Check structs can have mutually recursive fields

3 files changed, 45 insertions, 1 deletions

diff --git a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
index e5b13e6c..259c3215 100644
--- a/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/typed/TypedNodeMatchers.java
@@ -281,6 +281,12 @@ public class TypedNodeMatchers {
         );
     }
 
+    public static Matcher<TypedTypeLevelExpressionNode<?>> isTypedTypeLevelExpressionNode(
+        TypeLevelValue value
+    ) {
+        return has("value", x -> x.value(), equalTo(value));
+    }
+
     public static Matcher<TypedTypeLevelExpressionNode<?>> isTypedTypeLevelReferenceNode(
         String name,
         Matcher<TypeLevelValue> value
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
index d8fdc3ee..5a081076 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerNamespaceTests.java
@@ -362,6 +362,45 @@ public class TypeCheckerNamespaceTests {
     }
 
     @Test
+    public void structsCanHaveMutuallyRecursiveFields() {
+        var namespaceName = NamespaceName.of("Example", "Project");
+        var untyped = Untyped.namespace(namespaceName, List.of(
+            UntypedStructDefinitionNode.builder()
+                .withName("A")
+                .addField(Untyped.structFieldDefinition("b", Untyped.typeLevelReference("B")))
+                .build(),
+            UntypedStructDefinitionNode.builder()
+                .withName("B")
+                .addField(Untyped.structFieldDefinition("a", Untyped.typeLevelReference("A")))
+                .build()
+        ));
+        var context = TypeCheckerContext.EMPTY;
+
+        var result = TypeChecker.typeCheckNamespace(untyped, context);
+
+        assertThat(
+            result.value(),
+            isTypedNamespaceNode()
+                .withBody(isSequence(
+                    isTypedStructDefinitionNode()
+                        .withName("A")
+                        .withFields(isSequence(
+                            isTypedStructFieldDefinitionNode()
+                                .withName("b")
+                                .withType(isTypedTypeLevelExpressionNode(Types.struct(namespaceName, "B")))
+                        )),
+                    isTypedStructDefinitionNode()
+                        .withName("B")
+                        .withFields(isSequence(
+                            isTypedStructFieldDefinitionNode()
+                                .withName("a")
+                                .withType(isTypedTypeLevelExpressionNode(Types.struct(namespaceName, "A")))
+                        ))
+                ))
+        );
+    }
+
+    @Test
     public void typesOfFieldsAreStored() {
         var namespaceName = NamespaceName.of("Example");
         var untyped = Untyped.namespace(
diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
index dc23fa1c..f8cb0fc5 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerStructDefinitionTests.java
@@ -6,7 +6,6 @@ import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.ast.untyped.UntypedStructDefinitionNode;
 import org.shedlang.compiler.types.NamespaceName;
-import org.shedlang.compiler.types.StructType;
 import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;