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Fixed nested empty array initializers not matching their type #6

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Merged
periapsises merged 3 commits into from
Aug 27, 2026
Merged

Fixed nested empty array initializers not matching their type #6

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5a6f661
Fix nested array types not matching their empty equivalent
periapsises Aug 27, 2026
b684875
Fix nested arrays being covariant
periapsises Aug 27, 2026
9b87ebc
Add more tests for nested arrays
periapsises Aug 27, 2026
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11 changes: 10 additions & 1 deletion Crater/SemanticAnalysis/Types/ArrayType.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,16 @@ public override bool CanHold(Type other)
if (other is EmptyArrayType)
return true;

return IsSameType(other);
if (other is not ArrayType otherArray)
return false;

if (otherArray.ElementType is EmptyArrayType)
return true;

if (ElementType is ArrayType selfElement && otherArray.ElementType is ArrayType otherElement)
return selfElement.CanHold(otherElement);

return ElementType.IsSameType(otherArray.ElementType);
}

public override bool IsSameType(Type other)
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37 changes: 37 additions & 0 deletions Tests/ArrayTypeTests.cs
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Expand Up @@ -58,4 +58,41 @@ public void CanIndexRecursiveArrays()
Assert.That(innerResult, Is.Not.Null);
Assert.That(innerResult.IsSameType(new NullableType(TypeRegistry.NumberType)));
}

[Test]
public void CanHoldNestedEmptyArray()
{
var numberArray = new ArrayType(TypeRegistry.NumberType, TypeRegistry.AnyType);
var nestedNumberArray = new ArrayType(numberArray, TypeRegistry.AnyType);
var nestedEmptyArray = new ArrayType(new EmptyArrayType(), TypeRegistry.AnyType);

Assert.That(nestedNumberArray.CanHold(nestedEmptyArray));
}

[Test]
public void CanHoldDeeplyNestedEmptyArray()
{
var numberArray = new ArrayType(TypeRegistry.NumberType, TypeRegistry.AnyType);
var nestedNumberArray = new ArrayType(numberArray, TypeRegistry.AnyType);
var deeplyNestedNumberArray = new ArrayType(nestedNumberArray, TypeRegistry.AnyType);

var emptyArray = new EmptyArrayType();
var nestedEmptyArray = new ArrayType(emptyArray, TypeRegistry.AnyType);
var deeplyNestedEmptyArray = new ArrayType(nestedEmptyArray, TypeRegistry.AnyType);

Assert.That(deeplyNestedNumberArray.CanHold(deeplyNestedEmptyArray));
}

[Test]
public void EmptyNestedArrayCannotHoldConcreteNestedArray()
{
var emptyArray = new EmptyArrayType();
var nestedEmptyArray = new ArrayType(emptyArray, TypeRegistry.AnyType);
var emptyNestedArray = new ArrayType(nestedEmptyArray, TypeRegistry.AnyType);

var numberArray = new ArrayType(TypeRegistry.NumberType, TypeRegistry.AnyType);
var nestedNumberArray = new ArrayType(numberArray, TypeRegistry.AnyType);

Assert.That(!emptyNestedArray.CanHold(nestedNumberArray));
}
}
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