Various fixes (#450)

* Update Draco.LanguageServer.csproj

* Crashbug fixes

* More crashbugs

* Update TypeProvider.cs

src/Draco.Compiler/Api/CodeCompletion/SignatureService.cs

@@ -39,11 +39,17 @@ public sealed class SignatureService
         var activeParam = separatorCount == paramCount - 1 ? paramCount - 1 : paramCount;
 
         // Select the best overload to show as default in the signature
+        // TODO: Improve this, this is really primitive
         var currentOverload = symbols.FirstOrDefault(x => x.Parameters.Length == paramCount && (separatorCount == paramCount - 1 || paramCount == 0));
         currentOverload ??= symbols.FirstOrDefault(x => x.Parameters.Length > paramCount);
         currentOverload ??= symbols.First();
         IParameterSymbol? currentParameter = null;
-        if (currentOverload.Parameters.Length != 0) currentParameter = currentOverload.Parameters[activeParam];
+        if (currentOverload.Parameters.Length != 0)
+        {
+            currentParameter = currentOverload.Parameters.Length > activeParam
+                ? currentOverload.Parameters[activeParam]
+                : currentOverload.Parameters[^1];
+        }
         // Return all the overloads
         return new SignatureItem(symbols, currentOverload, currentParameter);
     }

src/Draco.Compiler/Internal/Binding/SymbolResolutionErrors.cs

@@ -164,4 +164,13 @@ internal static class SymbolResolutionErrors
         severity: DiagnosticSeverity.Error,
         format: "the member {0} must be a gettable property",
         code: Code(17));
+
+    /// <summary>
+    /// The referenced assembly can not be found.
+    /// </summary>
+    public static readonly DiagnosticTemplate CanNotResolveReferencedAssembly = DiagnosticTemplate.Create(
+        title: "can not resolve referenced assembly",
+        severity: DiagnosticSeverity.Error,
+        format: "the referenced assembly {0} can not be resolved",
+        code: Code(18));
 }

src/Draco.Compiler/Internal/Symbols/Error/ErrorTypeSymbol.cs

@@ -1,3 +1,6 @@
+using Draco.Compiler.Internal.Symbols.Generic;
+using System.Collections.Immutable;
+
 namespace Draco.Compiler.Internal.Symbols.Error;
 
 /// <summary>
@@ -13,4 +16,7 @@ internal sealed class ErrorTypeSymbol(string name) : TypeSymbol
     public string DisplayName { get; } = name;
 
     public override string ToString() => this.DisplayName;
+
+    public override TypeSymbol GenericInstantiate(Symbol? containingSymbol, ImmutableArray<TypeSymbol> arguments) => this;
+    public override TypeSymbol GenericInstantiate(Symbol? containingSymbol, GenericContext context) => this;
 }

src/Draco.Compiler/Internal/Symbols/Metadata/TypeProvider.cs

@@ -6,6 +6,8 @@
 using System.Reflection;
 using System.Reflection.Metadata;
 using Draco.Compiler.Api;
+using Draco.Compiler.Api.Diagnostics;
+using Draco.Compiler.Internal.Binding;
 using Draco.Compiler.Internal.Symbols.Synthetized;
 
 namespace Draco.Compiler.Internal.Symbols.Metadata;
@@ -192,9 +194,19 @@ private TypeSymbol BuildTypeFromReference(MetadataReader reader, TypeReferenceHa
         if (!string.IsNullOrEmpty(@namespace)) parts.AddRange(@namespace.Split('.').Reverse());
         parts.Reverse();
 
-        // TODO: If we don't have the assembly report error
         var assemblyName = reader.GetAssemblyReference((AssemblyReferenceHandle)resolutionScope).GetAssemblyName();
-        var assembly = compilation.MetadataAssemblies.Single(x => AssemblyNamesEqual(x.AssemblyName, assemblyName));
+        var assembly = compilation.MetadataAssemblies.FirstOrDefault(x =>
+            AssemblyIsSufficient(assemblyName, x.AssemblyName));
+        if (assembly is null)
+        {
+            // The assembly for some reason isn't included, report it
+            compilation.GlobalDiagnosticBag.Add(Diagnostic.Create(
+                template: SymbolResolutionErrors.CanNotResolveReferencedAssembly,
+                location: Location.None,
+                formatArgs: assemblyName));
+            return WellKnownTypes.ErrorType;
+        }
+
         return assembly.RootNamespace.Lookup([.. parts]).OfType<TypeSymbol>().Single();
     }
 
@@ -226,7 +238,7 @@ private static string ConcatenateNamespaceAndName(string? @namespace, string nam
     // NOTE: For some reason we had to disregard public key token, otherwise some weird type referencing
     // case in the REPL with lists threw an exception
     // TODO: Could it be that we don't write the public key token in the type refs we use?
-    private static bool AssemblyNamesEqual(AssemblyName a, AssemblyName b) =>
-           a.Name == b.Name
-        && a.Version == b.Version;
+    private static bool AssemblyIsSufficient(AssemblyName wanted, AssemblyName got) =>
+           got.Name == wanted.Name
+        && got.Version >= wanted.Version;
 }

src/Draco.LanguageServer/Draco.LanguageServer.csproj

@@ -22,6 +22,7 @@
     <PackageReference Include="NuGet.Packaging" Version="6.11.0" ExcludeAssets="runtime" />
     <PackageReference Include="NuGet.Common" Version="6.11.0" ExcludeAssets="runtime" />
     <PackageReference Include="NuGet.Versioning" Version="6.11.0" ExcludeAssets="runtime" />
+    <PackageReference Include="NuGet.Configuration" Version="6.11.0" ExcludeAssets="runtime" />
   </ItemGroup>
 
 </Project>

src/Draco.LanguageServer/Translator.cs

@@ -119,7 +119,9 @@ or CompilerApi.CodeCompletion.CompletionKind.DeclarationKeyword
         CompilerApi.CodeCompletion.CompletionKind.ReferenceTypeName => LspModels.CompletionItemKind.Class,
         CompilerApi.CodeCompletion.CompletionKind.ValueTypeName => LspModels.CompletionItemKind.Struct,
 
-        _ => throw new System.ArgumentOutOfRangeException(nameof(kind)),
+        CompilerApi.CodeCompletion.CompletionKind.Operator => LspModels.CompletionItemKind.Operator,
+
+        _ => LspModels.CompletionItemKind.Text,
     };
 
     public static LspModels.SignatureHelp? ToLsp(CompilerApi.CodeCompletion.SignatureItem? item) => item is null ? null : new()