Better unreachable code elimination in CoreLib

Author: jkotas

src/libraries/Common/src/System/Reflection/Metadata/TypeNameParser.cs

@@ -51,7 +51,7 @@ private TypeNameParser(ReadOnlySpan<char> name, bool throwOnError, TypeNameParse
             {
                 if (throwOnError)
                 {
-                    if (recursiveDepth >= parser._parseOptions.MaxNodes)
+                    if (parser._parseOptions.IsMaxDepthExceeded(recursiveDepth))
                     {
                         ThrowInvalidOperation_MaxNodesExceeded(parser._parseOptions.MaxNodes);
                     }
@@ -250,7 +250,7 @@ private bool TryParseAssemblyName(ref AssemblyNameInfo? assemblyName)
 
         private bool TryDive(ref int depth)
         {
-            if (depth >= _parseOptions.MaxNodes)
+            if (_parseOptions.IsMaxDepthExceeded(depth))
             {
                 return false;
             }

src/libraries/Common/src/System/Reflection/Metadata/TypeNameParserOptions.cs

@@ -27,5 +27,7 @@ public int MaxNodes
                 _maxNodes = value;
             }
         }
+
+        internal bool IsMaxDepthExceeded(int depth) => depth >= _maxNodes
     }
 }

src/libraries/Common/src/System/Reflection/TypeNameParser.Helpers.cs

@@ -15,7 +15,16 @@ internal struct TypeNameParseOptions
     {
         public TypeNameParseOptions() { }
 #pragma warning disable CA1822 // Mark members as static
-        public int MaxNodes => int.MaxValue; // CoreLib does not enforce any limits
+        // CoreLib does not enforce any limits
+        public bool IsMaxDepthExceeded(int _) => false;
+        public int MaxNodes
+        {
+            get
+            {
+                 Debug.Fail("Expected to be unreachable");
+                 return 0;
+            }
+        }
 #pragma warning restore CA1822
     }
 }