[CSSimplify] If pack type has holes - its shape is a hole

Propagating holes to the shape helps avoid spurious diagnostics
about same-shape requirement failures.

Resolves: rdar://107675464

lib/Sema/CSSimplify.cpp

@@ -13269,6 +13269,14 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyShapeOfConstraint(
       return formUnsolved();
   }
 
+  if (type1->hasPlaceholder()) {
+    if (!shouldAttemptFixes())
+      return SolutionKind::Error;
+
+    recordTypeVariablesAsHoles(type2);
+    return SolutionKind::Solved;
+  }
+
   auto shape = type1->getReducedShape();
   addConstraint(ConstraintKind::Bind, shape, type2, locator);
   return SolutionKind::Solved;