1 files changed, 10 insertions, 1 deletions
diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index 7a0dcb06f..f8a80c09b 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -10405,7 +10405,16 @@ void SemanticsDeclHeaderVisitor::visitAbstractStorageDeclCommon(ContainerDecl* d
 
 void SemanticsDeclHeaderVisitor::visitSubscriptDecl(SubscriptDecl* decl)
 {
-    decl->returnType = CheckUsableType(decl->returnType, decl);
+    // __subscript needs to have a return type specified. Check if return type
+    // is missing (represented as IncompleteExpr) and return an error.
+    if (decl->returnType.exp && as<IncompleteExpr>(decl->returnType.exp))
+    {
+        getSink()->diagnose(decl, Diagnostics::subscriptMustHaveReturnType);
+    }
+    else if (decl->returnType.exp)
+    {
+        decl->returnType = CheckUsableType(decl->returnType, decl);
+    }
 
     visitAbstractStorageDeclCommon(decl);