From fdbd25967ba934b951511e377fed6aa06bcbeb30 Mon Sep 17 00:00:00 2001
From: Tim Ledbetter <tim.ledbetter@ladybird.org>
Date: Tue, 2 Sep 2025 07:23:26 +0100
Subject: [PATCH] LibIDL: Allow `iterable<T>` to be defined before property
 getter

Previously, an error would occur if an `iterable<T>` was defined before
the required value iterator. An is now also reported if an`iterable<T>`
is defined before a pair iterator, previously this error would only be
reported if the iterable was defined after the pair iterator.
---
 Libraries/LibIDL/IDLParser.cpp | 18 ++++++++++++------
 Libraries/LibIDL/Types.h       |  2 ++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/Libraries/LibIDL/IDLParser.cpp b/Libraries/LibIDL/IDLParser.cpp
index 0b8af808210..4e854a9e131 100644
--- a/Libraries/LibIDL/IDLParser.cpp
+++ b/Libraries/LibIDL/IDLParser.cpp
@@ -518,18 +518,14 @@ void Parser::parse_iterable(Interface& interface)
     assert_specific('<');
     auto first_type = parse_type();
     if (lexer.next_is(',')) {
-        if (interface.supports_indexed_properties())
-            report_parsing_error("Interfaces with a pair iterator must not support indexed properties."sv, filename, input, lexer.tell());
-
         assert_specific(',');
         consume_whitespace();
         auto second_type = parse_type();
         interface.pair_iterator_types = Tuple { move(first_type), move(second_type) };
+        interface.pair_iterator_offset = lexer.tell();
     } else {
-        if (!interface.supports_indexed_properties())
-            report_parsing_error("Interfaces with a value iterator must support indexed properties."sv, filename, input, lexer.tell());
-
         interface.value_iterator_type = move(first_type);
+        interface.value_iterator_offset = lexer.tell();
     }
 
     if (interface.async_value_iterator_type.has_value())
@@ -806,6 +802,16 @@ void Parser::parse_interface(Interface& interface)
     else
         interface.implemented_name = interface.name;
 
+    if (interface.pair_iterator_types.has_value() && interface.indexed_property_getter.has_value()) {
+        VERIFY(interface.pair_iterator_offset.has_value());
+        report_parsing_error("Interfaces with a pair iterator must not support indexed properties."sv, filename, input, *interface.pair_iterator_offset);
+    }
+
+    if (interface.value_iterator_type.has_value() && !interface.supports_indexed_properties()) {
+        VERIFY(interface.value_iterator_offset.has_value());
+        report_parsing_error("Interfaces with a value iterator must support indexed properties."sv, filename, input, *interface.value_iterator_offset);
+    }
+
     interface.constructor_class = ByteString::formatted("{}Constructor", interface.implemented_name);
     interface.prototype_class = ByteString::formatted("{}Prototype", interface.implemented_name);
     interface.prototype_base_class = ByteString::formatted("{}Prototype", interface.parent_name.is_empty() ? "Object" : interface.parent_name);
diff --git a/Libraries/LibIDL/Types.h b/Libraries/LibIDL/Types.h
index 20dbf71c626..bd3ca7304cf 100644
--- a/Libraries/LibIDL/Types.h
+++ b/Libraries/LibIDL/Types.h
@@ -287,7 +287,9 @@ public:
     bool has_unscopable_member { false };
 
     Optional<NonnullRefPtr<Type const>> value_iterator_type;
+    Optional<size_t> value_iterator_offset;
     Optional<Tuple<NonnullRefPtr<Type const>, NonnullRefPtr<Type const>>> pair_iterator_types;
+    Optional<size_t> pair_iterator_offset;
 
     Optional<NonnullRefPtr<Type const>> async_value_iterator_type;
     Vector<Parameter> async_value_iterator_parameters;