From 8feef376280dadcbf6de9cb5f2f43693112d46f4 Mon Sep 17 00:00:00 2001
From: Raymond Chen <oldnewthing@users.noreply.github.com>
Date: Thu, 24 Jun 2021 11:41:33 -0700
Subject: [PATCH] IReference operators in level-1 header should be forward
 declarations

Implementation relies on methods in the top-level header,
so defer implementation to there.

This reverts the change to base_reference_produce.h from #906
and reduces base_reference_produce_1.h to merely forward references.
This is enough to get structures to compile, although you cannot
meaningfully use any IReferences in them until you include
Windows.Foundation.h (which is consistent with existing rules for namespace
headers).
---
 strings/base_reference_produce.h              | 28 +++++++++++++++++++
 strings/base_reference_produce_1.h            | 20 ++-----------
 .../test_component_no_pch.idl                 |  7 +++++
 3 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/strings/base_reference_produce.h b/strings/base_reference_produce.h
index 1965efc7a..8228cbc4c 100644
--- a/strings/base_reference_produce.h
+++ b/strings/base_reference_produce.h
@@ -397,7 +397,35 @@ namespace winrt::impl
         static auto make(array_view<Windows::Foundation::Rect const> const& value) { return Windows::Foundation::PropertyValue::CreateRectArray(value); }
         using itf = Windows::Foundation::IReferenceArray<Windows::Foundation::Rect>;
     };
+}
+
+WINRT_EXPORT namespace winrt::Windows::Foundation
+{
+    template <typename T>
+    bool operator==(IReference<T> const& left, IReference<T> const& right)
+    {
+        if (get_abi(left) == get_abi(right))
+        {
+            return true;
+        }
+
+        if (!left || !right)
+        {
+            return false;
+        }
 
+        return left.Value() == right.Value();
+    }
+
+    template <typename T>
+    bool operator!=(IReference<T> const& left, IReference<T> const& right)
+    {
+        return !(left == right);
+    }
+}
+
+namespace winrt::impl
+{
     template <typename T, typename From>
     T unbox_value_type(From&& value)
     {
diff --git a/strings/base_reference_produce_1.h b/strings/base_reference_produce_1.h
index 7c5143821..0eb9b4b70 100644
--- a/strings/base_reference_produce_1.h
+++ b/strings/base_reference_produce_1.h
@@ -2,24 +2,8 @@
 WINRT_EXPORT namespace winrt::Windows::Foundation
 {
     template <typename T>
-    bool operator==(IReference<T> const& left, IReference<T> const& right)
-    {
-        if (get_abi(left) == get_abi(right))
-        {
-            return true;
-        }
-
-        if (!left || !right)
-        {
-            return false;
-        }
-
-        return left.Value() == right.Value();
-    }
+    bool operator==(IReference<T> const& left, IReference<T> const& right);
 
     template <typename T>
-    bool operator!=(IReference<T> const& left, IReference<T> const& right)
-    {
-        return !(left == right);
-    }
+    bool operator!=(IReference<T> const& left, IReference<T> const& right);
 }
diff --git a/test/test_component_no_pch/test_component_no_pch.idl b/test/test_component_no_pch/test_component_no_pch.idl
index 11e5cbebc..b576313c8 100644
--- a/test/test_component_no_pch/test_component_no_pch.idl
+++ b/test/test_component_no_pch/test_component_no_pch.idl
@@ -33,4 +33,11 @@ namespace test_component_no_pch
             Int32 Second;
         };
     }
+
+    // This structure verifies that the structure can at least be declared
+    // (but perhaps not meaningfully consumed) without having first included Windows.Foundation.h.
+    struct StructWithReference
+    {
+        Windows.Foundation.IReference<Int32> OptionalValue;
+    };
 }