Cast to dynamic when the accessed member can't be found but the surrounding object can - fixes #786

There's probably a more specific condition which should trigger this if we look in Roslyn code

Author: GrahamTheCoder

CodeConverter/CSharp/ExpressionNodeVisitor.cs

@@ -420,6 +420,12 @@ public override async Task<CSharpSyntaxNode> VisitMemberAccessExpression(VBasic.
         }
         if (left == null) {
             left = await node.Expression.AcceptAsync<ExpressionSyntax>(TriviaConvertingExpressionVisitor);
+            if (left != null && _semanticModel.GetSymbolInfo(node) is {CandidateReason: CandidateReason.LateBound, CandidateSymbols.Length: 0}
+                             && _semanticModel.GetSymbolInfo(node.Expression).Symbol is {Kind: var expressionSymbolKind}
+                             && expressionSymbolKind != SymbolKind.ErrorType
+                             && _semanticModel.GetOperation(node) is IDynamicMemberReferenceOperation) {
+                left = SyntaxFactory.ParenthesizedExpression(SyntaxFactory.CastExpression(SyntaxFactory.ParseTypeName("dynamic"), left));
+            }
         }
         if (left == null) {
             if (IsSubPartOfConditionalAccess(node)) {

Tests/CSharp/ExpressionTests/ExpressionTests.cs

@@ -43,6 +43,43 @@ private void TestMethod(string a)
 }");
     }
 
+    [Fact]
+    public async Task DynamicTestAsync()
+    {
+        await TestConversionVisualBasicToCSharpAsync(@"
+Public Class C
+    Public Function IsPointWithinBoundaryBox(ByVal dblLat As Double, dblLon As Double, ByVal boundbox As Object) As Boolean
+        If boundbox IsNot Nothing Then
+            Dim boolInLatBounds As Boolean = (dblLat <= boundbox.north) And (dblLat >= boundbox.south) 'Less then highest (northmost) lat, AND more than lowest (southmost) lat
+            Dim boolInLonBounds As Boolean = (dblLon >= boundbox.west) And (dblLon <= boundbox.east) 'More than lowest (westmost) lat, AND less than highest (eastmost) lon
+            Return boolInLatBounds And boolInLonBounds
+        Else
+            'Throw New Exception(""boundbox is null."")
+        End If
+        Return False
+    End Function
+End Class
+", @"using Microsoft.VisualBasic.CompilerServices; // Install-Package Microsoft.VisualBasic
+
+public partial class C
+{
+    public bool IsPointWithinBoundaryBox(double dblLat, double dblLon, object boundbox)
+    {
+        if (boundbox is not null)
+        {
+            bool boolInLatBounds = Conversions.ToBoolean(Operators.AndObject(Operators.ConditionalCompareObjectLessEqual(dblLat, ((dynamic)boundbox).north, false), Operators.ConditionalCompareObjectGreaterEqual(dblLat, ((dynamic)boundbox).south, false))); // Less then highest (northmost) lat, AND more than lowest (southmost) lat
+            bool boolInLonBounds = Conversions.ToBoolean(Operators.AndObject(Operators.ConditionalCompareObjectGreaterEqual(dblLon, ((dynamic)boundbox).west, false), Operators.ConditionalCompareObjectLessEqual(dblLon, ((dynamic)boundbox).east, false))); // More than lowest (westmost) lat, AND less than highest (eastmost) lon
+            return boolInLatBounds & boolInLonBounds;
+        }
+        else
+        {
+            // Throw New Exception(""boundbox is null."")
+        }
+        return false;
+    }
+}");
+    }
+
     [Fact]
     public async Task ConversionOfNotUsesParensIfNeededAsync()
     {

Tests/CSharp/StandaloneStatementTests.cs

@@ -135,12 +135,12 @@ End If
     var cmccIds = new List<int>();
     foreach (var scr in _sponsorPayment.SponsorClaimRevisions)
     {
-        foreach (var claim in (IEnumerable)scr.Claims)
+        foreach (var claim in (IEnumerable)((dynamic)scr).Claims)
         {
-            if (claim.ClaimSummary is ClaimSummary)
+            if (((dynamic)claim).ClaimSummary is ClaimSummary)
             {
                 {
-                    var withBlock = (ClaimSummary)claim.ClaimSummary;
+                    var withBlock = (ClaimSummary)((dynamic)claim).ClaimSummary;
                     cmccIds.AddRange(withBlock.UnpaidClaimMealCountCalculationsIds);
                 }
             }
@@ -151,9 +151,8 @@ End If
 2 source compilation errors:
 BC30451: '_sponsorPayment' is not declared. It may be inaccessible due to its protection level.
 BC30002: Type 'ClaimSummary' is not defined.
-3 target compilation errors:
+2 target compilation errors:
 CS0103: The name '_sponsorPayment' does not exist in the current context
-CS1061: 'object' does not contain a definition for 'ClaimSummary' and no accessible extension method 'ClaimSummary' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)
 CS0246: The type or namespace name 'ClaimSummary' could not be found (are you missing a using directive or an assembly reference?)");
     }
 }