Handle warnings, and add a warning if a function parameter has an unknown type

Upsilon/Binder/Binder.cs

@@ -46,6 +46,7 @@ namespace Upsilon.Binder
                 foreach (var valueParameter in unboundFunctionStatement.Value.Parameters)
                 {
                     Scope.AssignToNearest(valueParameter.VariableSymbol);
+                    _diagnostics.LogUnknownVariableType(valueParameter.VariableSymbol.Name, valueParameter.Span);
                 }
                 unboundFunctionStatement.Value.Block =
                     (BoundBlockStatement) BindBlockStatement(unboundFunctionStatement.Value.UnboundBlock);

Upsilon/Diagnostics.cs

@@ -9,7 +9,8 @@ namespace Upsilon
     public class Diagnostics
     {
         public SourceText ScriptString { get; }
-        public readonly List<DiagnosticsMessage> Messages = new List<DiagnosticsMessage>();
+        public readonly List<DiagnosticsMessage> Errors = new List<DiagnosticsMessage>();
+        public readonly List<DiagnosticsMessage> Warnings = new List<DiagnosticsMessage>();
         public bool ThrowsOnError { get; }
 
         public Diagnostics(SourceText scriptString, bool throwsOnError)
@@ -20,7 +21,10 @@ namespace Upsilon
 
         public void Log(DiagnosticLevel level, string message, TextSpan location)
         {
-            Messages.Add(new DiagnosticsMessage(this, level, message, location));
+            if (level == DiagnosticLevel.Error)
+                Errors.Add(new DiagnosticsMessage(this, level, message, location));
+            else if (level == DiagnosticLevel.Warning)
+                Warnings.Add(new DiagnosticsMessage(this, level, message, location));
         }
 
         public void LogError(string message, TextSpan location)
@@ -34,6 +38,11 @@ namespace Upsilon
             Log(DiagnosticLevel.Error, message, location);
         }
 
+        public void LogWarning(string message, TextSpan location)
+        {
+            Log(DiagnosticLevel.Warning, message, location);
+        }
+
         public void LogBadCharacter(TextSpan location, SyntaxKind expectedToken, SyntaxKind currentKind)
         {
             LogError($"Invalid character found. Expected: '{expectedToken}', Got: '{currentKind}'", location);
@@ -87,18 +96,25 @@ namespace Upsilon
         {
             LogError($"Cannot index type '{expressionType}' with type '{indexType}'", span);
         }
+
+        public void LogUnknownVariableType(string variableName, TextSpan span)
+        {
+            LogWarning(
+                $"Variable '{variableName}' has an unknown variable type, and as such errors won't be visible before evaluation.",
+                span);
+        }
     }
 
     public class DiagnosticsMessage
     {
         public Diagnostics Diagnostics { get; }
-        private readonly DiagnosticLevel _diagnosticLevel;
+        public DiagnosticLevel DiagnosticLevel { get; }
         public string Message { get; }
         public TextSpan Span { get; }
 
         public DiagnosticsMessage(Diagnostics diagnostics, DiagnosticLevel diagnosticLevel, string message, TextSpan span)
         {
-            _diagnosticLevel = diagnosticLevel;
+            DiagnosticLevel = diagnosticLevel;
             Diagnostics = diagnostics;
             Message = message;
             Span = span;

Upsilon/Evaluator/Script.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using Upsilon.BaseTypes;
 using Upsilon.Binder;