From 3aec3caf949c246855a0d655eb359935605930c4 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Thu, 13 Aug 2026 17:30:22 +0100
Subject: Make JavaTypeArg a sealed interface

---
 .../hobgoblin/compiler/output/lang/java/JavaWriter.java  | 10 +++++-----
 .../compiler/output/lang/java/ast/JavaTypeArg.java       | 16 +++++++++++-----
 .../compiler/output/lang/java/ast/JavaTypeVariance.java  |  6 ------
 3 files changed, 16 insertions(+), 16 deletions(-)
 delete mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeVariance.java

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
index 29bb762..1d14b29 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriter.java
@@ -422,15 +422,15 @@ public class JavaWriter implements AutoCloseable {
     }
 
     private static void writeTypeArg(JavaTypeArg arg, WriteString writer) throws IOException {
-        switch (arg.variance()) {
-            case INVARIANT -> {
-                // Do nothing.
+        switch (arg) {
+            case JavaTypeArg.Invariant invariant -> {
+                writeTypeRef(invariant.type(), writer);
             }
-            case SUPER -> {
+            case JavaTypeArg.SuperType superType -> {
                 writer.write("? super ");
+                writeTypeRef(superType.type(), writer);
             }
         }
-        writeTypeRef(arg.type(), writer);
     }
 
     // == Visibility ==
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeArg.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeArg.java
index 6bbee59..8253275 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeArg.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeArg.java
@@ -1,11 +1,17 @@
 package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
 
-public record JavaTypeArg(JavaTypeVariance variance, JavaTypeRef type) {
-    public static JavaTypeArg invariant(JavaTypeRef type) {
-        return new JavaTypeArg(JavaTypeVariance.INVARIANT, type);
+public sealed interface JavaTypeArg {
+    static JavaTypeArg invariant(JavaTypeRef type) {
+        return new Invariant(type);
     }
 
-    public static JavaTypeArg superType(JavaTypeRef type) {
-        return new JavaTypeArg(JavaTypeVariance.SUPER, type);
+    record Invariant(JavaTypeRef type) implements JavaTypeArg {
+    }
+
+    static JavaTypeArg superType(JavaTypeRef type) {
+        return new SuperType(type);
+    }
+
+    record SuperType(JavaTypeRef type) implements JavaTypeArg {
     }
 }
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeVariance.java b/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeVariance.java
deleted file mode 100644
index 00a671d..0000000
--- a/src/main/java/org/zwobble/hobgoblin/compiler/output/lang/java/ast/JavaTypeVariance.java
+++ /dev/null
@@ -1,6 +0,0 @@
-package org.zwobble.hobgoblin.compiler.output.lang.java.ast;
-
-public enum JavaTypeVariance {
-    INVARIANT,
-    SUPER
-}
-- 
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