From abcdc75e008aa87dc733f29a9ec75e6508923ba5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jaigan=C3=A9sh=20Kumaran?= <jaiganesh.kumaran@outlook.com>
Date: Mon, 20 Feb 2023 21:08:23 +0530
Subject: [PATCH] Add `to_hstring` overload for `IStringable` (#1271)

---
 cppwinrt/code_writers.h                 |  1 +
 cppwinrt/cppwinrt.vcxproj               |  1 +
 cppwinrt/cppwinrt.vcxproj.filters       |  5 ++++-
 strings/base_stringable_to_hstring.h    |  8 ++++++++
 test/old_tests/UnitTests/to_hstring.cpp | 12 ++++++++++++
 5 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 strings/base_stringable_to_hstring.h

diff --git a/cppwinrt/code_writers.h b/cppwinrt/code_writers.h
index c986c927f..e0162fe45 100644
--- a/cppwinrt/code_writers.h
+++ b/cppwinrt/code_writers.h
@@ -3253,6 +3253,7 @@ struct WINRT_IMPL_EMPTY_BASES produce_dispatch_to_overridable<T, D, %>
             w.write(strings::base_reference_produce);
             w.write(strings::base_deferral);
             w.write(strings::base_coroutine_foundation);
+            w.write(strings::base_stringable_to_hstring);
             w.write(strings::base_stringable_format);
             w.write(strings::base_stringable_streams);
         }
diff --git a/cppwinrt/cppwinrt.vcxproj b/cppwinrt/cppwinrt.vcxproj
index 75d8cee1e..f0d1e5706 100644
--- a/cppwinrt/cppwinrt.vcxproj
+++ b/cppwinrt/cppwinrt.vcxproj
@@ -81,6 +81,7 @@
     <ClInclude Include="..\strings\base_string.h" />
     <ClInclude Include="..\strings\base_stringable_format.h" />
     <ClInclude Include="..\strings\base_stringable_streams.h" />
+    <ClInclude Include="..\strings\base_stringable_to_hstring.h" />
     <ClInclude Include="..\strings\base_string_input.h" />
     <ClInclude Include="..\strings\base_string_operators.h" />
     <ClInclude Include="..\strings\base_stringable_format_1.h" />
diff --git a/cppwinrt/cppwinrt.vcxproj.filters b/cppwinrt/cppwinrt.vcxproj.filters
index 01aecb75e..96129ab20 100644
--- a/cppwinrt/cppwinrt.vcxproj.filters
+++ b/cppwinrt/cppwinrt.vcxproj.filters
@@ -169,7 +169,7 @@
     <ClInclude Include="..\strings\base_stringable_format.h">
       <Filter>strings</Filter>
     </ClInclude>
-     <ClInclude Include="..\strings\base_stringable_streams.h">
+    <ClInclude Include="..\strings\base_stringable_streams.h">
       <Filter>strings</Filter>
     </ClInclude>
     <ClInclude Include="..\strings\base_xaml_component_connector.h">
@@ -184,6 +184,9 @@
     <ClInclude Include="..\strings\base_xaml_component_connector_winui.h">
       <Filter>strings</Filter>
     </ClInclude>
+    <ClInclude Include="..\strings\base_stringable_to_hstring.h">
+      <Filter>strings</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="$(OutDir)version.rc" />
diff --git a/strings/base_stringable_to_hstring.h b/strings/base_stringable_to_hstring.h
new file mode 100644
index 000000000..f92da965b
--- /dev/null
+++ b/strings/base_stringable_to_hstring.h
@@ -0,0 +1,8 @@
+
+WINRT_EXPORT namespace winrt
+{
+    inline hstring to_hstring(Windows::Foundation::IStringable const& stringable)
+    {
+        return stringable.ToString();
+    }
+}
diff --git a/test/old_tests/UnitTests/to_hstring.cpp b/test/old_tests/UnitTests/to_hstring.cpp
index 9f3463a56..1d287c09b 100644
--- a/test/old_tests/UnitTests/to_hstring.cpp
+++ b/test/old_tests/UnitTests/to_hstring.cpp
@@ -4,6 +4,14 @@
 
 using namespace winrt;
 
+struct stringable : winrt::implements<stringable, winrt::Windows::Foundation::IStringable>
+{
+    winrt::hstring ToString()
+    {
+        return L"a stringable object";
+    }
+};
+
 namespace
 {
     void test_cases()
@@ -82,6 +90,10 @@ namespace
             hstring const c = to_hstring(b);
             REQUIRE(a == c);
         }
+        {
+            auto const obj = make<stringable>();
+            REQUIRE(to_hstring(obj) == obj.ToString());
+        }
     }
 }