[Type checker] Add "all members" request.

Introduce an "all members" request to compute all of the members of a
given iterable declaration context in stable order. This builds on ABI
members so that it will also include, e.g., type aliases synthesized
for associated types.

Author: DougGregor

include/swift/AST/DeclContext.h

@@ -784,6 +784,12 @@ class IterableDeclContext {
   /// The resulting list of members will be stable across translation units.
   ArrayRef<Decl *> getABIMembers() const;
 
+  /// Get all of the members within this context, including any
+  /// implicitly-synthesized members.
+  ///
+  /// The resulting list of members will be stable across translation units.
+  ArrayRef<Decl *> getAllMembers() const;
+
   /// Retrieve the set of members in this context without loading any from the
   /// associated lazy loader; this should only be used as part of implementing
   /// abstractions on top of member loading, such as a name lookup table.

include/swift/AST/TypeCheckRequests.h

@@ -1238,6 +1238,24 @@ class ABIMembersRequest :
   bool isCached() const { return true; }
 };
 
+class AllMembersRequest :
+    public SimpleRequest<AllMembersRequest,
+                         ArrayRef<Decl *>(IterableDeclContext *),
+                         RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  // Evaluation.
+  ArrayRef<Decl *>
+  evaluate(Evaluator &evaluator, IterableDeclContext *idc) const;
+
+public:
+  bool isCached() const { return true; }
+};
+
 class IsImplicitlyUnwrappedOptionalRequest :
     public SimpleRequest<IsImplicitlyUnwrappedOptionalRequest,
                          bool(ValueDecl *),

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -67,6 +67,8 @@ SWIFT_REQUEST(TypeChecker, DynamicallyReplacedDeclRequest,
               Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, ABIMembersRequest,
               ArrayRef<Decl *>(IterableDeclContext *), Cached, NoLocationInfo)
+SWIFT_REQUEST(TypeChecker, AllMembersRequest,
+              ArrayRef<Decl *>(IterableDeclContext *), Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, SpecializeAttrTargetDeclRequest,
               ValueDecl *(const ValueDecl *, SpecializeAttr *),
               Cached, NoLocationInfo)

lib/AST/DeclContext.cpp

@@ -766,6 +766,14 @@ ArrayRef<Decl *> IterableDeclContext::getABIMembers() const {
       ArrayRef<Decl *>());
 }
 
+ArrayRef<Decl *> IterableDeclContext::getAllMembers() const {
+  ASTContext &ctx = getASTContext();
+  return evaluateOrDefault(
+      ctx.evaluator,
+      AllMembersRequest{const_cast<IterableDeclContext *>(this)},
+      ArrayRef<Decl *>());
+}
+
 void IterableDeclContext::addMemberPreservingSourceOrder(Decl *member) {
   auto &SM = getASTContext().SourceMgr;
 

lib/Sema/TypeCheckDecl.cpp

@@ -2550,14 +2550,23 @@ struct SortedDeclList {
 
 } // end namespace
 
-ArrayRef<Decl *>
-ABIMembersRequest::evaluate(
-    Evaluator &evaluator, IterableDeclContext *idc) const {
+namespace {
+  enum class MembersRequestKind {
+    ABI,
+    All,
+  };
+
+}
+
+/// Evaluate a request for a particular set of members of an iterable
+/// declaration context.
+static ArrayRef<Decl *> evaluateMembersRequest(
+  IterableDeclContext *idc, MembersRequestKind kind) {
   auto dc = cast<DeclContext>(idc->getDecl());
-  auto &Context = dc->getASTContext();
+  auto &ctx = dc->getASTContext();
   SmallVector<Decl *, 8> result;
 
-  // Esnure that we add any synthesized members.
+  // Ensure that we add any synthesized members.
   if (dc->getParentSourceFile()) {
     auto nominal = dyn_cast<NominalTypeDecl>(idc);
 
@@ -2567,20 +2576,43 @@ ABIMembersRequest::evaluate(
       TypeChecker::addImplicitConstructors(nominal);
     }
 
-    // Force any derivable conformances in this context. This ensures that any
-    // synthesized members will approach in the member list.
+    // Force any conformances that may introduce more members.
     for (auto conformance : idc->getLocalConformances()) {
-      if (conformance->getState() == ProtocolConformanceState::Incomplete &&
-          conformance->getProtocol()->getKnownDerivableProtocolKind())
-        TypeChecker::checkConformance(conformance->getRootNormalConformance());
+      auto proto = conformance->getProtocol();
+      bool isDerivable =
+        conformance->getState() == ProtocolConformanceState::Incomplete &&
+        proto->getKnownDerivableProtocolKind();
+
+      switch (kind) {
+      case MembersRequestKind::ABI:
+        // Force any derivable conformances in this context.
+        if (isDerivable)
+          break;
+
+        continue;
+
+      case MembersRequestKind::All:
+        // Force any derivable conformances.
+        if (isDerivable)
+          break;
+
+        // If there are any associated types in the protocol, they might add
+        // type aliases here.
+        if (!proto->getAssociatedTypeMembers().empty())
+          break;
+
+        continue;
+      }
+
+      TypeChecker::checkConformance(conformance->getRootNormalConformance());
     }
 
     // If the type conforms to Encodable or Decodable, even via an extension,
     // the CodingKeys enum is synthesized as a member of the type itself.
     // Force it into existence.
     if (nominal) {
       (void) evaluateOrDefault(
-        Context.evaluator,
+        ctx.evaluator,
         ResolveImplicitMemberRequest{nominal,
                    ImplicitMemberAction::ResolveCodingKeys},
         {});
@@ -2589,7 +2621,7 @@ ABIMembersRequest::evaluate(
     // If the decl has a @main attribute, we need to force synthesis of the
     // $main function.
     (void) evaluateOrDefault(
-        Context.evaluator,
+        ctx.evaluator,
         SynthesizeMainFunctionRequest{const_cast<Decl *>(idc->getDecl())},
         nullptr);
 
@@ -2633,7 +2665,19 @@ ABIMembersRequest::evaluate(
       result.push_back(pair.second);
   }
 
-  return Context.AllocateCopy(result);
+  return ctx.AllocateCopy(result);
+}
+
+ArrayRef<Decl *>
+ABIMembersRequest::evaluate(
+    Evaluator &evaluator, IterableDeclContext *idc) const {
+  return evaluateMembersRequest(idc, MembersRequestKind::ABI);
+}
+
+ArrayRef<Decl *>
+AllMembersRequest::evaluate(
+    Evaluator &evaluator, IterableDeclContext *idc) const {
+  return evaluateMembersRequest(idc, MembersRequestKind::All);
 }
 
 bool TypeChecker::isPassThroughTypealias(TypeAliasDecl *typealias,

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2129,7 +2129,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     TypeChecker::checkDeclAttributes(CD);
 
-    for (Decl *Member : CD->getABIMembers())
+    for (Decl *Member : CD->getAllMembers())
       visit(Member);
 
     TypeChecker::checkPatternBindingCaptures(CD);