Migrate 'missing fn lang items' diagnostic

Author: clubby789

compiler/rustc_hir_typeck/messages.ftl

@@ -72,6 +72,9 @@ hir_typeck_lang_start_incorrect_ret_ty = the return type of the `start` lang ite
 hir_typeck_method_call_on_unknown_raw_pointee =
     cannot call a method on a raw pointer with an unknown pointee type
 
+hir_typeck_missing_fn_lang_items = failed to find an overloaded call trait for closure call
+    .help = make sure the `fn`/`fn_mut`/`fn_once` lang items are defined and have correctly defined `call`/`call_mut`/`call_once` methods
+
 hir_typeck_missing_parentheses_in_range = can't call method `{$method_name}` on type `{$ty_str}`
 
 hir_typeck_no_associated_item = no {$item_kind} named `{$item_name}` found for {$ty_prefix} `{$ty_str}`{$trait_missing_method ->

compiler/rustc_hir_typeck/src/callee.rs

@@ -607,7 +607,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ty: match &unit_variant {
                 Some((_, kind, path)) => format!("{kind} `{path}`"),
                 None => format!("`{callee_ty}`"),
-            }
+            },
         });
         if callee_ty.references_error() {
             err.downgrade_to_delayed_bug();
@@ -882,15 +882,7 @@ impl<'a, 'tcx> DeferredCallResolution<'tcx> {
             None => {
                 // This can happen if `#![no_core]` is used and the `fn/fn_mut/fn_once`
                 // lang items are not defined (issue #86238).
-                let mut err = fcx.inh.tcx.sess.struct_span_err(
-                    self.call_expr.span,
-                    "failed to find an overloaded call trait for closure call",
-                );
-                err.help(
-                    "make sure the `fn`/`fn_mut`/`fn_once` lang items are defined \
-                     and have correctly defined `call`/`call_mut`/`call_once` methods",
-                );
-                err.emit();
+                fcx.inh.tcx.sess.emit_err(errors::MissingFnLangItems { span: self.call_expr.span });
             }
         }
     }

compiler/rustc_hir_typeck/src/errors.rs

@@ -83,6 +83,14 @@ pub struct MethodCallOnUnknownRawPointee {
     pub span: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(hir_typeck_missing_fn_lang_items)]
+#[help]
+pub struct MissingFnLangItems {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(hir_typeck_functional_record_update_on_non_struct, code = "E0436")]
 pub struct FunctionalRecordUpdateOnNonStruct {