[Serialization] Use getAllMembers() to eliminate nondeterminism.

When serializing the members of a nominal type or extension, use
`getAllMembers()` instead of `getMembers()` to provide a deterministic
ordering.

Fixes rdar://63294687.

(cherry picked from commit ce12778)

Author: DougGregor

lib/Serialization/Serialization.cpp

@@ -2711,7 +2711,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
   /// \param members The decls within the context.
   /// \param isClass True if the context could be a class context (class,
   ///        class extension, or protocol).
-  void writeMembers(DeclID parentID, DeclRange members, bool isClass) {
+  void writeMembers(DeclID parentID, ArrayRef<Decl *> members, bool isClass) {
     using namespace decls_block;
 
     SmallVector<DeclID, 16> memberIDs;
@@ -2852,7 +2852,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
 
     SmallVector<DeclID, 16> witnessIDs;
 
-    for (auto member : proto->getMembers()) {
+    for (auto member : proto->getAllMembers()) {
       if (auto *value = dyn_cast<ValueDecl>(member)) {
         auto witness = proto->getDefaultWitness(value);
         if (!witness)
@@ -3013,7 +3013,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     for (auto *genericParams : llvm::reverse(allGenericParams))
       writeGenericParams(genericParams);
 
-    writeMembers(id, extension->getMembers(), isClassExtension);
+    writeMembers(id, extension->getAllMembers(), isClassExtension);
     S.writeConformances(conformances, S.DeclTypeAbbrCodes);
   }
 
@@ -3229,7 +3229,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
 
 
     writeGenericParams(theStruct->getGenericParams());
-    writeMembers(id, theStruct->getMembers(), false);
+    writeMembers(id, theStruct->getAllMembers(), false);
     S.writeConformances(conformances, S.DeclTypeAbbrCodes);
   }
 
@@ -3286,7 +3286,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
                             inheritedAndDependencyTypes);
 
     writeGenericParams(theEnum->getGenericParams());
-    writeMembers(id, theEnum->getMembers(), false);
+    writeMembers(id, theEnum->getAllMembers(), false);
     S.writeConformances(conformances, S.DeclTypeAbbrCodes);
   }
 
@@ -3345,7 +3345,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
                             inheritedAndDependencyTypes);
 
     writeGenericParams(theClass->getGenericParams());
-    writeMembers(id, theClass->getMembers(), true);
+    writeMembers(id, theClass->getAllMembers(), true);
     S.writeConformances(conformances, S.DeclTypeAbbrCodes);
   }
 
@@ -3394,7 +3394,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     writeGenericParams(proto->getGenericParams());
     S.writeGenericRequirements(
       proto->getRequirementSignature(), S.DeclTypeAbbrCodes);
-    writeMembers(id, proto->getMembers(), true);
+    writeMembers(id, proto->getAllMembers(), true);
     writeDefaultWitnessTable(proto);
   }
 
@@ -5128,7 +5128,7 @@ static void collectInterestingNestedDeclarations(
 
     // Recurse into nested declarations.
     if (auto iterable = dyn_cast<IterableDeclContext>(member)) {
-      collectInterestingNestedDeclarations(S, iterable->getMembers(),
+      collectInterestingNestedDeclarations(S, iterable->getAllMembers(),
                                            operatorMethodDecls,
                                            objcMethods, nestedTypeDecls,
                                            derivativeConfigs,
@@ -5210,7 +5210,7 @@ void Serializer::writeAST(ModuleOrSourceFile DC) {
         if (auto bodyFP = IDC->getBodyFingerprint()) {
           declFingerprints.insert({addDeclRef(D), *bodyFP});
         }
-        collectInterestingNestedDeclarations(*this, IDC->getMembers(),
+        collectInterestingNestedDeclarations(*this, IDC->getAllMembers(),
                                              operatorMethodDecls, objcMethods,
                                              nestedTypeDecls,
                                              uniquedDerivativeConfigs);
@@ -5243,7 +5243,7 @@ void Serializer::writeAST(ModuleOrSourceFile DC) {
         if (auto bodyFP = IDC->getBodyFingerprint()) {
           declFingerprints.insert({addDeclRef(TD), *bodyFP});
         }
-        collectInterestingNestedDeclarations(*this, IDC->getMembers(),
+        collectInterestingNestedDeclarations(*this, IDC->getAllMembers(),
                                              operatorMethodDecls, objcMethods,
                                              nestedTypeDecls,
                                              uniquedDerivativeConfigs,