[vm] Harden access to unchecked natives.

Bug: #37234
Change-Id: I567b3fa177e89db50345e174a07c98b10c53f102
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105721
Commit-Queue: Ryan Macnak <[email protected]>
Reviewed-by: Régis Crelier <[email protected]>
Reviewed-by: Siva Annamalai <[email protected]>

Author: rmacnak-google

runtime/lib/function.dart

@@ -6,6 +6,10 @@
 
 @pragma("vm:entry-point")
 class _Closure implements Function {
+  factory _Closure._uninstantiable() {
+    throw "Unreachable";
+  }
+
   bool operator ==(Object other) native "Closure_equals";
 
   int get hashCode {

runtime/lib/integers.dart

@@ -480,8 +480,9 @@ abstract class _IntegerImplementation implements int {
 @pragma("vm:entry-point")
 class _Smi extends _IntegerImplementation {
   factory _Smi._uninstantiable() {
-    throw new UnsupportedError("_Smi can only be allocated by the VM");
+    throw "Unreachable";
   }
+
   int get hashCode => this;
   int get _identityHashCode => this;
   @pragma("vm:exact-result-type", "dart:core#_Smi")
@@ -682,8 +683,9 @@ class _Smi extends _IntegerImplementation {
 @pragma("vm:entry-point")
 class _Mint extends _IntegerImplementation {
   factory _Mint._uninstantiable() {
-    throw new UnsupportedError("_Mint can only be allocated by the VM");
+    throw "Unreachable";
   }
+
   int get hashCode => this;
   int get _identityHashCode => this;
   @pragma("vm:non-nullable-result-type")

runtime/lib/lib_prefix.dart

@@ -7,6 +7,10 @@
 // This type corresponds to the VM-internal class LibraryPrefix.
 @pragma("vm:entry-point")
 class _LibraryPrefix {
+  factory _LibraryPrefix._uninstantiable() {
+    throw "Unreachable";
+  }
+
   bool _load() native "LibraryPrefix_load";
   Object _loadError() native "LibraryPrefix_loadError";
   bool isLoaded() native "LibraryPrefix_isLoaded";

runtime/lib/mirror_reference.dart

@@ -7,7 +7,7 @@
 @pragma("vm:entry-point")
 class _MirrorReference {
   factory _MirrorReference._uninstantiable() {
-    throw new UnsupportedError("class _MirrorReference cannot be instantiated");
+    throw "Unreachable";
   }
 
   bool operator ==(other) native "MirrorReference_equals";

runtime/lib/regexp_patch.dart

@@ -148,7 +148,7 @@ class _RegExpHashValue {
 }
 
 class _RegExpMatch implements RegExpMatch {
-  _RegExpMatch(this._regexp, this.input, this._match);
+  _RegExpMatch._(this._regexp, this.input, this._match);
 
   int get start => _start(0);
   int get end => _end(0);
@@ -222,7 +222,7 @@ class _RegExp implements RegExp {
     if (match == null) {
       return null;
     }
-    return new _RegExpMatch(this, str, match);
+    return new _RegExpMatch._(this, str, match);
   }
 
   Iterable<RegExpMatch> allMatches(String string, [int start = 0]) {
@@ -242,7 +242,7 @@ class _RegExp implements RegExp {
     }
     List<int> list = _ExecuteMatchSticky(string, start);
     if (list == null) return null;
-    return new _RegExpMatch(this, string, list);
+    return new _RegExpMatch._(this, string, list);
   }
 
   bool hasMatch(String str) {
@@ -379,7 +379,7 @@ class _AllMatchesIterator implements Iterator<RegExpMatch> {
     if (_nextIndex <= _str.length) {
       var match = _re._ExecuteMatch(_str, _nextIndex);
       if (match != null) {
-        _current = new _RegExpMatch(_re, _str, match);
+        _current = new _RegExpMatch._(_re, _str, match);
         _nextIndex = _current.end;
         if (_nextIndex == _current.start) {
           // Zero-width match. Advance by one more, unless the regexp

runtime/lib/string_patch.dart

@@ -945,10 +945,7 @@ abstract class _StringBase implements String {
 
 @pragma("vm:entry-point")
 class _OneByteString extends _StringBase {
-  factory _OneByteString._uninstantiable() {
-    throw new UnsupportedError(
-        "_OneByteString can only be allocated by the VM");
-  }
+  factory _OneByteString._uninstantiable() { throw "Unreachable"; }
 
   @pragma("vm:exact-result-type", "dart:core#_Smi")
   int get hashCode native "String_getHashCode";
@@ -1254,10 +1251,7 @@ class _OneByteString extends _StringBase {
 
 @pragma("vm:entry-point")
 class _TwoByteString extends _StringBase {
-  factory _TwoByteString._uninstantiable() {
-    throw new UnsupportedError(
-        "_TwoByteString can only be allocated by the VM");
-  }
+  factory _TwoByteString._uninstantiable() { throw "Unreachable"; }
 
   static String _allocateFromTwoByteList(List<int> list, int start, int end)
       native "TwoByteString_allocateFromTwoByteList";
@@ -1277,10 +1271,7 @@ class _TwoByteString extends _StringBase {
 
 @pragma("vm:entry-point")
 class _ExternalOneByteString extends _StringBase {
-  factory _ExternalOneByteString._uninstantiable() {
-    throw new UnsupportedError(
-        "_ExternalOneByteString can only be allocated by the VM");
-  }
+  factory _ExternalOneByteString._uninstantiable() { throw "Unreachable"; }
 
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isOneByteWhitespace(codeUnit);
@@ -1296,10 +1287,7 @@ class _ExternalOneByteString extends _StringBase {
 
 @pragma("vm:entry-point")
 class _ExternalTwoByteString extends _StringBase {
-  factory _ExternalTwoByteString._uninstantiable() {
-    throw new UnsupportedError(
-        "_ExternalTwoByteString can only be allocated by the VM");
-  }
+  factory _ExternalTwoByteString._uninstantiable() { throw "Unreachable"; }
 
   bool _isWhitespace(int codeUnit) {
     return _StringBase._isTwoByteWhitespace(codeUnit);

runtime/lib/type_patch.dart

@@ -14,14 +14,26 @@ abstract class _AbstractType implements Type {
 // Equivalent of RawType.
 @pragma("vm:entry-point")
 class _Type extends _AbstractType {
+  factory _Type._uninstantiable() {
+    throw "Unreachable";
+  }
+
   @pragma("vm:exact-result-type", "dart:core#_Smi")
   int get hashCode native "Type_getHashCode";
 }
 
 // Equivalent of RawTypeRef.
 @pragma("vm:entry-point")
-class _TypeRef extends _AbstractType {}
+class _TypeRef extends _AbstractType {
+  factory _TypeRef._uninstantiable() {
+    throw "Unreachable";
+  }
+}
 
 // Equivalent of RawTypeParameter.
 @pragma("vm:entry-point")
-class _TypeParameter extends _AbstractType {}
+class _TypeParameter extends _AbstractType {
+  factory _TypeParameter._uninstantiable() {
+    throw "Unreachable";
+  }
+}