Merge pull request #67326 from xedin/rdar-110721928

[CSSimplify] Deplay member lookup until single-element tuple with pac…

Author: xedin

lib/Sema/CSSimplify.cpp

@@ -9378,6 +9378,17 @@ performMemberLookup(ConstraintKind constraintKind, DeclNameRef memberName,
     return result;
   }
 
+  // Delay member lookup until single-element tuple with pack expansion
+  // is sufficiently resolved.
+  if (isSingleUnlabeledPackExpansionTuple(instanceTy)) {
+    auto elementTy = instanceTy->castTo<TupleType>()->getElementType(0);
+    if (elementTy->is<TypeVariableType>()) {
+      MemberLookupResult result;
+      result.OverallResult = MemberLookupResult::Unsolved;
+      return result;
+    }
+  }
+
   // Okay, start building up the result list.
   MemberLookupResult result;
   result.OverallResult = MemberLookupResult::HasResults;

test/Constraints/pack-expansion-expressions.swift

@@ -707,3 +707,18 @@ do {
     test3(str: "", a, a)  // expected-error {{ambiguous use of 'test3'}}
   }
 }
+
+// rdar://112095973 - single-element tuples are not unwrapped in member references
+do {
+  struct V<Value> {
+    let key: Int
+  }
+
+  struct S<each T> {
+    let data: (repeat V<each T>)
+  }
+
+  func test<U>(_ value: S<U>) {
+    _ = value.data.key // Ok
+  }
+}