Handle null == null, null != null (#30)

* Handle `null == null`, `null != null` Handle `null == null`, `null != null`. Co-authored-by: Merlin <36685500+MerlinVR@users.noreply.github.com>
vrchat-community · Dec 1, 2022 · a89fc5e · a89fc5e
1 parent baaa203
commit a89fc5e
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Showing 2 changed files with 35 additions and 3 deletions.
diff --git a/Packages/com.vrchat.UdonSharp/Editor/Compiler/Binder/BinderSyntaxVisitor.cs b/Packages/com.vrchat.UdonSharp/Editor/Compiler/Binder/BinderSyntaxVisitor.cs
@@ -674,6 +674,26 @@ private BoundExpression HandleNullCoalescingExpression(BinaryExpressionSyntax no
 
             return new BoundCoalesceExpression(node, lhs, rhs);
         }
+
+        private BoundExpression HandleNullEqualsExpression(BinaryExpressionSyntax node)
+        {
+            TypeSymbol booleanType = Context.GetTypeSymbol(SpecialType.System_Boolean);
+            IConstantValue booleanValue;
+
+            switch (node.Kind())
+            {
+                case SyntaxKind.EqualsExpression:
+                    booleanValue = new ConstantValue<bool>(true);
+                    break;
+                case SyntaxKind.NotEqualsExpression:
+                    booleanValue = new ConstantValue<bool>(false);
+                    break;
+                default:
+                    throw new InvalidOperationException("Invalid equals expression");
+            }
+
+            return new BoundConstantExpression(booleanValue, booleanType, node);
+        }
 
         public override BoundNode VisitBinaryExpression(BinaryExpressionSyntax node)
         {
@@ -683,9 +703,14 @@ public override BoundNode VisitBinaryExpression(BinaryExpressionSyntax node)
 
             if (node.Kind() == SyntaxKind.CoalesceExpression)
                 return HandleNullCoalescingExpression(node);
-            
+
             MethodSymbol binaryMethodSymbol = (MethodSymbol)GetSymbol(node);
-
+
+            if (binaryMethodSymbol == null &&
+                (node.Kind() == SyntaxKind.EqualsExpression ||
+                 node.Kind() == SyntaxKind.NotEqualsExpression))
+                return HandleNullEqualsExpression(node);
+
             BoundExpression lhs = VisitExpression(node.Left, binaryMethodSymbol.Parameters[0].Type);
             BoundExpression rhs = VisitExpression(node.Right, binaryMethodSymbol.Parameters[1].Type);
 

diff --git a/Packages/com.vrchat.UdonSharp/Tests~/TestScripts/Core/ArithmeticTest.cs b/Packages/com.vrchat.UdonSharp/Tests~/TestScripts/Core/ArithmeticTest.cs
@@ -32,6 +32,7 @@ public void ExecuteTests()
             DecimalOps();
             BitwiseNot();
             UdonBehaviourFieldCompoundAssignment();
+            NullEquals();
             CastCharToFloat();
         }
 
@@ -459,7 +460,13 @@ void UdonBehaviourFieldCompoundAssignment()
 
             tester.TestAssertion("Field struct compound assignment", _testVec.x == 4);
         }
-
+
+        void NullEquals()
+        {
+            tester.TestAssertion("Null equals null", null == null);
+            tester.TestAssertion("Null doesn't equal null", !(null != null));
+        }
+
         void CastCharToFloat()
         {
             float af = 97.5f;