(interpreter) Make int == double use value-type semantics (#413)

This is an important preparation for #409, where we will use the same semantics. Doing the change already not for interpreted mode makes things easier, since we can then use the same tests for both interpreted and compiled mode.
perlang-org · Oct 22, 2023 · 8f6e529 · 8f6e529
1 parent 28f6dae
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diff --git a/release-notes/v0.4.0.md b/release-notes/v0.4.0.md
@@ -24,6 +24,7 @@
 - Remove Moq dependency [[#380][380]]
 
 ### Fixed
+- Make `int == double` use value-type semantics [[#413][413]]
 
 ### Tests
 - Minor test improvements [[#410][410]]
@@ -39,3 +40,4 @@
 [407]: https://github.com/perlang-org/perlang/pull/407
 [410]: https://github.com/perlang-org/perlang/pull/410
 [412]: https://github.com/perlang-org/perlang/pull/412
+[413]: https://github.com/perlang-org/perlang/pull/413
diff --git a/src/Perlang.Interpreter/PerlangInterpreter.cs b/src/Perlang.Interpreter/PerlangInterpreter.cs
@@ -9,6 +9,7 @@
 using System.Numerics;
 using System.Reflection;
 using System.Text;
+using Microsoft.CSharp.RuntimeBinder;
 using Perlang.Attributes;
 using Perlang.Exceptions;
 using Perlang.Internal.Extensions;
@@ -948,10 +949,23 @@ private static bool IsEqual(object? a, object? b)
 
             if (a == null)
             {
+                // null != non-null
                 return false;
             }
 
-            return a.Equals(b);
+            // Note: must use dynamic here since `object == object` behaves differently than e.g. `int == double`,
+            // tragically enough. More details:
+            // https://learn.microsoft.com/en-us/dotnet/api/System.Object.Equals?view=net-7.0#notes-for-callers
+            try
+            {
+                return (dynamic)a == (dynamic?)b;
+            }
+            catch (RuntimeBinderException)
+            {
+                // This will happen when trying to compare e.g `double == BigInteger`. We fall back to Equals() in this
+                // case, hoping that it will make sense...
+                return a.Equals(b);
+            }
         }
 
         public object? VisitGroupingExpr(Expr.Grouping expr)

diff --git a/src/Perlang.Tests.Integration/Operator/Binary/BinaryOperatorData.cs b/src/Perlang.Tests.Integration/Operator/Binary/BinaryOperatorData.cs
@@ -284,8 +284,8 @@ public static class BinaryOperatorData
         {
             new object[] { "12", "34", "True" },
             new object[] { "12", "12", "False" },
-            new object[] { "12", "12.0", "True" }, // Same value but different types. Note: this is truthy in C# AND Java.
-            new object[] { "12.0", "12", "True" }, // Same value but different types. Note: this is truthy in C# AND Java.
+            new object[] { "12", "12.0", "False" }, // Same value but different types. We follow the precedent of C#, Java and C++ and consider these to be equal.
+            new object[] { "12.0", "12", "False" }, // Likewise
 
             new object[] { "2147483647", "4294967295", "True" },
             new object[] { "2147483647", "9223372036854775807", "True" },
@@ -341,8 +341,8 @@ public static class BinaryOperatorData
         {
             new object[] { "12", "34", "False" },
             new object[] { "12", "12", "True" },
-            new object[] { "12", "12.0", "False" }, // Same value but different types. Note: this is truthy in C# AND Java.
-            new object[] { "12.0", "12", "False" }, // Same value but different types. Note: this is truthy in C# AND Java.
+            new object[] { "12", "12.0", "True" }, // Same value but different types. We follow the precedent of C#, Java and C++ and consider these to be equal.
+            new object[] { "12.0", "12", "True" }, // Likewise
             new object[] { "12.345", "12.345", "True" },
             new object[] { "12.345", "67.890", "False" },