Intellisense not showing methods from the Base class in Signature Help

src/OmniSharp.Roslyn.CSharp/Services/Signatures/SignatureHelpService.cs

@@ -2,6 +2,7 @@
 using System.Composition;
 using System.Linq;
 using System.Threading.Tasks;
+using System.Collections.Immutable;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Text;
@@ -59,7 +60,7 @@ public async Task<SignatureHelpResponse> Handle(SignatureHelpRequest request)
             foreach (var invocation in invocations)
             {
                 var types = invocation.ArgumentTypes;
-                foreach (var methodOverload in GetMethodOverloads(invocation.SemanticModel, invocation.Receiver))
+                foreach (var methodOverload in invocation.SemanticModel.GetMemberGroup(invocation.Receiver).OfType<IMethodSymbol>())
                 {
                     var signature = BuildSignature(methodOverload);
                     signaturesSet.Add(signature);
@@ -115,27 +116,6 @@ private async Task<InvocationContext> GetInvocation(Document document, Request r
             return null;
         }
 
-        private IEnumerable<IMethodSymbol> GetMethodOverloads(SemanticModel semanticModel, SyntaxNode node)
-        {
-            ISymbol symbol = null;
-            var symbolInfo = semanticModel.GetSymbolInfo(node);
-            if (symbolInfo.Symbol != null)
-            {
-                symbol = symbolInfo.Symbol;
-            }
-            else if (!symbolInfo.CandidateSymbols.IsEmpty)
-            {
-                symbol = symbolInfo.CandidateSymbols.First();
-            }
-
-            if (symbol == null || symbol.ContainingType == null)
-            {
-                return new IMethodSymbol[] { };
-            }
-
-            return symbol.ContainingType.GetMembers(symbol.Name).OfType<IMethodSymbol>();
-        }
-
         private int InvocationScore(IMethodSymbol symbol, IEnumerable<TypeInfo> types)
         {
             var parameters = GetParameters(symbol);
@@ -162,7 +142,7 @@ private int InvocationScore(IMethodSymbol symbol, IEnumerable<TypeInfo> types)
                 }
             }
 
-            return score;
+            return score; 
         }
 
         private static SignatureHelpItem BuildSignature(IMethodSymbol symbol)

tests/OmniSharp.Roslyn.CSharp.Tests/SignatureHelpFacts.cs

@@ -474,13 +474,69 @@ public Program(Program p, int n)
     {
     }
 }";
-
             var actual = await GetSignatureHelp(source);
             Assert.Equal(3, actual.Signatures.Count());
             Assert.Equal(1, actual.ActiveParameter);
             Assert.Contains("ctor2", actual.Signatures.ElementAt(actual.ActiveSignature).Documentation);
         }
 
+        [Fact]
+        public async Task SignatureHelpForOverloadedMethodsInheritance()
+        {
+            const string source =
+@"public class MyBase
+{
+    public void MyMethod(int a) { }
+    public void MyMethod(int a, int b) { }
+}
+
+public class Class1 : MyBase
+{
+    public void MyMethod(int a, int b, int c) { }
+    public void MyMethod(int a, int b, int c, int d) { }
+}
+
+public class Class2
+{
+    public void foo()
+    {
+        Class1 c1 = new Class1();
+        c1.MyMethod($$);
+    }
+
+ }";
+            var actual = await GetSignatureHelp(source);
+            Assert.Equal(4, actual.Signatures.Count());
+        }
+
+        [Fact]
+        public async Task SignatureHelpForOverloadedInaccesibleMethods()
+        {
+            const string source =
+@"public class MyBase
+{
+    private void MyMethod(int a) { }
+}
+
+public class Class1 : MyBase
+{
+    public void MyMethod(int a, int b, int c) { }
+    protected void MyMethod(int a, int b, int c, int d) { }
+}
+
+public class Class2
+{
+    public void foo()
+    {
+        Class1 c1 = new Class1();
+        c1.MyMethod($$);
+    }
+
+ }";
+            var actual = await GetSignatureHelp(source);
+            Assert.Single(actual.Signatures);
+        }
+
         [Fact]
         public async Task SkipReceiverOfExtensionMethods()
         {