Added fix-it to add the @unchecked Sendable conformance if it is not re-stated (swiftlang#75233)

Co-authored-by: Timur Guliamov <[email protected]>

Author: tplaymeow

lib/Sema/TypeCheckConcurrency.cpp

@@ -6244,8 +6244,9 @@ bool swift::checkSendableConformance(
         return false;
     }
 
-    nominal->diagnose(diag::restate_unchecked_sendable,
-                      nominal->getName());
+    auto diag =
+        nominal->diagnose(diag::restate_unchecked_sendable, nominal->getName());
+    addSendableFixIt(nominal, diag, /*unchecked=*/true);
     return false;
   }
 

test/Concurrency/concurrent_value_checking.swift

@@ -361,7 +361,7 @@ class C5: @unchecked Sendable {
   var x: Int = 0 // okay
 }
 
-// expected-warning@+1 {{class 'C6' must restate inherited '@unchecked Sendable' conformance}}
+// expected-warning@+1 {{class 'C6' must restate inherited '@unchecked Sendable' conformance}}{{13-13=, @unchecked Sendable}}
 class C6: C5 {
   var y: Int = 0 // still okay, it's unsafe
 }