From 7fe4f0701c34fd107101a6bdb2d62e0935d798a4 Mon Sep 17 00:00:00 2001
From: Tshepang Mbambo <tshepang@gmail.com>
Date: Sat, 4 Mar 2023 07:54:29 +0200
Subject: [PATCH] rustc_expand: make proc-macro derive error translatable

---
 compiler/rustc_expand/locales/en-US.ftl | 3 +++
 compiler/rustc_expand/src/errors.rs     | 7 +++++++
 compiler/rustc_expand/src/proc_macro.rs | 2 +-
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_expand/locales/en-US.ftl b/compiler/rustc_expand/locales/en-US.ftl
index b475d285f6b..cfae781bdee 100644
--- a/compiler/rustc_expand/locales/en-US.ftl
+++ b/compiler/rustc_expand/locales/en-US.ftl
@@ -133,3 +133,6 @@ expand_trace_macro = trace_macro
 expand_proc_macro_panicked =
     proc macro panicked
     .help = message: {$message}
+
+expand_proc_macro_derive_tokens =
+    proc-macro derive produced unparseable tokens
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index 70ab222b484..e5102a952e7 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -390,3 +390,10 @@ pub(crate) struct ProcMacroPanicked {
 pub(crate) struct ProcMacroPanickedHelp {
     pub message: String,
 }
+
+#[derive(Diagnostic)]
+#[diag(expand_proc_macro_derive_tokens)]
+pub struct ProcMacroDeriveTokens {
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index cef64a10479..ddba1441719 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -176,7 +176,7 @@ impl MultiItemModifier for DeriveProcMacro {
 
         // fail if there have been errors emitted
         if ecx.sess.parse_sess.span_diagnostic.err_count() > error_count_before {
-            ecx.struct_span_err(span, "proc-macro derive produced unparseable tokens").emit();
+            ecx.sess.emit_err(errors::ProcMacroDeriveTokens { span });
         }
 
         ExpandResult::Ready(items)