Move Name, Namespace and OwningType to DefType (#1553)

The motivation for this change is:
* To make the type name formatter general purpose (it can now handle
`NoMetadata` types)
* To make `NameMangler` able to mangle canon types and runtime
determined types without special casing

For situation where we have a NoMetadataType, the expectation is that
we're asking for the name for diagnostic purposes only (i.e. name
formatter wants it). In that case:
* In checked builds, the name can actually be retrieved from diagnostic
mapping tables, along with the owning type (we have a metadata TypeRef
for this).
* In the absence of diagnostic mapping tables, the name can be faked up
and the type pretended to be non-nested
("System.Runtime.NoMetadataTypes.EEType1234ABCD")

As an additional change, I'm also adding `Name` property on
`GenericParameterDesc`. We can compute a useful fallback value for this
in absence of metadata ("T" + index).

1 files changed, 5 insertions, 4 deletions

diff --git a/src/ILCompiler.MetadataTransform/src/ILCompiler/Metadata/Transform.Type.cs b/src/ILCompiler.MetadataTransform/src/ILCompiler/Metadata/Transform.Type.cs
index 6869aefa3..60ae0e148 100644
--- a/src/ILCompiler.MetadataTransform/src/ILCompiler/Metadata/Transform.Type.cs
+++ b/src/ILCompiler.MetadataTransform/src/ILCompiler/Metadata/Transform.Type.cs
@@ -166,7 +166,7 @@ namespace ILCompiler.Metadata
             // references to their definition records (we are avoiding emitting references
             // to things that have a definition within the same blob to save space).
 
-            Cts.MetadataType containingType = entity.ContainingType;
+            Cts.MetadataType containingType = (Cts.MetadataType)entity.ContainingType;
             MetadataRecord parentRecord = HandleType(containingType);
             TypeReference parentReferenceRecord = parentRecord as TypeReference;
             
@@ -218,14 +218,15 @@ namespace ILCompiler.Metadata
         {
             Debug.Assert(entity.IsTypeDefinition);
 
-            if (entity.ContainingType != null)
+            Cts.MetadataType containingType = (Cts.MetadataType)entity.ContainingType;
+            if (containingType != null)
             {
-                var enclosingType = (TypeDefinition)HandleType(entity.ContainingType);
+                var enclosingType = (TypeDefinition)HandleType(containingType);
                 record.EnclosingType = enclosingType;
                 enclosingType.NestedTypes.Add(record);
 
                 var namespaceDefinition =
-                    HandleNamespaceDefinition(_policy.GetModuleOfType(entity.ContainingType), entity.ContainingType.Namespace);
+                    HandleNamespaceDefinition(_policy.GetModuleOfType(containingType), entity.ContainingType.Namespace);
                 record.NamespaceDefinition = namespaceDefinition;
             }
             else