Undo dictionary changes

Author: kg

src/libraries/System.Private.CoreLib/src/System/AppContext.cs

@@ -152,26 +152,10 @@ internal static unsafe void Setup(char** pNames, char** pValues, int count)
             }
         }
 
-        private sealed class AppContextKeyComparer : IEqualityComparer<string?>
-        {
-            public bool Equals(string? x, string? y) => string.Equals(x, y);
-
-            public int GetHashCode(string? obj)
-            {
-                Debug.Assert(obj != null, "This implementation is only called from first-party collection types that guarantee non-null parameters.");
-                return obj.GetNonRandomizedHashCode();
-            }
-        }
-
         internal static unsafe void Setup(char** pNames, uint** pNameLengths, char** pValues, uint** pValueLengths, int count)
         {
             Debug.Assert(s_dataStore == null, "s_dataStore is not expected to be inited before Setup is called");
-            // HACK: Use a special comparer that does not pull in all the dependencies that
-            //  the default BCL string comparers pull in
-            IEqualityComparer<string?> comparer = new AppContextKeyComparer();
-            // HACK: Use a special version of the Dictionary constructor that does not pull in a
-            //  large amount of extra code in order to instantiate this dictionary
-            s_dataStore = new Dictionary<string, object?>(count, comparer, true);
+            s_dataStore = new Dictionary<string, object?>(count);
             for (int i = 0; i < count; i++)
             {
                 s_dataStore.Add(new string(pNames[i], 0, (int)pNameLengths[i]), new string(pValues[i], 0, (int)pValueLengths[i]));

src/libraries/System.Private.CoreLib/src/System/Collections/Generic/Dictionary.cs

@@ -43,9 +43,7 @@ public Dictionary(int capacity) : this(capacity, null) { }
 
         public Dictionary(IEqualityComparer<TKey>? comparer) : this(0, comparer) { }
 
-        public Dictionary(int capacity, IEqualityComparer<TKey>? comparer) : this(0, comparer, false) { }
-
-        internal Dictionary(int capacity, IEqualityComparer<TKey>? comparer, bool useProvidedComparer)
+        public Dictionary(int capacity, IEqualityComparer<TKey>? comparer)
         {
             if (capacity < 0)
             {
@@ -68,16 +66,13 @@ internal Dictionary(int capacity, IEqualityComparer<TKey>? comparer, bool usePro
             {
                 _comparer = comparer ?? EqualityComparer<TKey>.Default;
 
-                if (!useProvidedComparer)
+                // Special-case EqualityComparer<string>.Default, StringComparer.Ordinal, and StringComparer.OrdinalIgnoreCase.
+                // We use a non-randomized comparer for improved perf, falling back to a randomized comparer if the
+                // hash buckets become unbalanced.
+                if (typeof(TKey) == typeof(string) &&
+                    NonRandomizedStringEqualityComparer.GetStringComparer(_comparer!) is IEqualityComparer<string> stringComparer)
                 {
-                    // Special-case EqualityComparer<string>.Default, StringComparer.Ordinal, and StringComparer.OrdinalIgnoreCase.
-                    // We use a non-randomized comparer for improved perf, falling back to a randomized comparer if the
-                    // hash buckets become unbalanced.
-                    if (typeof(TKey) == typeof(string) &&
-                        NonRandomizedStringEqualityComparer.GetStringComparer(_comparer!) is IEqualityComparer<string> stringComparer)
-                    {
-                        _comparer = (IEqualityComparer<TKey>)stringComparer;
-                    }
+                    _comparer = (IEqualityComparer<TKey>)stringComparer;
                 }
             }
             else if (comparer is not null && // first check for null to avoid forcing default comparer instantiation unnecessarily