If the first symbol is valid for identifier, it can be a lifetime.
             // Also check if it's a number for a better error reporting (so '0 will
             // be reported as invalid lifetime and not as unterminated char literal).
-            // We also have to account for potential `'🐱` emojis to avoid reporting
-            // it as an unterminated char literal.
-            is_id_start(self.first())
-                || self.first().is_digit(10)
-                // FIXME(#108019): `unic-emoji-char` seems to have data tables only up to Unicode
-                // 5.0, but Unicode is already newer than this.
-                || unic_emoji_char::is_emoji(self.first())
+            is_id_start(self.first()) || self.first().is_digit(10)
         };
 
         if !can_be_a_lifetime {
@@ -651,33 +645,16 @@ impl Cursor<'_> {
             return Literal { kind, suffix_start };
         }
 
-        // Either a lifetime or a character literal.
+        // Either a lifetime or a character literal with
+        // length greater than 1.
 
         let starts_with_number = self.first().is_digit(10);
-        let mut contains_emoji = false;
 
-        // FIXME(#108019): `unic-emoji-char` seems to have data tables only up to Unicode
-        // 5.0, but Unicode is already newer than this.
-        if unic_emoji_char::is_emoji(self.first()) {
-            contains_emoji = true;
-        } else {
-            // Skip the literal contents.
-            // First symbol can be a number (which isn't a valid identifier start),
-            // so skip it without any checks.
-            self.bump();
-        }
-        self.eat_while(|c| {
-            if is_id_continue(c) {
-                true
-            // FIXME(#108019): `unic-emoji-char` seems to have data tables only up to Unicode
-            // 5.0, but Unicode is already newer than this.
-            } else if unic_emoji_char::is_emoji(c) {
-                contains_emoji = true;
-                true
-            } else {
-                false
-            }
-        });
+        // Skip the literal contents.
+        // First symbol can be a number (which isn't a valid identifier start),
+        // so skip it without any checks.
+        self.bump();
+        self.eat_while(is_id_continue);
 
         // Check if after skipping literal contents we've met a closing
         // single quote (which means that user attempted to create a
@@ -687,7 +664,7 @@ impl Cursor<'_> {
             let kind = Char { terminated: true };
             Literal { kind, suffix_start: self.pos_within_token() }
         } else {
-            Lifetime { starts_with_number, contains_emoji }
+            Lifetime { starts_with_number }
         }
     }
 

compiler/rustc_lexer/src/tests.rs

@@ -235,7 +235,7 @@ fn lifetime() {
     check_lexing(
         "'abc",
         expect![[r#"
-            Token { kind: Lifetime { starts_with_number: false, contains_emoji: false }, len: 4 }
+            Token { kind: Lifetime { starts_with_number: false }, len: 4 }
         "#]],
     );
 }

compiler/rustc_parse/src/lexer/mod.rs

@@ -223,21 +223,16 @@ impl<'a> StringReader<'a> {
                     };
                     token::Literal(token::Lit { kind, symbol, suffix })
                 }
-                rustc_lexer::TokenKind::Lifetime { starts_with_number, contains_emoji } => {
+                rustc_lexer::TokenKind::Lifetime { starts_with_number } => {
                     // Include the leading `'` in the real identifier, for macro
                     // expansion purposes. See #12512 for the gory details of why
                     // this is necessary.
                     let lifetime_name = self.str_from(start);
                     if starts_with_number {
                         let span = self.mk_sp(start, self.pos);
-                        let mut diag = self.sess.struct_err("lifetimes or labels cannot start with a number");
+                        let mut diag = self.sess.struct_err("lifetimes cannot start with a number");
                         diag.set_span(span);
                         diag.stash(span, StashKey::LifetimeIsChar);
-                    } else if contains_emoji {
-                        let span = self.mk_sp(start, self.pos);
-                        let mut diag = self.sess.struct_err("lifetimes or labels cannot contain emojis");
-                        diag.set_span(span);
-                        diag.stash(span, StashKey::LifetimeContainsEmoji);
                     }
                     let ident = Symbol::intern(lifetime_name);
                     token::Lifetime(ident)

tests/ui/lexer/issue-108019-bad-emoji-recovery.rs

@@ -1,6 +1,6 @@
 struct S<'1> { s: &'1 usize }
-//~^ ERROR lifetimes or labels cannot start with a number
-//~| ERROR lifetimes or labels cannot start with a number
+//~^ ERROR lifetimes cannot start with a number
+//~| ERROR lifetimes cannot start with a number
 fn main() {
     // verify that the parse error doesn't stop type checking
     let x: usize = "";

tests/ui/lexer/issue-108019-bad-emoji-recovery.stderr

@@ -6,13 +6,13 @@ LL |     let x: usize = "";
    |            |
    |            expected due to this
 
-error: lifetimes or labels cannot start with a number
+error: lifetimes cannot start with a number
   --> $DIR/numeric-lifetime.rs:1:10
    |
 LL | struct S<'1> { s: &'1 usize }
    |          ^^
 
-error: lifetimes or labels cannot start with a number
+error: lifetimes cannot start with a number
   --> $DIR/numeric-lifetime.rs:1:20
    |
 LL | struct S<'1> { s: &'1 usize }