Test262: fromCodePoint surrogates (#108), call arg-order (#106), Object.create proto + isPrototypeOf (#104)

Compilation/ExpressionEmitterBase.CallHelpers.cs

@@ -380,6 +380,16 @@ private void EmitDynamicMethodCallPreservingThis(Expr obj, string methodName, Li
 
     private void EmitGetPropertyAndInvoke(LocalBuilder objLocal, string methodName, List<Expr> arguments, LocalBuilder[]? argLocals = null)
     {
+        // ECMA-262 §13.3.2.1: evaluating the member-access callee `recv.method`
+        // performs RequireObjectCoercible(recv), so an undefined receiver throws
+        // TypeError *before* ArgumentListEvaluation (§13.3.6.1 step 2 runs before
+        // the callability check in steps 3/4). $Runtime.GetProperty returns
+        // undefined for a nullish base (so optional chains can short-circuit),
+        // which would otherwise defer the throw past the arguments and run their
+        // side effects. Enforce coercibility here, on the non-optional method-call
+        // path. (test262 language/expressions/call/11.2.3-3_3)
+        EmitThrowIfReceiverUndefined(objLocal, methodName);
+
         // Resolve the method first (property lookup precedes argument evaluation, per spec) and
         // store it, so the receiver and resolved fn aren't left on the IL stack while arguments are
         // evaluated — a later argument can suspend (await/yield), which requires a clear stack.
@@ -400,6 +410,35 @@ private void EmitGetPropertyAndInvoke(LocalBuilder objLocal, string methodName,
         IL.Emit(OpCodes.Call, Ctx.Runtime!.InvokeMethodValue);
     }
 
+    /// <summary>
+    /// Emits a guard that throws <c>TypeError</c> when <paramref name="objLocal"/>
+    /// holds <c>$Undefined</c> — the RequireObjectCoercible step a member-access
+    /// callee performs before its arguments are evaluated. Missing-property reads
+    /// (e.g. <c>o.bar</c> where <c>bar</c> is absent) yield <c>$Undefined</c>, so
+    /// this catches <c>o.bar.gar(sideEffect())</c> before the side effect runs.
+    ///
+    /// Deliberately does NOT reject a bare CLR <c>null</c>: compiled sloppy-mode
+    /// <c>this</c> is represented as <c>null</c> (spec says it is globalThis, which
+    /// is coercible), so <c>this.method(sideEffect())</c> must keep evaluating its
+    /// arguments. Symbols/primitives are coercible too. A genuine <c>null.x()</c>
+    /// still throws — just deferred to InvokeMethodValue, as before this guard.
+    /// </summary>
+    protected void EmitThrowIfReceiverUndefined(LocalBuilder objLocal, string methodName)
+    {
+        var okLabel = IL.DefineLabel();
+
+        IL.Emit(OpCodes.Ldloc, objLocal);
+        IL.Emit(OpCodes.Isinst, Ctx.Runtime!.UndefinedType);
+        IL.Emit(OpCodes.Brfalse, okLabel);               // not $Undefined → ok
+
+        IL.Emit(OpCodes.Ldstr, $"Cannot read properties of undefined (reading '{methodName}')");
+        IL.Emit(OpCodes.Newobj, Ctx.Runtime!.TSTypeErrorCtor);
+        IL.Emit(OpCodes.Call, Ctx.Runtime!.CreateException);
+        IL.Emit(OpCodes.Throw);
+
+        IL.MarkLabel(okLabel);
+    }
+
     /// <summary>
     /// Builds an <c>object[]</c> of the boxed call arguments on the stack. Stack: [] -&gt; [object[]].
     /// When <paramref name="argLocals"/> is non-null each element is loaded from those pre-spilled,

Compilation/ILEmitter.Calls.MethodDispatch.cs

@@ -182,6 +182,14 @@ private void EmitMethodCall(Expr.Get methodGet, List<Expr> arguments)
         var receiverLocal = IL.DeclareLocal(_ctx.Types.Object);
         IL.Emit(OpCodes.Stloc, receiverLocal);
 
+        // ECMA-262 §13.3.2.1 / §13.3.6.1: the member-access callee `recv.method`
+        // runs RequireObjectCoercible(recv) before ArgumentListEvaluation, so an
+        // undefined receiver throws TypeError *before* the arguments' side effects
+        // fire. GetProperty/InvokeMethodValue would otherwise defer the throw until
+        // after the args are built. (test262 .../call/11.2.3-3_3)
+        if (!methodGet.Optional)
+            EmitThrowIfReceiverUndefined(receiverLocal, methodName);
+
         // Load receiver for InvokeMethodValue's first argument
         IL.Emit(OpCodes.Ldloc, receiverLocal);
 

Compilation/RuntimeEmitter.Strings.cs

@@ -1719,10 +1719,28 @@ private void EmitStringFromCodePoint(TypeBuilder typeBuilder, EmittedRuntime run
 
         il.MarkLabel(validLabel);
 
-        // result = string.Concat(result, Char.ConvertFromUtf32(codePoint))
+        // result = string.Concat(result, <UTF16-encoded codePoint>)
+        // ECMA-262 §11.1.3: char.ConvertFromUtf32 rejects lone surrogates
+        // (0xD800–0xDFFF), but fromCodePoint must emit them as single UTF-16
+        // code units. Code points <= 0xFFFF (incl. lone surrogates) become one
+        // char; supplementary code points (> 0xFFFF, never a surrogate) go
+        // through ConvertFromUtf32.
         il.Emit(OpCodes.Ldloc, resultLocal);
+        var supplementaryLabel = il.DefineLabel();
+        var segmentReadyLabel = il.DefineLabel();
+        il.Emit(OpCodes.Ldloc, codePointLocal);
+        il.Emit(OpCodes.Ldc_I4, 0xFFFF);
+        il.Emit(OpCodes.Bgt, supplementaryLabel);
+        // cp <= 0xFFFF → char.ToString((char)cp)
+        il.Emit(OpCodes.Ldloc, codePointLocal);
+        il.Emit(OpCodes.Conv_U2);
+        il.Emit(OpCodes.Call, _types.GetMethod(_types.Char, "ToString", _types.Char));
+        il.Emit(OpCodes.Br, segmentReadyLabel);
+        // cp > 0xFFFF → char.ConvertFromUtf32(cp)
+        il.MarkLabel(supplementaryLabel);
         il.Emit(OpCodes.Ldloc, codePointLocal);
         il.Emit(OpCodes.Call, _types.GetMethod(_types.Char, "ConvertFromUtf32", _types.Int32));
+        il.MarkLabel(segmentReadyLabel);
         il.Emit(OpCodes.Call, _types.GetMethod(_types.String, "Concat", _types.String, _types.String));
         il.Emit(OpCodes.Stloc, resultLocal);
 

Runtime/BuiltIns/ObjectBuiltIns.cs

@@ -1438,6 +1438,17 @@ private static List<string> GetPropertyNamesFromList(System.Collections.IList li
         var proto = args[0];
         var propertiesObject = args.Count > 1 ? args[1] : null;
 
+        // ECMA-262 §20.1.2.2 step 1: if Type(O) is neither Object nor Null,
+        // throw TypeError. Object.create(undefined/number/string/bool/symbol/…)
+        // throws; only a real object or null is a valid prototype. (Mirrors the
+        // compiled-mode $Runtime.ObjectCreate guard.) Thrown as a real
+        // SharpTSTypeError so guest `assert.throws(TypeError, …)` / `instanceof`
+        // see a TypeError instance, not a bare string.
+        if (proto is SharpTSUndefined or double or int or long or bool or string
+            or System.Numerics.BigInteger or SharpTSSymbol)
+            throw new Runtime.Exceptions.ThrowException(
+                new SharpTSTypeError("Object prototype may only be an Object or null"));
+
         // ECMA-262 §20.1.2.2 step 2: Let obj be OrdinaryObjectCreate(O).
         // OrdinaryObjectCreate creates a FRESH object whose [[Prototype]] is
         // O — it does NOT copy O's own properties. Inherited properties are
@@ -1451,8 +1462,9 @@ private static List<string> GetPropertyNamesFromList(System.Collections.IList li
         result.Prototype = proto;
         // Object.create(null) → a null-prototype object that inherits nothing
         // (not even Object.prototype's methods). Distinguishes it from an
-        // ordinary object, whose Prototype is also null by default.
-        if (proto is null or SharpTSUndefined)
+        // ordinary object, whose Prototype is also null by default. (undefined
+        // is rejected by the Object-or-Null guard above, so only null reaches here.)
+        if (proto is null)
             result.IsNullPrototype = true;
 
         // If propertiesObject is provided, define properties using defineProperty semantics

Runtime/BuiltIns/StringBuiltIns.cs

@@ -242,14 +242,37 @@ private static RuntimeValue FromCodePointV2(Interpreter _, RuntimeValue receiver
         var sb = new StringBuilder();
         foreach (var arg in args)
         {
-            var codePoint = (int)arg.AsNumber();
-            if (codePoint < 0 || codePoint > 0x10FFFF)
-                throw new Exception($"RangeError: Invalid code point {codePoint}");
-            sb.Append(char.ConvertFromUtf32(codePoint));
+            // ECMA-262 §22.1.2.2: each code point must be an integral Number in
+            // [0, 0x10FFFF]; NaN / Infinity / fractional values throw RangeError.
+            var num = arg.AsNumber();
+            if (!double.IsInteger(num) || num < 0 || num > 0x10FFFF)
+                throw new Exception($"RangeError: Invalid code point {num}");
+            AppendCodePoint(sb, (int)num);
         }
         return RuntimeValue.FromString(sb.ToString());
     }
 
+    /// <summary>
+    /// ECMA-262 §11.1.3 UTF16EncodeCodePoint. Unlike <see cref="char.ConvertFromUtf32"/>,
+    /// this accepts lone surrogates (0xD800–0xDFFF): JS strings are sequences of
+    /// UTF-16 code units, so <c>String.fromCodePoint(0xDC00)</c> yields a one-unit
+    /// string holding that surrogate. .NET strings are likewise UTF-16, so a lone
+    /// surrogate is representable as a single <see cref="char"/>.
+    /// </summary>
+    internal static void AppendCodePoint(StringBuilder sb, int cp)
+    {
+        if (cp <= 0xFFFF)
+        {
+            sb.Append((char)cp);
+        }
+        else
+        {
+            cp -= 0x10000;
+            sb.Append((char)((cp >> 10) + 0xD800));
+            sb.Append((char)((cp & 0x3FF) + 0xDC00));
+        }
+    }
+
     #region V2 Implementations (RuntimeValue — no boxing)
 
     private static RuntimeValue CharAtV2(Interpreter _, string str, ReadOnlySpan<RuntimeValue> args)

Runtime/Types/SharpTSObjectPrototype.cs

@@ -144,7 +144,28 @@ private SharpTSObjectUnboundMethod(string name, Func<object?, List<object?>, obj
 
     private static object? ValueOfImpl(object? target, List<object?> args) => target;
 
-    private static object? IsPrototypeOfImpl(object? target, List<object?> args) => false;
+    private static object? IsPrototypeOfImpl(object? target, List<object?> args)
+    {
+        // ECMA-262 §20.1.3.4 Object.prototype.isPrototypeOf(V): walk V's
+        // prototype chain and return true if `this` (target) appears in it.
+        // (Was stubbed to always return false.)
+        if (args.Count == 0) return false;
+        var v = args[0];
+        // Step 1: if Type(V) is not Object, return false — primitives have no chain.
+        if (v is null or SharpTSUndefined or double or int or long or bool or string
+            or System.Numerics.BigInteger or SharpTSSymbol)
+            return false;
+
+        while (true)
+        {
+            object? proto;
+            try { proto = ObjectBuiltIns.RuntimeGetPrototypeOf(v); }
+            catch { return false; }
+            if (proto is null or SharpTSUndefined) return false;
+            if (ReferenceEquals(proto, target)) return true;
+            v = proto;
+        }
+    }
 
     private static object? PropertyIsEnumerableImpl(object? target, List<object?> args)
     {

SharpTS.Test262/baselines/compiled.txt

@@ -8115,17 +8115,17 @@ test/built-ins/RegExp/15.10.4.1-1.js Pass
 test/built-ins/RegExp/15.10.4.1-2.js Pass
 test/built-ins/RegExp/15.10.4.1-3.js Pass
 test/built-ins/RegExp/15.10.4.1-4.js Pass
-test/built-ins/RegExp/CharacterClassEscapes/character-class-digit-class-escape-negative-cases.js RuntimeError
+test/built-ins/RegExp/CharacterClassEscapes/character-class-digit-class-escape-negative-cases.js Pass
 test/built-ins/RegExp/CharacterClassEscapes/character-class-digit-class-escape-positive-cases.js Pass
 test/built-ins/RegExp/CharacterClassEscapes/character-class-non-digit-class-escape-negative-cases.js Pass
-test/built-ins/RegExp/CharacterClassEscapes/character-class-non-digit-class-escape-positive-cases.js RuntimeError
+test/built-ins/RegExp/CharacterClassEscapes/character-class-non-digit-class-escape-positive-cases.js Pass
 test/built-ins/RegExp/CharacterClassEscapes/character-class-non-whitespace-class-escape-negative-cases.js Fail
-test/built-ins/RegExp/CharacterClassEscapes/character-class-non-whitespace-class-escape-positive-cases.js RuntimeError
+test/built-ins/RegExp/CharacterClassEscapes/character-class-non-whitespace-class-escape-positive-cases.js Pass
 test/built-ins/RegExp/CharacterClassEscapes/character-class-non-word-class-escape-negative-cases.js Pass
-test/built-ins/RegExp/CharacterClassEscapes/character-class-non-word-class-escape-positive-cases.js RuntimeError
-test/built-ins/RegExp/CharacterClassEscapes/character-class-whitespace-class-escape-negative-cases.js RuntimeError
+test/built-ins/RegExp/CharacterClassEscapes/character-class-non-word-class-escape-positive-cases.js Fail
+test/built-ins/RegExp/CharacterClassEscapes/character-class-whitespace-class-escape-negative-cases.js Pass
 test/built-ins/RegExp/CharacterClassEscapes/character-class-whitespace-class-escape-positive-cases.js Fail
-test/built-ins/RegExp/CharacterClassEscapes/character-class-word-class-escape-negative-cases.js RuntimeError
+test/built-ins/RegExp/CharacterClassEscapes/character-class-word-class-escape-negative-cases.js Fail
 test/built-ins/RegExp/CharacterClassEscapes/character-class-word-class-escape-positive-cases.js Pass
 test/built-ins/RegExp/S15.10.1_A1_T1.js Pass
 test/built-ins/RegExp/S15.10.1_A1_T10.js Pass
@@ -11211,14 +11211,14 @@ test/built-ins/String/raw/template-substitutions-are-appended-on-same-index.js P
 test/built-ins/String/raw/zero-literal-segments.js Pass
 test/built-ins/String/symbol-string-coercion.js RuntimeError
 test/built-ins/String/symbol-wrapping.js Pass
-test/language/expressions/call/11.2.3-3_1.js Fail
-test/language/expressions/call/11.2.3-3_2.js Fail
-test/language/expressions/call/11.2.3-3_3.js Fail
-test/language/expressions/call/11.2.3-3_4.js Fail
+test/language/expressions/call/11.2.3-3_1.js Pass
+test/language/expressions/call/11.2.3-3_2.js Pass
+test/language/expressions/call/11.2.3-3_3.js Pass
+test/language/expressions/call/11.2.3-3_4.js Pass
 test/language/expressions/call/11.2.3-3_5.js Fail
-test/language/expressions/call/11.2.3-3_6.js Fail
-test/language/expressions/call/11.2.3-3_7.js Fail
-test/language/expressions/call/11.2.3-3_8.js Fail
+test/language/expressions/call/11.2.3-3_6.js Pass
+test/language/expressions/call/11.2.3-3_7.js Pass
+test/language/expressions/call/11.2.3-3_8.js Pass
 test/language/expressions/call/S11.2.3_A1.js Pass
 test/language/expressions/call/S11.2.3_A2.js Pass
 test/language/expressions/call/S11.2.3_A3_T1.js Fail