[ConstraintSystem] Attempt conjunction before closure result or generic parameter holes

Closure result type or generic parameter associated with such a location
could bw inferred from a body of a multi-statement closure (when inference
is enabled), so we need to give closure a chance to run before attemtping
a hole for such positions in diagnostic mode.

lib/Sema/CSStep.cpp

@@ -345,6 +345,19 @@ StepResult ComponentStep::take(bool prevFailed) {
   auto *disjunction = CS.selectDisjunction();
   auto bestBindings = CS.determineBestBindings();
 
+  if (CS.shouldAttemptFixes()) {
+    if ((bestBindings &&
+         (bestBindings->forClosureResult() ||
+          bestBindings->forGenericParameter()) &&
+         bestBindings->isHole()) &&
+        !disjunction) {
+      if (auto *conjunction = CS.selectConjunction()) {
+        return suspend(
+            std::make_unique<ConjunctionStep>(CS, conjunction, Solutions));
+      }
+    }
+  }
+
   if (bestBindings &&
       (!disjunction || bestBindings->favoredOverDisjunction(disjunction))) {
     // Produce a type variable step.