4 files changed, 113 insertions, 18 deletions
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index dfd4f38cf03..797d4830c2f 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -8,8 +8,9 @@ use rustc_ast::{Path, Visibility};
 use rustc_errors::codes::*;
 use rustc_errors::{
     Applicability, Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level, Subdiagnostic,
+    SuggestionStyle,
 };
-use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::edition::{Edition, LATEST_STABLE_EDITION};
 use rustc_span::{Ident, Span, Symbol};
@@ -2228,11 +2229,10 @@ pub(crate) struct KeywordLifetime {
 }
 
 #[derive(Diagnostic)]
-#[diag(parse_invalid_label)]
-pub(crate) struct InvalidLabel {
+#[diag(parse_keyword_label)]
+pub(crate) struct KeywordLabel {
     #[primary_span]
     pub span: Span,
-    pub name: Symbol,
 }
 
 #[derive(Diagnostic)]
@@ -3602,3 +3602,76 @@ pub(crate) struct ExpectedRegisterClassOrExplicitRegister {
     #[primary_span]
     pub(crate) span: Span,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(parse_hidden_unicode_codepoints)]
+#[note]
+pub(crate) struct HiddenUnicodeCodepointsDiag {
+    pub label: String,
+    pub count: usize,
+    #[label]
+    pub span_label: Span,
+    #[subdiagnostic]
+    pub labels: Option<HiddenUnicodeCodepointsDiagLabels>,
+    #[subdiagnostic]
+    pub sub: HiddenUnicodeCodepointsDiagSub,
+}
+
+pub(crate) struct HiddenUnicodeCodepointsDiagLabels {
+    pub spans: Vec<(char, Span)>,
+}
+
+impl Subdiagnostic for HiddenUnicodeCodepointsDiagLabels {
+    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
+        for (c, span) in self.spans {
+            diag.span_label(span, format!("{c:?}"));
+        }
+    }
+}
+
+pub(crate) enum HiddenUnicodeCodepointsDiagSub {
+    Escape { spans: Vec<(char, Span)> },
+    NoEscape { spans: Vec<(char, Span)> },
+}
+
+// Used because of multiple multipart_suggestion and note
+impl Subdiagnostic for HiddenUnicodeCodepointsDiagSub {
+    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
+        match self {
+            HiddenUnicodeCodepointsDiagSub::Escape { spans } => {
+                diag.multipart_suggestion_with_style(
+                    fluent::parse_suggestion_remove,
+                    spans.iter().map(|(_, span)| (*span, "".to_string())).collect(),
+                    Applicability::MachineApplicable,
+                    SuggestionStyle::HideCodeAlways,
+                );
+                diag.multipart_suggestion(
+                    fluent::parse_suggestion_escape,
+                    spans
+                        .into_iter()
+                        .map(|(c, span)| {
+                            let c = format!("{c:?}");
+                            (span, c[1..c.len() - 1].to_string())
+                        })
+                        .collect(),
+                    Applicability::MachineApplicable,
+                );
+            }
+            HiddenUnicodeCodepointsDiagSub::NoEscape { spans } => {
+                // FIXME: in other suggestions we've reversed the inner spans of doc comments. We
+                // should do the same here to provide the same good suggestions as we do for
+                // literals above.
+                diag.arg(
+                    "escaped",
+                    spans
+                        .into_iter()
+                        .map(|(c, _)| format!("{c:?}"))
+                        .collect::<Vec<String>>()
+                        .join(", "),
+                );
+                diag.note(fluent::parse_suggestion_remove);
+                diag.note(fluent::parse_no_suggestion_note_escape);
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 7c7e7e50b27..9792240a548 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -543,21 +543,21 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
             })
             .collect();
 
+        let label = label.to_string();
         let count = spans.len();
-        let labels = point_at_inner_spans.then_some(spans.clone());
+        let labels = point_at_inner_spans
+            .then_some(errors::HiddenUnicodeCodepointsDiagLabels { spans: spans.clone() });
+        let sub = if point_at_inner_spans && !spans.is_empty() {
+            errors::HiddenUnicodeCodepointsDiagSub::Escape { spans }
+        } else {
+            errors::HiddenUnicodeCodepointsDiagSub::NoEscape { spans }
+        };
 
         self.psess.buffer_lint(
             TEXT_DIRECTION_CODEPOINT_IN_LITERAL,
             span,
             ast::CRATE_NODE_ID,
-            BuiltinLintDiag::HiddenUnicodeCodepoints {
-                label: label.to_string(),
-                count,
-                span_label: span,
-                labels,
-                escape: point_at_inner_spans && !spans.is_empty(),
-                spans,
-            },
+            errors::HiddenUnicodeCodepointsDiag { label, count, span_label: span, labels, sub },
         );
     }
 
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 6aa6fc2c790..1499808966c 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -3094,7 +3094,7 @@ impl<'a> Parser<'a> {
         if let Some((ident, is_raw)) = self.token.lifetime() {
             // Disallow `'fn`, but with a better error message than `expect_lifetime`.
             if matches!(is_raw, IdentIsRaw::No) && ident.without_first_quote().is_reserved() {
-                self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
+                self.dcx().emit_err(errors::KeywordLabel { span: ident.span });
             }
 
             self.bump();
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index 899a43955ab..6168647183f 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -137,14 +137,37 @@ impl<'a> Parser<'a> {
     /// The difference from `parse_ty` is that this version allows `...`
     /// (`CVarArgs`) at the top level of the type.
     pub(super) fn parse_ty_for_param(&mut self) -> PResult<'a, Box<Ty>> {
-        self.parse_ty_common(
+        let ty = self.parse_ty_common(
             AllowPlus::Yes,
             AllowCVariadic::Yes,
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::Yes,
-        )
+        )?;
+
+        // Recover a trailing `= EXPR` if present.
+        if self.may_recover()
+            && self.check_noexpect(&token::Eq)
+            && self.look_ahead(1, |tok| tok.can_begin_expr())
+        {
+            let snapshot = self.create_snapshot_for_diagnostic();
+            self.bump();
+            let eq_span = self.prev_token.span;
+            match self.parse_expr() {
+                Ok(e) => {
+                    self.dcx()
+                        .struct_span_err(eq_span.to(e.span), "parameter defaults are not supported")
+                        .emit();
+                }
+                Err(diag) => {
+                    diag.cancel();
+                    self.restore_snapshot(snapshot);
+                }
+            }
+        }
+
+        Ok(ty)
     }
 
     /// Parses a type in restricted contexts where `+` is not permitted.
@@ -1479,8 +1502,7 @@ impl<'a> Parser<'a> {
     pub(super) fn expect_lifetime(&mut self) -> Lifetime {
         if let Some((ident, is_raw)) = self.token.lifetime() {
             if matches!(is_raw, IdentIsRaw::No)
-                && ident.without_first_quote().is_reserved()
-                && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&ident.name)
+                && ident.without_first_quote().is_reserved_lifetime()
             {
                 self.dcx().emit_err(errors::KeywordLifetime { span: ident.span });
             }