Support #[fatal(..)]

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -331,7 +331,7 @@ impl<'a> AstValidator<'a> {
         let max_num_args: usize = u16::MAX.into();
         if fn_decl.inputs.len() > max_num_args {
             let Param { span, .. } = fn_decl.inputs[0];
-            self.session.emit_err(FnParamTooMany { span, max_num_args });
+            self.session.emit_fatal(FnParamTooMany { span, max_num_args });
         }
     }
 

compiler/rustc_ast_passes/src/errors.rs

@@ -106,7 +106,7 @@ pub struct ForbiddenNonLifetimeParam {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(ast_passes::fn_param_too_many)]
+#[fatal(ast_passes::fn_param_too_many)]
 pub struct FnParamTooMany {
     #[primary_span]
     pub span: Span,

compiler/rustc_session/src/parse.rs

@@ -360,6 +360,17 @@ impl ParseSess {
         self.create_warning(warning).emit()
     }
 
+    pub fn create_fatal<'a>(
+        &'a self,
+        fatal: impl SessionDiagnostic<'a, !>,
+    ) -> DiagnosticBuilder<'a, !> {
+        fatal.into_diagnostic(self)
+    }
+
+    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) -> ! {
+        self.create_fatal(fatal).emit()
+    }
+
     #[rustc_lint_diagnostics]
     pub fn struct_err(
         &self,
@@ -373,6 +384,11 @@ impl ParseSess {
         self.span_diagnostic.struct_warn(msg)
     }
 
+    #[rustc_lint_diagnostics]
+    pub fn struct_fatal(&self, msg: impl Into<DiagnosticMessage>) -> DiagnosticBuilder<'_, !> {
+        self.span_diagnostic.struct_fatal(msg)
+    }
+
     #[rustc_lint_diagnostics]
     pub fn struct_diagnostic<G: EmissionGuarantee>(
         &self,

compiler/rustc_session/src/session.rs

@@ -482,6 +482,15 @@ impl Session {
     pub fn emit_warning<'a>(&'a self, warning: impl SessionDiagnostic<'a, ()>) {
         self.parse_sess.emit_warning(warning)
     }
+    pub fn create_fatal<'a>(
+        &'a self,
+        fatal: impl SessionDiagnostic<'a, !>,
+    ) -> DiagnosticBuilder<'a, !> {
+        self.parse_sess.create_fatal(fatal)
+    }
+    pub fn emit_fatal<'a>(&'a self, fatal: impl SessionDiagnostic<'a, !>) {
+        self.parse_sess.emit_fatal(fatal)
+    }
     #[inline]
     pub fn err_count(&self) -> usize {
         self.diagnostic().err_count()