Don’t print module selectors in more cases

There were a number of cases where Swift would emit module selectors into module interface files that it was subsequently unable to parse because the compiler at least temporarily represented them as dependent member types. Modify the carve-out so that if *any* of a type’s parents are generic parameters or archetypes, we don’t print a module selector on it.

Fixes rdar://166180424.

Author: beccadax

lib/AST/ASTPrinter.cpp

@@ -6139,11 +6139,15 @@ class TypePrinter : public TypeVisitor<TypePrinter, void, NonRecursivePrintOptio
 
   bool isMemberOfGenericParameter(TypeBase *T) {
     Type parent = nullptr;
-    if (auto alias = dyn_cast<TypeAliasType>(T))
+    if (auto alias = dyn_cast<TypeAliasType>(T))    // don't desugar
       parent = alias->getParent();
     else if (auto generic = T->getAs<AnyGenericType>())
       parent = generic->getParent();
-    return parent && parent->isTypeParameter();
+    else if (T->is<DependentMemberType>())
+      // Parent is always a generic parameter.
+      return true;
+    return parent && (parent->is<SubstitutableType>() ||
+                        isMemberOfGenericParameter(parent.getPointer()));
   }
 
   bool shouldPrintModuleSelector(TypeBase *T) {

test/ModuleInterface/module_selector.swift

@@ -125,13 +125,47 @@ public protocol Proto {
   // CHECK-DISABLED-SAME: TestCase.Struct<Swift.Int>
   typealias TypeAlias = Struct<Int>
 
+  // CHECK: typealias ID =
+  // CHECK-SAME: Self.AssocType.ID
+  typealias ID = AssocType.ID
+
   // CHECK: func requirement() -> Self.AssocType.ID
   func requirement() -> AssocType.ID
 
   // CHECK: func requirement2() ->
-  // CHECK-ENABLED: Self.TypeAlias.TestCase::Nested
-  // CHECK-DISABLED: Self.TypeAlias.Nested
+  // CHECK-SAME: Self.TypeAlias.Nested
   func requirement2() -> TypeAlias.Nested
 
   // CHECK: }
 }
+
+@available(SwiftStdlib 5.1, *)
+extension Proto {
+  public typealias Text = String
+}
+
+// Test cases from rdar://166180424
+
+// CHECK-LABEL: func fn3<T>(_ t: T) ->
+// CHECK-SAME: T.TypeAlias.Nested
+@available(SwiftStdlib 5.1, *)
+public func fn3<T: Proto>(_ t: T) -> T.TypeAlias.Nested { fatalError() }
+
+// CHECK-LABEL: struct ProtoSet
+@available(SwiftStdlib 5.1, *)
+public struct ProtoSet<T: Proto> {
+  // CHECK: let ids:
+  // CHECK-ENABLED-SAME: Swift::Set<T.ID>
+  // CHECK-DISABLED-SAME: Swift.Set<T.ID>
+  public let ids: Set<T.ID>
+
+  // CHECK: let texts:
+  // CHECK-ENABLED-SAME: Swift::Set<T.Text>
+  // CHECK-DISABLED-SAME: Swift.Set<T.Text>
+  public let texts: Set<T.Text>
+
+  // CHECK: let singleText:
+  // CHECK-SAME: T.Text
+  public let singleText: T.Text
+}
+