Simplify and reduce amount of work performed by SourcePropertySymbolBase constructor.

src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs

@@ -1628,7 +1628,7 @@ private static bool AccessingAutoPropertyFromConstructor(BoundExpression receive
             var propertyIsStatic = propertySymbol.IsStatic;
 
             return (object)sourceProperty != null &&
-                    sourceProperty.IsAutoProperty &&
+                    sourceProperty.IsAutoPropertyWithGetAccessor &&
                     TypeSymbol.Equals(sourceProperty.ContainingType, fromMember.ContainingType, TypeCompareKind.ConsiderEverything2) &&
                     IsConstructorOrField(fromMember, isStatic: propertyIsStatic) &&
                     (propertyIsStatic || receiver.Kind == BoundKind.ThisReference);

src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs

@@ -1754,7 +1754,7 @@ syntaxNode is ConstructorDeclarationSyntax constructorSyntax &&
                 else
                 {
                     var property = sourceMethod.AssociatedSymbol as SourcePropertySymbolBase;
-                    if ((object)property != null && property.IsAutoProperty)
+                    if ((object)property != null && property.IsAutoPropertyWithGetAccessor)
                     {
                         return MethodBodySynthesizer.ConstructAutoPropertyAccessorBody(sourceMethod);
                     }

src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_AssignmentOperator.cs

@@ -299,7 +299,7 @@ private BoundExpression MakePropertyAssignment(
             if (setMethod is null)
             {
                 var autoProp = (SourcePropertySymbolBase)property;
-                Debug.Assert(autoProp.IsAutoProperty,
+                Debug.Assert(autoProp.IsAutoPropertyWithGetAccessor,
                     "only autoproperties can be assignable without having setters");
 
                 var backingField = autoProp.BackingField;

src/Compilers/CSharp/Portable/Symbols/CompletionPart.cs

@@ -91,11 +91,16 @@ internal enum CompletionPart
         TypeParameterSymbolAll = Attributes | TypeParameterConstraints,
 
         // For property symbols
-        StartPropertyParameters = 1 << 4,
-        FinishPropertyParameters = 1 << 5,
-        StartPropertyType = 1 << 6,
-        FinishPropertyType = 1 << 7,
-        PropertySymbolAll = Attributes | StartPropertyParameters | FinishPropertyParameters | StartPropertyType | FinishPropertyType,
+        StartPropertyEnsureSignature = 1 << 4,
+        FinishPropertyEnsureSignature = 1 << 5,
+        StartPropertyParameters = 1 << 6,
+        FinishPropertyParameters = 1 << 7,
+        StartPropertyType = 1 << 8,
+        FinishPropertyType = 1 << 9,
+        StartPropertyFinalCompletion = 1 << 10,
+        FinishPropertyFinalCompletion = 1 << 11,
+        PropertySymbolAll = Attributes | StartPropertyEnsureSignature | FinishPropertyEnsureSignature | StartPropertyParameters | FinishPropertyParameters |
+                            StartPropertyType | FinishPropertyType | StartPropertyFinalCompletion | FinishPropertyFinalCompletion,
 
         // For alias symbols
         AliasTarget = 1 << 4,

src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberContainerSymbol.cs

@@ -3291,15 +3291,15 @@ ImmutableArray<PropertySymbol> addProperties(ImmutableArray<ParameterSymbol> rec
                     }
                     if (existingMember is null)
                     {
-                        addProperty(new SynthesizedRecordPropertySymbol(this, syntax, param, isOverride: false, diagnostics));
+                        addProperty(new SynthesizedRecordPropertySymbol(this, syntax, param, isOverride: false));
                     }
                     else if (existingMember is PropertySymbol { IsStatic: false, GetMethod: { } } prop
                         && prop.TypeWithAnnotations.Equals(param.TypeWithAnnotations, TypeCompareKind.AllIgnoreOptions))
                     {
                         // There already exists a member corresponding to the candidate synthesized property.
                         if (isInherited && prop.IsAbstract)
                         {
-                            addProperty(new SynthesizedRecordPropertySymbol(this, syntax, param, isOverride: true, diagnostics));
+                            addProperty(new SynthesizedRecordPropertySymbol(this, syntax, param, isOverride: true));
                         }
                         else
                         {
@@ -3320,6 +3320,8 @@ void addProperty(SynthesizedRecordPropertySymbol property)
                     {
                         existingOrAddedMembers.Add(property);
                         members.Add(property);
+                        Debug.Assert(property.GetMethod is object);
+                        Debug.Assert(property.SetMethod is object);
                         members.Add(property.GetMethod);
                         members.Add(property.SetMethod);
                         members.Add(property.BackingField);
@@ -3393,7 +3395,7 @@ PropertySymbol addEqualityContract()
 
                 if (!memberSignatures.TryGetValue(targetProperty, out Symbol? existingEqualityContractProperty))
                 {
-                    equalityContract = new SynthesizedRecordEqualityContractProperty(this, diagnostics);
+                    equalityContract = new SynthesizedRecordEqualityContractProperty(this);
                     members.Add(equalityContract);
                     members.Add(equalityContract.GetMethod);
                 }