From f0c2ef361a0354e0c0a34117a99985cef1ba7804 Mon Sep 17 00:00:00 2001
From: Leonard Hecker <lhecker@microsoft.com>
Date: Mon, 14 Mar 2022 16:04:18 +0100
Subject: [PATCH] Fix broken TestHostApp build (#12676)

This regressed recently in cfaa315.
Initially I tried to migrate TestHostApp to C++/WinRT, but due to the
unbearable compile times I've reverted it back to C++/CX (>20x difference).
Unfortunately I then forgot to fix the underlying issue before submitting a PR.

## PR Checklist
* [x] Closes #12673
* [x] I work here
* [x] Tests added/passed
---
 .../LocalTests_TerminalApp/TestHostApp/TestHostApp.vcxproj     | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/cascadia/LocalTests_TerminalApp/TestHostApp/TestHostApp.vcxproj b/src/cascadia/LocalTests_TerminalApp/TestHostApp/TestHostApp.vcxproj
index a97fe8064b4..896547f5ffd 100644
--- a/src/cascadia/LocalTests_TerminalApp/TestHostApp/TestHostApp.vcxproj
+++ b/src/cascadia/LocalTests_TerminalApp/TestHostApp/TestHostApp.vcxproj
@@ -51,7 +51,8 @@
 
   <ItemDefinitionGroup>
     <ClCompile>
-      <!-- Disable two-phase name lookup for C++/CLI & C++/CX code. -->
+      <!-- Disable C++20 and two-phase name lookup for C++/CLI & C++/CX code. -->
+      <LanguageStandard>stdcpp17</LanguageStandard>
       <AdditionalOptions>%(AdditionalOptions) /Zc:twoPhase-</AdditionalOptions>
       <DisableSpecificWarnings>4453;%(DisableSpecificWarnings)</DisableSpecificWarnings>
       <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(IntermediateOutputPath)</AdditionalIncludeDirectories>