Rollup merge of #121427 - nnethercote:fix-Rocket, r=oli-obk

Fix panic when compiling `Rocket`.

This panic was reported [here](https://github.com/rust-lang/rust/pull/120576#issuecomment-1957515484).

r? ``@oli-obk``

compiler/rustc_expand/src/proc_macro_server.rs

@@ -510,7 +510,7 @@ fn literal_from_str(&mut self, s: &str) -> Result<Literal<Self::Span, Self::Symb
 
     fn emit_diagnostic(&mut self, diagnostic: Diagnostic<Self::Span>) {
         let message = rustc_errors::DiagnosticMessage::from(diagnostic.message);
-        let mut diag: DiagnosticBuilder<'_, rustc_errors::ErrorGuaranteed> =
+        let mut diag: DiagnosticBuilder<'_, ()> =
             DiagnosticBuilder::new(&self.sess().dcx, diagnostic.level.to_internal(), message);
         diag.span(MultiSpan::from_spans(diagnostic.spans));
         for child in diagnostic.children {

compiler/rustc_mir_build/src/errors.rs

@@ -461,8 +461,10 @@ pub(crate) struct NonExhaustivePatternsTypeNotEmpty<'p, 'tcx, 'm> {
     pub ty: Ty<'tcx>,
 }
 
-impl<'a> IntoDiagnostic<'a> for NonExhaustivePatternsTypeNotEmpty<'_, '_, '_> {
-    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'_> {
+impl<'a, G: EmissionGuarantee> IntoDiagnostic<'a, G>
+    for NonExhaustivePatternsTypeNotEmpty<'_, '_, '_>
+{
+    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'_, G> {
         let mut diag = DiagnosticBuilder::new(
             dcx,
             level,

compiler/rustc_parse/src/errors.rs

@@ -1073,9 +1073,9 @@ pub(crate) struct ExpectedIdentifier {
     pub help_cannot_start_number: Option<HelpIdentifierStartsWithNumber>,
 }
 
-impl<'a> IntoDiagnostic<'a> for ExpectedIdentifier {
+impl<'a, G: EmissionGuarantee> IntoDiagnostic<'a, G> for ExpectedIdentifier {
     #[track_caller]
-    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a> {
+    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a, G> {
         let token_descr = TokenDescription::from_token(&self.token);
 
         let mut diag = DiagnosticBuilder::new(
@@ -1133,9 +1133,9 @@ pub(crate) struct ExpectedSemi {
     pub sugg: ExpectedSemiSugg,
 }
 
-impl<'a> IntoDiagnostic<'a> for ExpectedSemi {
+impl<'a, G: EmissionGuarantee> IntoDiagnostic<'a, G> for ExpectedSemi {
     #[track_caller]
-    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a> {
+    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a, G> {
         let token_descr = TokenDescription::from_token(&self.token);
 
         let mut diag = DiagnosticBuilder::new(

compiler/rustc_session/src/errors.rs

@@ -3,8 +3,8 @@
 use rustc_ast::token;
 use rustc_ast::util::literal::LitError;
 use rustc_errors::{
-    codes::*, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, IntoDiagnostic,
-    Level, MultiSpan,
+    codes::*, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, ErrorGuaranteed,
+    IntoDiagnostic, Level, MultiSpan,
 };
 use rustc_macros::Diagnostic;
 use rustc_span::{Span, Symbol};
@@ -17,9 +17,9 @@ pub struct FeatureGateError {
     pub explain: DiagnosticMessage,
 }
 
-impl<'a> IntoDiagnostic<'a> for FeatureGateError {
+impl<'a, G: EmissionGuarantee> IntoDiagnostic<'a, G> for FeatureGateError {
     #[track_caller]
-    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a> {
+    fn into_diagnostic(self, dcx: &'a DiagCtxt, level: Level) -> DiagnosticBuilder<'a, G> {
         DiagnosticBuilder::new(dcx, level, self.explain).with_span(self.span).with_code(E0658)
     }
 }