Several bug fixes

src/Analysis/Engine/Impl/Analyzer/DDG.cs

@@ -441,14 +441,14 @@ private bool TryImportModule(string modName, bool forceAbsolute, out ModuleRefer
                 if (gotAllParents && ProjectState.Modules.TryImport(name, out modRef)) {
                     moduleRef = modRef;
                     (lastParent as BuiltinModule)?.AddChildModule(remainingParts[0], moduleRef.AnalysisModule);
-                    _unit.DeclaringModule.AddModuleReference(moduleRef);
+                    _unit.DeclaringModule.AddModuleReference(modName, moduleRef);
                     remainingParts = null;
                     return true;
                 }
             }
 
             if (moduleRef?.Module != null) {
-                _unit.DeclaringModule.AddModuleReference(moduleRef);
+                _unit.DeclaringModule.AddModuleReference(modName, moduleRef);
                 return true;
             }
             return false;

src/Analysis/Engine/Impl/Infrastructure/Check.cs

@@ -17,23 +17,23 @@ public static void FieldType<T>(string fieldName, object fieldValue) {
 
         [DebuggerStepThrough]
         public static void ArgumentOfType<T>(string argumentName, object argument, [CallerMemberName] string callerName = null) {
-            ArgumentNull(argumentName, argument);
+            ArgumentNotNull(argumentName, argument);
 
             if (!(argument is T)) {
                 throw new ArgumentException($"Argument {argumentName} of method {callerName} must be of type {typeof(T)}");
             }
         }
 
         [DebuggerStepThrough]
-        public static void ArgumentNull(string argumentName, object argument) {
+        public static void ArgumentNotNull(string argumentName, object argument) {
             if (argument is null) {
                 throw new ArgumentNullException(argumentName);
             }
         }
 
         [DebuggerStepThrough]
         public static void ArgumentNotNullOrEmpty(string argumentName, string argument) {
-            ArgumentNull(argumentName, argument);
+            ArgumentNotNull(argumentName, argument);
 
             if (string.IsNullOrEmpty(argument)) {
                 throw new ArgumentException(argumentName);

src/Analysis/Engine/Impl/Infrastructure/Disposable.cs

@@ -30,7 +30,7 @@ public static class Disposable {
         /// <returns>The disposable object that runs the given action upon disposal.</returns>
         /// <exception cref="T:System.ArgumentNullException"><paramref name="dispose" /> is null.</exception>
         public static IDisposable Create(Action dispose) {
-            Check.ArgumentNull(nameof(dispose), dispose);
+            Check.ArgumentNotNull(nameof(dispose), dispose);
             return new AnonymousDisposable(dispose);
         }
 
@@ -41,7 +41,7 @@ public static IDisposable Create(Action dispose) {
         /// <returns>The disposable object that disposes wrapped object.</returns>
         /// <exception cref="T:System.ArgumentNullException"><paramref name="disposable" /> is null.</exception>
         public static IDisposable Create(IDisposable disposable) {
-            Check.ArgumentNull(nameof(disposable), disposable);
+            Check.ArgumentNotNull(nameof(disposable), disposable);
             return new DisposableWrapper(disposable);
         }
 

src/Analysis/Engine/Impl/MemberResult.cs

@@ -160,15 +160,17 @@ private PythonMemberType GetMemberType() {
             return result;
         }
 
-        public override bool Equals(object obj) {
-            if (!(obj is MemberResult)) {
-                return false;
+        public bool Equals(MemberResult other) => string.Equals(Name, other.Name) && Equals(Scope, other.Scope);
+
+        public override bool Equals(object obj) => obj is MemberResult other && Equals(other);
+
+        public override int GetHashCode() {
+            unchecked {
+                return ((Name != null ? Name.GetHashCode() : 0) * 397) ^ (Scope != null ? Scope.GetHashCode() : 0);
             }
-            return Name == ((MemberResult)obj).Name;
         }
 
-        public static bool operator ==(MemberResult x, MemberResult y) => x.Name == y.Name;
-        public static bool operator !=(MemberResult x, MemberResult y) => x.Name != y.Name;
-        public override int GetHashCode() => Name.GetHashCode();
+        public static bool operator ==(MemberResult left, MemberResult right) => left.Equals(right);
+        public static bool operator !=(MemberResult left, MemberResult right) => !left.Equals(right);
     }
 }

src/Analysis/Engine/Impl/Parsing/Ast/DottedName.cs

@@ -22,16 +22,14 @@ namespace Microsoft.PythonTools.Parsing.Ast {
     public class DottedName : Node {
         private readonly NameExpression[] _names;
 
-        public DottedName(NameExpression[] names) {
+        public DottedName(NameExpression[]/*!*/ names) {
             _names = names;
         }
 
-        public IList<NameExpression> Names {
-            get { return _names; }
-        }
+        public IList<NameExpression> Names => _names;
 
         public virtual string MakeString() {
-            if (_names.Length == 0) return String.Empty;
+            if (_names.Length == 0) return string.Empty;
 
             StringBuilder ret = new StringBuilder(_names[0].Name);
             for (int i = 1; i < _names.Length; i++) {

src/Analysis/Engine/Impl/Parsing/Ast/FromImportStatement.cs

@@ -25,7 +25,7 @@ public class FromImportStatement : Statement {
         private static readonly string[] _star = new[] { "*" };
         private PythonVariable[] _variables;
 
-        public FromImportStatement(ModuleName root, NameExpression/*!*/[] names, NameExpression[] asNames, bool fromFuture, bool forceAbsolute, int importIndex) {
+        public FromImportStatement(ModuleName/*!*/ root, NameExpression/*!*/[] names, NameExpression[] asNames, bool fromFuture, bool forceAbsolute, int importIndex) {
             Root = root;
             Names = names;
             AsNames = asNames;

src/Analysis/Engine/Impl/Parsing/Ast/ModuleName.cs

@@ -16,7 +16,7 @@
 
 namespace Microsoft.PythonTools.Parsing.Ast {
     public class ModuleName : DottedName {
-        public ModuleName(NameExpression[] names)
+        public ModuleName(NameExpression[]/*!*/ names)
             : base(names) {
         }
     }

src/Analysis/Engine/Impl/Parsing/Ast/RelativeModuleName.cs

@@ -18,26 +18,18 @@
 
 namespace Microsoft.PythonTools.Parsing.Ast {
     public class RelativeModuleName : ModuleName {
-        private readonly int _dotCount;
-
-        public RelativeModuleName(NameExpression[] names, int dotCount)
+        public RelativeModuleName(NameExpression[]/*!*/ names, int dotCount)
             : base(names) {
-            _dotCount = dotCount;
+            DotCount = dotCount;
         }
 
-        public override string MakeString() {
-            return new string('.', DotCount) + base.MakeString();
-        }
+        public override string MakeString() => new string('.', DotCount) + base.MakeString();
 
-        public int DotCount {
-            get {
-                return _dotCount;
-            }
-        }
+        public int DotCount { get; }
 
         internal override void AppendCodeString(StringBuilder res, PythonAst ast, CodeFormattingOptions format) {
             var whitespace = this.GetListWhiteSpace(ast);
-            for (int i = 0; i < _dotCount; i++) {
+            for (int i = 0; i < DotCount; i++) {
                 if (whitespace != null) {
                     res.Append(whitespace[i]);
                 }

src/Analysis/Engine/Impl/ProjectEntry.cs

@@ -268,6 +268,7 @@ private void Parse(bool enqueueOnly, CancellationToken cancel) {
             MyScope.Scope.ClearNodeValues();
             MyScope.Scope.ClearLinkedVariables();
             MyScope.Scope.ClearVariables();
+            MyScope.ClearReferencedModules();
             MyScope.ClearUnresolvedModules();
             _unit.State.ClearDiagnostics(this);
 
@@ -366,10 +367,7 @@ public void Dispose() {
                     }
                 }
 
-                foreach (var moduleReference in MyScope.ModuleReferences.ToList()) {
-                    MyScope.RemoveModuleReference(moduleReference);
-                }
-
+                MyScope.ClearReferencedModules();
                 NewParseTree -= NewParseTree;
                 NewAnalysis -= NewAnalysis;
             }