From 8fe3ffe8c7aad4c3270b889bce0efaf4ab912157 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 16 Oct 2026 08:21:19 +0100
Subject: Check row type is struct

---
 .../hobgoblin/compiler/typechecker/TypeChecker.java    | 12 +++++++++---
 .../errors/TableRowTypeMustBeStructError.java          | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 src/main/java/org/zwobble/hobgoblin/compiler/typechecker/errors/TableRowTypeMustBeStructError.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
index eb3e09d..211726b 100644
--- a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/TypeChecker.java
@@ -468,12 +468,18 @@ public class TypeChecker {
         UntypedTableDefinitionNode untyped,
         TypeCheckerNamespaceContext context
     ) {
-        var rowType = typeCheckMetaType(untyped.rowType(), context);
+        var rowTypeTypedNode = typeCheckMetaType(untyped.rowType(), context);
+
+        if (!(rowTypeTypedNode.value() instanceof StructType rowType)) {
+            throw new TableRowTypeMustBeStructError(
+                rowTypeTypedNode.value(),
+                rowTypeTypedNode.source()
+            );
+        }
 
         return new TypedTableDefinitionNode(
             untyped.name(),
-            // TODO: handle not struct type.
-            (StructType) rowType.value(),
+            rowType,
             // TODO: check primary key is valid.
             untyped.primaryKey(),
             untyped.docComment(),
diff --git a/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/errors/TableRowTypeMustBeStructError.java b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/errors/TableRowTypeMustBeStructError.java
new file mode 100644
index 0000000..17b93d4
--- /dev/null
+++ b/src/main/java/org/zwobble/hobgoblin/compiler/typechecker/errors/TableRowTypeMustBeStructError.java
@@ -0,0 +1,18 @@
+package org.zwobble.hobgoblin.compiler.typechecker.errors;
+
+import org.zwobble.hobgoblin.compiler.errors.SourceError;
+import org.zwobble.hobgoblin.compiler.sources.Source;
+import org.zwobble.hobgoblin.compiler.types.Type;
+
+public class TableRowTypeMustBeStructError extends SourceError {
+    private final Type rowType;
+
+    public TableRowTypeMustBeStructError(Type rowType, Source source) {
+        super("row types must be structs, but was " + rowType.describe(), source);
+        this.rowType = rowType;
+    }
+
+    public Type rowType() {
+        return rowType;
+    }
+}
-- 
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