Rollup merge of #121120 - nnethercote:LitKind-Err-guar, r=fmease

Add `ErrorGuaranteed` to `ast::LitKind::Err`, `token::LitKind::Err`.

Similar to recent work doing the same for `ExprKind::Err` (#120586) and `TyKind::Err` (#121109).

r? `@oli-obk`

28 files changed, 170 insertions, 162 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 098e2606a3b..b74938621b3 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -1846,7 +1846,7 @@ pub enum LitKind {
     /// A boolean literal (`true`, `false`).
     Bool(bool),
     /// Placeholder for a literal that wasn't well-formed in some way.
-    Err,
+    Err(ErrorGuaranteed),
 }
 
 impl LitKind {
@@ -1893,7 +1893,7 @@ impl LitKind {
             | LitKind::Int(_, LitIntType::Unsuffixed)
             | LitKind::Float(_, LitFloatType::Unsuffixed)
             | LitKind::Bool(..)
-            | LitKind::Err => false,
+            | LitKind::Err(_) => false,
         }
     }
 }
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index d62462b1ae3..50fe37dcdb6 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -13,7 +13,7 @@ use rustc_macros::HashStable_Generic;
 use rustc_span::symbol::{kw, sym};
 #[allow(hidden_glob_reexports)]
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_span::{edition::Edition, Span, DUMMY_SP};
+use rustc_span::{edition::Edition, ErrorGuaranteed, Span, DUMMY_SP};
 use std::borrow::Cow;
 use std::fmt;
 
@@ -75,7 +75,7 @@ pub enum LitKind {
     ByteStrRaw(u8), // raw byte string delimited by `n` hash symbols
     CStr,
     CStrRaw(u8),
-    Err,
+    Err(ErrorGuaranteed),
 }
 
 /// A literal token.
@@ -144,7 +144,7 @@ impl fmt::Display for Lit {
             CStrRaw(n) => {
                 write!(f, "cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize))?
             }
-            Integer | Float | Bool | Err => write!(f, "{symbol}")?,
+            Integer | Float | Bool | Err(_) => write!(f, "{symbol}")?,
         }
 
         if let Some(suffix) = suffix {
@@ -159,7 +159,7 @@ impl LitKind {
     /// An English article for the literal token kind.
     pub fn article(self) -> &'static str {
         match self {
-            Integer | Err => "an",
+            Integer | Err(_) => "an",
             _ => "a",
         }
     }
@@ -174,12 +174,12 @@ impl LitKind {
             Str | StrRaw(..) => "string",
             ByteStr | ByteStrRaw(..) => "byte string",
             CStr | CStrRaw(..) => "C string",
-            Err => "error",
+            Err(_) => "error",
         }
     }
 
     pub(crate) fn may_have_suffix(self) -> bool {
-        matches!(self, Integer | Float | Err)
+        matches!(self, Integer | Float | Err(_))
     }
 }
 
diff --git a/compiler/rustc_ast/src/util/literal.rs b/compiler/rustc_ast/src/util/literal.rs
index aaeb1bb9bff..5ed2762b726 100644
--- a/compiler/rustc_ast/src/util/literal.rs
+++ b/compiler/rustc_ast/src/util/literal.rs
@@ -31,20 +31,21 @@ pub fn escape_byte_str_symbol(bytes: &[u8]) -> Symbol {
 
 #[derive(Debug)]
 pub enum LitError {
-    LexerError,
-    InvalidSuffix,
-    InvalidIntSuffix,
-    InvalidFloatSuffix,
-    NonDecimalFloat(u32),
-    IntTooLarge(u32),
+    InvalidSuffix(Symbol),
+    InvalidIntSuffix(Symbol),
+    InvalidFloatSuffix(Symbol),
+    NonDecimalFloat(u32), // u32 is the base
+    IntTooLarge(u32),     // u32 is the base
 }
 
 impl LitKind {
     /// Converts literal token into a semantic literal.
     pub fn from_token_lit(lit: token::Lit) -> Result<LitKind, LitError> {
         let token::Lit { kind, symbol, suffix } = lit;
-        if suffix.is_some() && !kind.may_have_suffix() {
-            return Err(LitError::InvalidSuffix);
+        if let Some(suffix) = suffix
+            && !kind.may_have_suffix()
+        {
+            return Err(LitError::InvalidSuffix(suffix));
         }
 
         // For byte/char/string literals, chars and escapes have already been
@@ -145,7 +146,7 @@ impl LitKind {
                 buf.push(0);
                 LitKind::CStr(buf.into(), StrStyle::Raw(n))
             }
-            token::Err => LitKind::Err,
+            token::Err(guar) => LitKind::Err(guar),
         })
     }
 }
@@ -202,7 +203,7 @@ impl fmt::Display for LitKind {
                 }
             }
             LitKind::Bool(b) => write!(f, "{}", if b { "true" } else { "false" })?,
-            LitKind::Err => {
+            LitKind::Err(_) => {
                 // This only shows up in places like `-Zunpretty=hir` output, so we
                 // don't bother to produce something useful.
                 write!(f, "<bad-literal>")?;
@@ -238,7 +239,7 @@ impl MetaItemLit {
             LitKind::Char(_) => token::Char,
             LitKind::Int(..) => token::Integer,
             LitKind::Float(..) => token::Float,
-            LitKind::Err => token::Err,
+            LitKind::Err(guar) => token::Err(guar),
         };
 
         token::Lit::new(kind, self.symbol, self.suffix)
@@ -272,12 +273,12 @@ fn filtered_float_lit(
         return Err(LitError::NonDecimalFloat(base));
     }
     Ok(match suffix {
-        Some(suf) => LitKind::Float(
+        Some(suffix) => LitKind::Float(
             symbol,
-            ast::LitFloatType::Suffixed(match suf {
+            ast::LitFloatType::Suffixed(match suffix {
                 sym::f32 => ast::FloatTy::F32,
                 sym::f64 => ast::FloatTy::F64,
-                _ => return Err(LitError::InvalidFloatSuffix),
+                _ => return Err(LitError::InvalidFloatSuffix(suffix)),
             }),
         ),
         None => LitKind::Float(symbol, ast::LitFloatType::Unsuffixed),
@@ -318,17 +319,13 @@ fn integer_lit(symbol: Symbol, suffix: Option<Symbol>) -> Result<LitKind, LitErr
             // `1f64` and `2f32` etc. are valid float literals, and
             // `fxxx` looks more like an invalid float literal than invalid integer literal.
             _ if suf.as_str().starts_with('f') => return filtered_float_lit(symbol, suffix, base),
-            _ => return Err(LitError::InvalidIntSuffix),
+            _ => return Err(LitError::InvalidIntSuffix(suf)),
         },
         _ => ast::LitIntType::Unsuffixed,
     };
 
     let s = &s[if base != 10 { 2 } else { 0 }..];
-    u128::from_str_radix(s, base).map(|i| LitKind::Int(i.into(), ty)).map_err(|_| {
-        // Small bases are lexed as if they were base 10, e.g, the string
-        // might be `0b10201`. This will cause the conversion above to fail,
-        // but these kinds of errors are already reported by the lexer.
-        let from_lexer = base < 10 && s.chars().any(|c| c.to_digit(10).is_some_and(|d| d >= base));
-        if from_lexer { LitError::LexerError } else { LitError::IntTooLarge(base) }
-    })
+    u128::from_str_radix(s, base)
+        .map(|i| LitKind::Int(i.into(), ty))
+        .map_err(|_| LitError::IntTooLarge(base))
 }
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 942aae3d536..aafa99b3aa6 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -124,8 +124,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let lit_kind = match LitKind::from_token_lit(*token_lit) {
                         Ok(lit_kind) => lit_kind,
                         Err(err) => {
-                            report_lit_error(&self.tcx.sess.parse_sess, err, *token_lit, e.span);
-                            LitKind::Err
+                            let guar = report_lit_error(
+                                &self.tcx.sess.parse_sess,
+                                err,
+                                *token_lit,
+                                e.span,
+                            );
+                            LitKind::Err(guar)
                         }
                     };
                     let lit = self.arena.alloc(respan(self.lower_span(e.span), lit_kind));
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 6b5fc014240..eab1383b635 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -966,10 +966,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 {
                     lit
                 } else {
+                    let guar = self.dcx().has_errors().unwrap();
                     MetaItemLit {
                         symbol: kw::Empty,
                         suffix: None,
-                        kind: LitKind::Err,
+                        kind: LitKind::Err(guar),
                         span: DUMMY_SP,
                     }
                 };
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index cda746894e8..2765b235f99 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -254,7 +254,7 @@ fn literal_to_string(lit: token::Lit) -> String {
         token::CStrRaw(n) => {
             format!("cr{delim}\"{symbol}\"{delim}", delim = "#".repeat(n as usize))
         }
-        token::Integer | token::Float | token::Bool | token::Err => symbol.to_string(),
+        token::Integer | token::Float | token::Bool | token::Err(_) => symbol.to_string(),
     };
 
     if let Some(suffix) = suffix {
diff --git a/compiler/rustc_builtin_macros/src/concat.rs b/compiler/rustc_builtin_macros/src/concat.rs
index dade29593af..795161e65d8 100644
--- a/compiler/rustc_builtin_macros/src/concat.rs
+++ b/compiler/rustc_builtin_macros/src/concat.rs
@@ -40,7 +40,7 @@ pub fn expand_concat(
                     cx.dcx().emit_err(errors::ConcatBytestr { span: e.span });
                     has_errors = true;
                 }
-                Ok(ast::LitKind::Err) => {
+                Ok(ast::LitKind::Err(_)) => {
                     has_errors = true;
                 }
                 Err(err) => {
diff --git a/compiler/rustc_builtin_macros/src/concat_bytes.rs b/compiler/rustc_builtin_macros/src/concat_bytes.rs
index a01bbeac824..3ef8cb7bffe 100644
--- a/compiler/rustc_builtin_macros/src/concat_bytes.rs
+++ b/compiler/rustc_builtin_macros/src/concat_bytes.rs
@@ -44,7 +44,7 @@ fn invalid_type_err(
         Ok(ast::LitKind::Bool(_)) => {
             dcx.emit_err(ConcatBytesInvalid { span, lit_kind: "boolean", sugg: None });
         }
-        Ok(ast::LitKind::Err) => {}
+        Ok(ast::LitKind::Err(_)) => {}
         Ok(ast::LitKind::Int(_, _)) if !is_nested => {
             let sugg =
                 snippet.map(|snippet| ConcatBytesInvalidSuggestion::IntLit { span: span, snippet });
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index cfeb31fc4c8..09ab26421d6 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -1266,7 +1266,7 @@ pub fn expr_to_spanned_string<'a>(
                 );
                 Some((err, true))
             }
-            Ok(ast::LitKind::Err) => None,
+            Ok(ast::LitKind::Err(_)) => None,
             Err(err) => {
                 report_lit_error(&cx.sess.parse_sess, err, token_lit, expr.span);
                 None
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 3a78bd94505..8f31b5801da 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -10,7 +10,7 @@ use rustc_ast::util::literal::escape_byte_str_symbol;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::{MultiSpan, PResult};
+use rustc_errors::{ErrorGuaranteed, MultiSpan, PResult};
 use rustc_parse::lexer::nfc_normalize;
 use rustc_parse::parse_stream_from_source_str;
 use rustc_session::parse::ParseSess;
@@ -63,7 +63,12 @@ impl FromInternal<token::LitKind> for LitKind {
             token::ByteStrRaw(n) => LitKind::ByteStrRaw(n),
             token::CStr => LitKind::CStr,
             token::CStrRaw(n) => LitKind::CStrRaw(n),
-            token::Err => LitKind::Err,
+            token::Err(_guar) => {
+                // This is the only place a `pm::bridge::LitKind::ErrWithGuar`
+                // is constructed. Note that an `ErrorGuaranteed` is available,
+                // as required. See the comment in `to_internal`.
+                LitKind::ErrWithGuar
+            }
             token::Bool => unreachable!(),
         }
     }
@@ -82,7 +87,16 @@ impl ToInternal<token::LitKind> for LitKind {
             LitKind::ByteStrRaw(n) => token::ByteStrRaw(n),
             LitKind::CStr => token::CStr,
             LitKind::CStrRaw(n) => token::CStrRaw(n),
-            LitKind::Err => token::Err,
+            LitKind::ErrWithGuar => {
+                // This is annoying but valid. `LitKind::ErrWithGuar` would
+                // have an `ErrorGuaranteed` except that type isn't available
+                // in that crate. So we have to fake one. And we don't want to
+                // use a delayed bug because there might be lots of these,
+                // which would be expensive.
+                #[allow(deprecated)]
+                let guar = ErrorGuaranteed::unchecked_error_guaranteed();
+                token::Err(guar)
+            }
         }
     }
 }
@@ -477,7 +491,7 @@ impl server::FreeFunctions for Rustc<'_, '_> {
                 | token::LitKind::ByteStrRaw(_)
                 | token::LitKind::CStr
                 | token::LitKind::CStrRaw(_)
-                | token::LitKind::Err => return Err(()),
+                | token::LitKind::Err(_) => return Err(()),
                 token::LitKind::Integer | token::LitKind::Float => {}
             }
 
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index 65b8505c090..3bce8a1dd45 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -1319,7 +1319,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 tcx.type_of(tcx.require_lang_item(hir::LangItem::CStr, Some(lit.span)))
                     .skip_binder(),
             ),
-            ast::LitKind::Err => Ty::new_misc_error(tcx),
+            ast::LitKind::Err(guar) => Ty::new_error(tcx, guar),
         }
     }
 
diff --git a/compiler/rustc_mir_build/src/build/expr/as_constant.rs b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
index 6636f75d998..7c3d2671d59 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_constant.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
@@ -164,11 +164,7 @@ fn lit_to_mir_constant<'tcx>(
             })?,
         (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
         (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
-        (ast::LitKind::Err, _) => {
-            return Err(LitToConstError::Reported(
-                tcx.dcx().delayed_bug("encountered LitKind::Err during mir build"),
-            ));
-        }
+        (ast::LitKind::Err(guar), _) => return Err(LitToConstError::Reported(*guar)),
         _ => return Err(LitToConstError::TypeError),
     };
 
diff --git a/compiler/rustc_mir_build/src/thir/constant.rs b/compiler/rustc_mir_build/src/thir/constant.rs
index 71aebd13003..d444de8b28e 100644
--- a/compiler/rustc_mir_build/src/thir/constant.rs
+++ b/compiler/rustc_mir_build/src/thir/constant.rs
@@ -71,11 +71,7 @@ pub(crate) fn lit_to_const<'tcx>(
             ty::ValTree::from_scalar_int(bits)
         }
         (ast::LitKind::Char(c), ty::Char) => ty::ValTree::from_scalar_int((*c).into()),
-        (ast::LitKind::Err, _) => {
-            return Err(LitToConstError::Reported(
-                tcx.dcx().delayed_bug("encountered LitKind::Err during mir build"),
-            ));
-        }
+        (ast::LitKind::Err(guar), _) => return Err(LitToConstError::Reported(*guar)),
         _ => return Err(LitToConstError::TypeError),
     };
 
diff --git a/compiler/rustc_mir_build/src/thir/cx/expr.rs b/compiler/rustc_mir_build/src/thir/cx/expr.rs
index 99952e1c178..62762168cf4 100644
--- a/compiler/rustc_mir_build/src/thir/cx/expr.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/expr.rs
@@ -897,12 +897,14 @@ impl<'tcx> Cx<'tcx> {
                 let hir_id = self.tcx.local_def_id_to_hir_id(def_id.expect_local());
                 let generics = self.tcx.generics_of(hir_id.owner);
                 let Some(&index) = generics.param_def_id_to_index.get(&def_id) else {
-                    self.tcx.dcx().has_errors().unwrap();
+                    let guar = self.tcx.dcx().has_errors().unwrap();
                     // We already errored about a late bound const
-                    return ExprKind::Literal {
-                        lit: &Spanned { span: DUMMY_SP, node: LitKind::Err },
-                        neg: false,
-                    };
+
+                    let lit = self
+                        .tcx
+                        .hir_arena
+                        .alloc(Spanned { span: DUMMY_SP, node: LitKind::Err(guar) });
+                    return ExprKind::Literal { lit, neg: false };
                 };
                 let name = self.tcx.hir().name(hir_id);
                 let param = ty::ParamConst::new(index, name);
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 31552452676..c768ea93b5f 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -16,7 +16,7 @@ use rustc_session::lint::builtin::{
 };
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::parse::ParseSess;
-use rustc_span::symbol::{sym, Symbol};
+use rustc_span::symbol::Symbol;
 use rustc_span::{edition::Edition, BytePos, Pos, Span};
 
 mod diagnostics;
@@ -478,26 +478,27 @@ impl<'sess, 'src> StringReader<'sess, 'src> {
                 }
             }
             rustc_lexer::LiteralKind::Int { base, empty_int } => {
+                let mut kind = token::Integer;
                 if empty_int {
                     let span = self.mk_sp(start, end);
-                    self.dcx().emit_err(errors::NoDigitsLiteral { span });
-                    (token::Integer, sym::integer(0))
-                } else {
-                    if matches!(base, Base::Binary | Base::Octal) {
-                        let base = base as u32;
-                        let s = self.str_from_to(start + BytePos(2), end);
-                        for (idx, c) in s.char_indices() {
-                            let span = self.mk_sp(
-                                start + BytePos::from_usize(2 + idx),
-                                start + BytePos::from_usize(2 + idx + c.len_utf8()),
-                            );
-                            if c != '_' && c.to_digit(base).is_none() {
+                    let guar = self.dcx().emit_err(errors::NoDigitsLiteral { span });
+                    kind = token::Err(guar);
+                } else if matches!(base, Base::Binary | Base::Octal) {
+                    let base = base as u32;
+                    let s = self.str_from_to(start + BytePos(2), end);
+                    for (idx, c) in s.char_indices() {
+                        let span = self.mk_sp(
+                            start + BytePos::from_usize(2 + idx),
+                            start + BytePos::from_usize(2 + idx + c.len_utf8()),
+                        );
+                        if c != '_' && c.to_digit(base).is_none() {
+                            let guar =
                                 self.dcx().emit_err(errors::InvalidDigitLiteral { span, base });
-                            }
+                            kind = token::Err(guar);
                         }
                     }
-                    (token::Integer, self.symbol_from_to(start, end))
                 }
+                (kind, self.symbol_from_to(start, end))
             }
             rustc_lexer::LiteralKind::Float { base, empty_exponent } => {
                 if empty_exponent {
@@ -691,7 +692,7 @@ impl<'sess, 'src> StringReader<'sess, 'src> {
 
     fn cook_common(
         &self,
-        kind: token::LitKind,
+        mut kind: token::LitKind,
         mode: Mode,
         start: BytePos,
         end: BytePos,
@@ -699,7 +700,6 @@ impl<'sess, 'src> StringReader<'sess, 'src> {
         postfix_len: u32,
         unescape: fn(&str, Mode, &mut dyn FnMut(Range<usize>, Result<(), EscapeError>)),
     ) -> (token::LitKind, Symbol) {
-        let mut has_fatal_err = false;
         let content_start = start + BytePos(prefix_len);
         let content_end = end - BytePos(postfix_len);
         let lit_content = self.str_from_to(content_start, content_end);
@@ -711,10 +711,8 @@ impl<'sess, 'src> StringReader<'sess, 'src> {
                 let lo = content_start + BytePos(start);
                 let hi = lo + BytePos(end - start);
                 let span = self.mk_sp(lo, hi);
-                if err.is_fatal() {
-                    has_fatal_err = true;
-                }
-                emit_unescape_error(
+                let is_fatal = err.is_fatal();
+                if let Some(guar) = emit_unescape_error(
                     self.dcx(),
                     lit_content,
                     span_with_quotes,
@@ -722,17 +720,21 @@ impl<'sess, 'src> StringReader<'sess, 'src> {
                     mode,
                     range,
                     err,
-                );
+                ) {
+                    assert!(is_fatal);
+                    kind = token::Err(guar);
+                }
             }
         });
 
         // We normally exclude the quotes for the symbol, but for errors we
         // include it because it results in clearer error messages.
-        if !has_fatal_err {
-            (kind, Symbol::intern(lit_content))
+        let sym = if !matches!(kind, token::Err(_)) {
+            Symbol::intern(lit_content)
         } else {
-            (token::Err, self.symbol_from_to(start, end))
-        }
+            self.symbol_from_to(start, end)
+        };
+        (kind, sym)
     }
 
     fn cook_unicode(
diff --git a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
index 3238f8e23bb..3ebad6a9fd7 100644
--- a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
+++ b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
@@ -3,7 +3,7 @@
 use std::iter::once;
 use std::ops::Range;
 
-use rustc_errors::{Applicability, DiagCtxt};
+use rustc_errors::{Applicability, DiagCtxt, ErrorGuaranteed};
 use rustc_lexer::unescape::{EscapeError, Mode};
 use rustc_span::{BytePos, Span};
 
@@ -21,7 +21,7 @@ pub(crate) fn emit_unescape_error(
     // range of the error inside `lit`
     range: Range<usize>,
     error: EscapeError,
-) {
+) -> Option<ErrorGuaranteed> {
     debug!(
         "emit_unescape_error: {:?}, {:?}, {:?}, {:?}, {:?}",
         lit, full_lit_span, mode, range, error
@@ -31,12 +31,12 @@ pub(crate) fn emit_unescape_error(
         let span = err_span.with_lo(err_span.hi() - BytePos(c.len_utf8() as u32));
         (c, span)
     };
-    match error {
+    Some(match error {
         EscapeError::LoneSurrogateUnicodeEscape => {
-            dcx.emit_err(UnescapeError::InvalidUnicodeEscape { span: err_span, surrogate: true });
+            dcx.emit_err(UnescapeError::InvalidUnicodeEscape { span: err_span, surrogate: true })
         }
         EscapeError::OutOfRangeUnicodeEscape => {
-            dcx.emit_err(UnescapeError::InvalidUnicodeEscape { span: err_span, surrogate: false });
+            dcx.emit_err(UnescapeError::InvalidUnicodeEscape { span: err_span, surrogate: false })
         }
         EscapeError::MoreThanOneChar => {
             use unicode_normalization::{char::is_combining_mark, UnicodeNormalization};
@@ -106,7 +106,7 @@ pub(crate) fn emit_unescape_error(
                 span: full_lit_span,
                 note,
                 suggestion: sugg,
-            });
+            })
         }
         EscapeError::EscapeOnlyChar => {
             let (c, char_span) = last_char();
@@ -116,15 +116,15 @@ pub(crate) fn emit_unescape_error(
                 escaped_sugg: c.escape_default().to_string(),
                 escaped_msg: escaped_char(c),
                 byte: mode == Mode::Byte,
-            });
+            })
         }
         EscapeError::BareCarriageReturn => {
             let double_quotes = mode.in_double_quotes();
-            dcx.emit_err(UnescapeError::BareCr { span: err_span, double_quotes });
+            dcx.emit_err(UnescapeError::BareCr { span: err_span, double_quotes })
         }
         EscapeError::BareCarriageReturnInRawString => {
             assert!(mode.in_double_quotes());
-            dcx.emit_err(UnescapeError::BareCrRawString(err_span));
+            dcx.emit_err(UnescapeError::BareCrRawString(err_span))
         }
         EscapeError::InvalidEscape => {
             let (c, span) = last_char();
@@ -161,16 +161,14 @@ pub(crate) fn emit_unescape_error(
                      <https://doc.rust-lang.org/reference/tokens.html#literals>",
                 );
             }
-            diag.emit();
-        }
-        EscapeError::TooShortHexEscape => {
-            dcx.emit_err(UnescapeError::TooShortHexEscape(err_span));
+            diag.emit()
         }
+        EscapeError::TooShortHexEscape => dcx.emit_err(UnescapeError::TooShortHexEscape(err_span)),
         EscapeError::InvalidCharInHexEscape | EscapeError::InvalidCharInUnicodeEscape => {
             let (c, span) = last_char();
             let is_hex = error == EscapeError::InvalidCharInHexEscape;
             let ch = escaped_char(c);
-            dcx.emit_err(UnescapeError::InvalidCharInEscape { span, is_hex, ch });
+            dcx.emit_err(UnescapeError::InvalidCharInEscape { span, is_hex, ch })
         }
         EscapeError::NonAsciiCharInByte => {
             let (c, span) = last_char();
@@ -213,23 +211,23 @@ pub(crate) fn emit_unescape_error(
                     Applicability::MaybeIncorrect,
                 );
             }
-            err.emit();
+            err.emit()
         }
         EscapeError::OutOfRangeHexEscape => {
-            dcx.emit_err(UnescapeError::OutOfRangeHexEscape(err_span));
+            dcx.emit_err(UnescapeError::OutOfRangeHexEscape(err_span))
         }
         EscapeError::LeadingUnderscoreUnicodeEscape => {
             let (c, span) = last_char();
             dcx.emit_err(UnescapeError::LeadingUnderscoreUnicodeEscape {
                 span,
                 ch: escaped_char(c),
-            });
+            })
         }
         EscapeError::OverlongUnicodeEscape => {
-            dcx.emit_err(UnescapeError::OverlongUnicodeEscape(err_span));
+            dcx.emit_err(UnescapeError::OverlongUnicodeEscape(err_span))
         }
         EscapeError::UnclosedUnicodeEscape => {
-            dcx.emit_err(UnescapeError::UnclosedUnicodeEscape(err_span, err_span.shrink_to_hi()));
+            dcx.emit_err(UnescapeError::UnclosedUnicodeEscape(err_span, err_span.shrink_to_hi()))
         }
         EscapeError::NoBraceInUnicodeEscape => {
             let mut suggestion = "\\u{".to_owned();
@@ -248,23 +246,17 @@ pub(crate) fn emit_unescape_error(
             } else {
                 (Some(err_span), NoBraceUnicodeSub::Help)
             };
-            dcx.emit_err(UnescapeError::NoBraceInUnicodeEscape { span: err_span, label, sub });
+            dcx.emit_err(UnescapeError::NoBraceInUnicodeEscape { span: err_span, label, sub })
         }
         EscapeError::UnicodeEscapeInByte => {
-            dcx.emit_err(UnescapeError::UnicodeEscapeInByte(err_span));
+            dcx.emit_err(UnescapeError::UnicodeEscapeInByte(err_span))
         }
         EscapeError::EmptyUnicodeEscape => {
-            dcx.emit_err(UnescapeError::EmptyUnicodeEscape(err_span));
-        }
-        EscapeError::ZeroChars => {
-            dcx.emit_err(UnescapeError::ZeroChars(err_span));
-        }
-        EscapeError::LoneSlash => {
-            dcx.emit_err(UnescapeError::LoneSlash(err_span));
-        }
-        EscapeError::NulInCStr => {
-            dcx.emit_err(UnescapeError::NulInCStr { span: err_span });
+            dcx.emit_err(UnescapeError::EmptyUnicodeEscape(err_span))
         }
+        EscapeError::ZeroChars => dcx.emit_err(UnescapeError::ZeroChars(err_span)),
+        EscapeError::LoneSlash => dcx.emit_err(UnescapeError::LoneSlash(err_span)),
+        EscapeError::NulInCStr => dcx.emit_err(UnescapeError::NulInCStr { span: err_span }),
         EscapeError::UnskippedWhitespaceWarning => {
             let (c, char_span) = last_char();
             dcx.emit_warn(UnescapeError::UnskippedWhitespace {
@@ -272,11 +264,13 @@ pub(crate) fn emit_unescape_error(
                 ch: escaped_char(c),
                 char_span,
             });
+            return None;
         }
         EscapeError::MultipleSkippedLinesWarning => {
             dcx.emit_warn(UnescapeError::MultipleSkippedLinesWarning(err_span));
+            return None;
         }
-    }
+    })
 }
 
 /// Pushes a character to a message string for error reporting
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 1a57474bac2..2424b6c130d 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -2140,12 +2140,12 @@ impl<'a> Parser<'a> {
                     Err(err) => {
                         let span = token.uninterpolated_span();
                         self.bump();
-                        report_lit_error(self.sess, err, lit, span);
+                        let guar = report_lit_error(self.sess, err, lit, span);
                         // Pack possible quotes and prefixes from the original literal into
                         // the error literal's symbol so they can be pretty-printed faithfully.
                         let suffixless_lit = token::Lit::new(lit.kind, lit.symbol, None);
                         let symbol = Symbol::intern(&suffixless_lit.to_string());
-                        let lit = token::Lit::new(token::Err, symbol, lit.suffix);
+                        let lit = token::Lit::new(token::Err(guar), symbol, lit.suffix);
                         Some(
                             MetaItemLit::from_token_lit(lit, span)
                                 .unwrap_or_else(|_| unreachable!()),
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 623407eb380..dea2b9e6ca7 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -1459,7 +1459,7 @@ impl<'a> Parser<'a> {
         match self.parse_str_lit() {
             Ok(str_lit) => Some(str_lit),
             Err(Some(lit)) => match lit.kind {
-                ast::LitKind::Err => None,
+                ast::LitKind::Err(_) => None,
                 _ => {
                     self.dcx().emit_err(NonStringAbiLiteral { span: lit.span });
                     None
diff --git a/compiler/rustc_parse/src/validate_attr.rs b/compiler/rustc_parse/src/validate_attr.rs
index 2fafbd6d97b..b0982029657 100644
--- a/compiler/rustc_parse/src/validate_attr.rs
+++ b/compiler/rustc_parse/src/validate_attr.rs
@@ -70,11 +70,11 @@ pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, Meta
                             }
                         }
                         Err(err) => {
-                            report_lit_error(sess, err, token_lit, expr.span);
+                            let guar = report_lit_error(sess, err, token_lit, expr.span);
                             let lit = ast::MetaItemLit {
                                 symbol: token_lit.symbol,
                                 suffix: token_lit.suffix,
-                                kind: ast::LitKind::Err,
+                                kind: ast::LitKind::Err(guar),
                                 span: expr.span,
                             };
                             MetaItemKind::NameValue(lit)
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index c36cec6f353..82846e3b4e8 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -3,7 +3,8 @@ use std::num::NonZeroU32;
 use rustc_ast::token;
 use rustc_ast::util::literal::LitError;
 use rustc_errors::{
-    codes::*, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, IntoDiagnostic, Level, MultiSpan,
+    codes::*, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, IntoDiagnostic,
+    Level, MultiSpan,
 };
 use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
@@ -344,7 +345,12 @@ pub(crate) struct BinaryFloatLiteralNotSupported {
     pub span: Span,
 }
 
-pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span: Span) {
+pub fn report_lit_error(
+    sess: &ParseSess,
+    err: LitError,
+    lit: token::Lit,
+    span: Span,
+) -> ErrorGuaranteed {
     // Checks if `s` looks like i32 or u1234 etc.
     fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
         s.len() > 1 && s.starts_with(first_chars) && s[1..].chars().all(|c| c.is_ascii_digit())
@@ -372,47 +378,37 @@ pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span:
         valid.then(|| format!("0{}{}", base_char.to_ascii_lowercase(), &suffix[1..]))
     }
 
-    let token::Lit { kind, symbol, suffix, .. } = lit;
     let dcx = &sess.dcx;
     match err {
-        // `LexerError` is an error, but it was already reported
-        // by lexer, so here we don't report it the second time.
-        LitError::LexerError => {}
-        LitError::InvalidSuffix => {
-            if let Some(suffix) = suffix {
-                dcx.emit_err(InvalidLiteralSuffix { span, kind: kind.descr(), suffix });
-            }
+        LitError::InvalidSuffix(suffix) => {
+            dcx.emit_err(InvalidLiteralSuffix { span, kind: lit.kind.descr(), suffix })
         }
-        LitError::InvalidIntSuffix => {
-            let suf = suffix.expect("suffix error with no suffix");
-            let suf = suf.as_str();
+        LitError::InvalidIntSuffix(suffix) => {
+            let suf = suffix.as_str();
             if looks_like_width_suffix(&['i', 'u'], suf) {
                 // If it looks like a width, try to be helpful.
-                dcx.emit_err(InvalidIntLiteralWidth { span, width: suf[1..].into() });
-            } else if let Some(fixed) = fix_base_capitalisation(symbol.as_str(), suf) {
-                dcx.emit_err(InvalidNumLiteralBasePrefix { span, fixed });
+                dcx.emit_err(InvalidIntLiteralWidth { span, width: suf[1..].into() })
+            } else if let Some(fixed) = fix_base_capitalisation(lit.symbol.as_str(), suf) {
+                dcx.emit_err(InvalidNumLiteralBasePrefix { span, fixed })
             } else {
-                dcx.emit_err(InvalidNumLiteralSuffix { span, suffix: suf.to_string() });
+                dcx.emit_err(InvalidNumLiteralSuffix { span, suffix: suf.to_string() })
             }
         }
-        LitError::InvalidFloatSuffix => {
-            let suf = suffix.expect("suffix error with no suffix");
-            let suf = suf.as_str();
+        LitError::InvalidFloatSuffix(suffix) => {
+            let suf = suffix.as_str();
             if looks_like_width_suffix(&['f'], suf) {
                 // If it looks like a width, try to be helpful.
-                dcx.emit_err(InvalidFloatLiteralWidth { span, width: suf[1..].to_string() });
+                dcx.emit_err(InvalidFloatLiteralWidth { span, width: suf[1..].to_string() })
             } else {
-                dcx.emit_err(InvalidFloatLiteralSuffix { span, suffix: suf.to_string() });
+                dcx.emit_err(InvalidFloatLiteralSuffix { span, suffix: suf.to_string() })
             }
         }
-        LitError::NonDecimalFloat(base) => {
-            match base {
-                16 => dcx.emit_err(HexadecimalFloatLiteralNotSupported { span }),
-                8 => dcx.emit_err(OctalFloatLiteralNotSupported { span }),
-                2 => dcx.emit_err(BinaryFloatLiteralNotSupported { span }),
-                _ => unreachable!(),
-            };
-        }
+        LitError::NonDecimalFloat(base) => match base {
+            16 => dcx.emit_err(HexadecimalFloatLiteralNotSupported { span }),
+            8 => dcx.emit_err(OctalFloatLiteralNotSupported { span }),
+            2 => dcx.emit_err(BinaryFloatLiteralNotSupported { span }),
+            _ => unreachable!(),
+        },
         LitError::IntTooLarge(base) => {
             let max = u128::MAX;
             let limit = match base {
@@ -421,7 +417,7 @@ pub fn report_lit_error(sess: &ParseSess, err: LitError, lit: token::Lit, span:
                 16 => format!("{max:#x}"),
                 _ => format!("{max}"),
             };
-            dcx.emit_err(IntLiteralTooLarge { span, limit });
+            dcx.emit_err(IntLiteralTooLarge { span, limit })
         }
     }
 }
diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 55e24b6491c..9b337f23867 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -337,7 +337,11 @@ pub enum LitKind {
     ByteStrRaw(u8),
     CStr,
     CStrRaw(u8),
-    Err,
+    // This should have an `ErrorGuaranteed`, except that type isn't available
+    // in this crate. (Imagine it is there.) Hence the `WithGuar` suffix. Must
+    // only be constructed in `LitKind::from_internal`, where an
+    // `ErrorGuaranteed` is available.
+    ErrWithGuar,
 }
 
 rpc_encode_decode!(
@@ -352,7 +356,7 @@ rpc_encode_decode!(
         ByteStrRaw(n),
         CStr,
         CStrRaw(n),
-        Err,
+        ErrWithGuar,
     }
 );
 
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index 90b76cbc26e..7c492941713 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -1451,7 +1451,7 @@ impl Literal {
                 f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
             }
 
-            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::Err => {
+            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
                 f(&[symbol, suffix])
             }
         })
diff --git a/src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs b/src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs
index 6595658b769..b8f7d966820 100644
--- a/src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs
+++ b/src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs
@@ -295,7 +295,8 @@ impl<'a> NormalizedPat<'a> {
                     LitKind::Char(val) => Self::LitInt(val.into()),
                     LitKind::Int(val, _) => Self::LitInt(val.get()),
                     LitKind::Bool(val) => Self::LitBool(val),
-                    LitKind::Float(..) | LitKind::Err => Self::Wild,
+                    LitKind::Float(..) => Self::Wild,
+                    LitKind::Err(guar) => Self::Err(guar),
                 },
                 _ => Self::Wild,
             },
diff --git a/src/tools/clippy/clippy_lints/src/redundant_type_annotations.rs b/src/tools/clippy/clippy_lints/src/redundant_type_annotations.rs
index c8352c05265..079e6500e3c 100644
--- a/src/tools/clippy/clippy_lints/src/redundant_type_annotations.rs
+++ b/src/tools/clippy/clippy_lints/src/redundant_type_annotations.rs
@@ -200,7 +200,7 @@ impl LateLintPass<'_> for RedundantTypeAnnotations {
                                 span_lint(cx, REDUNDANT_TYPE_ANNOTATIONS, local.span, "redundant type annotation");
                             }
                         },
-                        LitKind::Err => (),
+                        LitKind::Err(_) => (),
                         LitKind::ByteStr(..) => {
                             // We only lint if the type annotation is an array type (e.g. &[u8; 4]).
                             // If instead it is a slice (e.g. &[u8]) it may not be redundant, so we
diff --git a/src/tools/clippy/clippy_lints/src/utils/author.rs b/src/tools/clippy/clippy_lints/src/utils/author.rs
index 29c67341a46..a0a6382046d 100644
--- a/src/tools/clippy/clippy_lints/src/utils/author.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/author.rs
@@ -279,7 +279,7 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
         match lit.value.node {
             LitKind::Bool(val) => kind!("Bool({val:?})"),
             LitKind::Char(c) => kind!("Char({c:?})"),
-            LitKind::Err => kind!("Err"),
+            LitKind::Err(_) => kind!("Err"),
             LitKind::Byte(b) => kind!("Byte({b})"),
             LitKind::Int(i, suffix) => {
                 let int_ty = match suffix {
diff --git a/src/tools/clippy/clippy_utils/src/consts.rs b/src/tools/clippy/clippy_utils/src/consts.rs
index 61b38391d9e..79c691992a8 100644
--- a/src/tools/clippy/clippy_utils/src/consts.rs
+++ b/src/tools/clippy/clippy_utils/src/consts.rs
@@ -286,7 +286,7 @@ pub fn lit_to_mir_constant<'tcx>(lit: &LitKind, ty: Option<Ty<'tcx>>) -> Constan
             _ => bug!(),
         },
         LitKind::Bool(b) => Constant::Bool(b),
-        LitKind::Err => Constant::Err,
+        LitKind::Err(_) => Constant::Err,
     }
 }
 
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/rust_analyzer_span.rs b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/rust_analyzer_span.rs
index c7c7bea9941..8a9d52a37a2 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/rust_analyzer_span.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/rust_analyzer_span.rs
@@ -72,7 +72,7 @@ impl server::FreeFunctions for RaSpanServer {
     ) -> Result<bridge::Literal<Self::Span, Self::Symbol>, ()> {
         // FIXME: keep track of LitKind and Suffix
         Ok(bridge::Literal {
-            kind: bridge::LitKind::Err,
+            kind: bridge::LitKind::Integer, // dummy
             symbol: Symbol::intern(self.interner, s),
             suffix: None,
             span: self.call_site,
@@ -202,7 +202,7 @@ impl server::TokenStream for RaSpanServer {
                 tt::TokenTree::Leaf(tt::Leaf::Literal(lit)) => {
                     bridge::TokenTree::Literal(bridge::Literal {
                         // FIXME: handle literal kinds
-                        kind: bridge::LitKind::Err,
+                        kind: bridge::LitKind::Integer, // dummy
                         symbol: Symbol::intern(self.interner, &lit.text),
                         // FIXME: handle suffixes
                         suffix: None,
diff --git a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/token_id.rs b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/token_id.rs
index edbdc67b482..15a9e0deae4 100644
--- a/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/token_id.rs
+++ b/src/tools/rust-analyzer/crates/proc-macro-srv/src/server/token_id.rs
@@ -64,7 +64,7 @@ impl server::FreeFunctions for TokenIdServer {
     ) -> Result<bridge::Literal<Self::Span, Self::Symbol>, ()> {
         // FIXME: keep track of LitKind and Suffix
         Ok(bridge::Literal {
-            kind: bridge::LitKind::Err,
+            kind: bridge::LitKind::Integer, // dummy
             symbol: Symbol::intern(self.interner, s),
             suffix: None,
             span: self.call_site,
@@ -187,7 +187,7 @@ impl server::TokenStream for TokenIdServer {
                 tt::TokenTree::Leaf(tt::Leaf::Literal(lit)) => {
                     bridge::TokenTree::Literal(bridge::Literal {
                         // FIXME: handle literal kinds
-                        kind: bridge::LitKind::Err,
+                        kind: bridge::LitKind::Integer, // dummy
                         symbol: Symbol::intern(self.interner, &lit.text),
                         // FIXME: handle suffixes
                         suffix: None,