Merge in 'release/5.0' changesv5.0.9

12 files changed, 315 insertions, 49 deletions

diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 8f8c16f4add..97988db5dea 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -10,61 +10,61 @@
     </Dependency>
   </ProductDependencies>
   <ToolsetDependencies>
-    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Helix.Sdk" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Helix.Sdk" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.GenAPI" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.GenAPI" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.GenFacades" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.GenFacades" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.XUnitExtensions" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.XUnitExtensions" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.XUnitConsoleRunner" Version="2.5.1-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.XUnitConsoleRunner" Version="2.5.1-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Build.Tasks.Packaging" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Build.Tasks.Packaging" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.CodeAnalysis" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.CodeAnalysis" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Build.Tasks.TargetFramework.Sdk" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Build.Tasks.TargetFramework.Sdk" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.RemoteExecutor" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.RemoteExecutor" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Build.Tasks.Feed" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Build.Tasks.Feed" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.VersionTools.Tasks" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.VersionTools.Tasks" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk" Version="5.0.0-beta.21160.3">
+    <Dependency Name="Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk" Version="5.0.0-beta.21328.3">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>670382be6a978ba401c21c57ba44311199d2682a</Sha>
+      <Sha>5266aa9856457785b84739fda2616f21da7ee6b4</Sha>
     </Dependency>
     <Dependency Name="optimization.windows_nt-x64.IBC.CoreFx" Version="99.99.99-master-20200806.6">
       <Uri>https://dev.azure.com/dnceng/internal/_git/dotnet-optimization</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index adbdaf95aa4..5aeea3f16a0 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -48,16 +48,16 @@
   </ItemGroup>
   <PropertyGroup>
     <!-- Arcade dependencies -->
-    <MicrosoftDotNetApiCompatVersion>5.0.0-beta.21160.3</MicrosoftDotNetApiCompatVersion>
-    <MicrosoftDotNetBuildTasksFeedVersion>5.0.0-beta.21160.3</MicrosoftDotNetBuildTasksFeedVersion>
-    <MicrosoftDotNetCodeAnalysisVersion>5.0.0-beta.21160.3</MicrosoftDotNetCodeAnalysisVersion>
-    <MicrosoftDotNetGenAPIVersion>5.0.0-beta.21160.3</MicrosoftDotNetGenAPIVersion>
-    <MicrosoftDotNetGenFacadesVersion>5.0.0-beta.21160.3</MicrosoftDotNetGenFacadesVersion>
-    <MicrosoftDotNetXUnitExtensionsVersion>5.0.0-beta.21160.3</MicrosoftDotNetXUnitExtensionsVersion>
-    <MicrosoftDotNetXUnitConsoleRunnerVersion>2.5.1-beta.21160.3</MicrosoftDotNetXUnitConsoleRunnerVersion>
-    <MicrosoftDotNetBuildTasksPackagingVersion>5.0.0-beta.21160.3</MicrosoftDotNetBuildTasksPackagingVersion>
-    <MicrosoftDotNetRemoteExecutorVersion>5.0.0-beta.21160.3</MicrosoftDotNetRemoteExecutorVersion>
-    <MicrosoftDotNetVersionToolsTasksVersion>5.0.0-beta.21160.3</MicrosoftDotNetVersionToolsTasksVersion>
+    <MicrosoftDotNetApiCompatVersion>5.0.0-beta.21328.3</MicrosoftDotNetApiCompatVersion>
+    <MicrosoftDotNetBuildTasksFeedVersion>5.0.0-beta.21328.3</MicrosoftDotNetBuildTasksFeedVersion>
+    <MicrosoftDotNetCodeAnalysisVersion>5.0.0-beta.21328.3</MicrosoftDotNetCodeAnalysisVersion>
+    <MicrosoftDotNetGenAPIVersion>5.0.0-beta.21328.3</MicrosoftDotNetGenAPIVersion>
+    <MicrosoftDotNetGenFacadesVersion>5.0.0-beta.21328.3</MicrosoftDotNetGenFacadesVersion>
+    <MicrosoftDotNetXUnitExtensionsVersion>5.0.0-beta.21328.3</MicrosoftDotNetXUnitExtensionsVersion>
+    <MicrosoftDotNetXUnitConsoleRunnerVersion>2.5.1-beta.21328.3</MicrosoftDotNetXUnitConsoleRunnerVersion>
+    <MicrosoftDotNetBuildTasksPackagingVersion>5.0.0-beta.21328.3</MicrosoftDotNetBuildTasksPackagingVersion>
+    <MicrosoftDotNetRemoteExecutorVersion>5.0.0-beta.21328.3</MicrosoftDotNetRemoteExecutorVersion>
+    <MicrosoftDotNetVersionToolsTasksVersion>5.0.0-beta.21328.3</MicrosoftDotNetVersionToolsTasksVersion>
     <!-- Installer dependencies -->
     <MicrosoftNETCoreAppVersion>5.0.0-rc.1.20451.14</MicrosoftNETCoreAppVersion>
     <MicrosoftNETCoreDotNetHostVersion>5.0.0-rc.1.20451.14</MicrosoftNETCoreDotNetHostVersion>
diff --git a/eng/common/generate-locproject.ps1 b/eng/common/generate-locproject.ps1
new file mode 100644
index 00000000000..de348a2e225
--- /dev/null
+++ b/eng/common/generate-locproject.ps1
@@ -0,0 +1,110 @@
+Param(
+    [Parameter(Mandatory=$true)][string] $SourcesDirectory,     # Directory where source files live; if using a Localize directory it should live in here
+    [string] $LanguageSet = 'VS_Main_Languages',                # Language set to be used in the LocProject.json
+    [switch] $UseCheckedInLocProjectJson,                       # When set, generates a LocProject.json and compares it to one that already exists in the repo; otherwise just generates one
+    [switch] $CreateNeutralXlfs                                 # Creates neutral xlf files. Only set to false when running locally
+)
+
+# Generates LocProject.json files for the OneLocBuild task. OneLocBuildTask is described here:
+# https://ceapex.visualstudio.com/CEINTL/_wiki/wikis/CEINTL.wiki/107/Localization-with-OneLocBuild-Task
+
+Set-StrictMode -Version 2.0
+$ErrorActionPreference = "Stop"
+. $PSScriptRoot\tools.ps1
+
+Import-Module -Name (Join-Path $PSScriptRoot 'native\CommonLibrary.psm1')
+
+$exclusionsFilePath = "$SourcesDirectory\eng\Localize\LocExclusions.json"
+$exclusions = @{ Exclusions = @() }
+if (Test-Path -Path $exclusionsFilePath)
+{
+    $exclusions = Get-Content "$exclusionsFilePath" | ConvertFrom-Json
+}
+
+Push-Location "$SourcesDirectory" # push location for Resolve-Path -Relative to work
+
+# Template files
+$jsonFiles = @()
+$jsonFiles += Get-ChildItem -Recurse -Path "$SourcesDirectory" | Where-Object { $_.FullName -Match "\.template\.config\\localize\\en\..+\.json" } # .NET templating pattern
+$jsonFiles += Get-ChildItem -Recurse -Path "$SourcesDirectory" | Where-Object { $_.FullName -Match "en\\strings\.json" } # current winforms pattern
+
+$xlfFiles = @()
+
+$allXlfFiles = Get-ChildItem -Recurse -Path "$SourcesDirectory\*\*.xlf"
+$langXlfFiles = @()
+if ($allXlfFiles) {
+    $null = $allXlfFiles[0].FullName -Match "\.([\w-]+)\.xlf" # matches '[langcode].xlf'
+    $firstLangCode = $Matches.1
+    $langXlfFiles = Get-ChildItem -Recurse -Path "$SourcesDirectory\*\*.$firstLangCode.xlf"
+}
+$langXlfFiles | ForEach-Object {
+    $null = $_.Name -Match "(.+)\.[\w-]+\.xlf" # matches '[filename].[langcode].xlf
+    
+    $destinationFile = "$($_.Directory.FullName)\$($Matches.1).xlf"
+    $xlfFiles += Copy-Item "$($_.FullName)" -Destination $destinationFile -PassThru
+}
+
+$locFiles = $jsonFiles + $xlfFiles
+
+$locJson = @{
+    Projects = @(
+        @{
+            LanguageSet = $LanguageSet
+            LocItems = @(
+                $locFiles | ForEach-Object {
+                    $outputPath = "$(($_.DirectoryName | Resolve-Path -Relative) + "\")" 
+                    $continue = $true
+                    foreach ($exclusion in $exclusions.Exclusions) {
+                        if ($outputPath.Contains($exclusion))
+                        {
+                            $continue = $false
+                        }
+                    }
+                    $sourceFile = ($_.FullName | Resolve-Path -Relative)
+                    if (!$CreateNeutralXlfs -and $_.Extension -eq '.xlf') {
+                        Remove-Item -Path $sourceFile
+                    }
+                    if ($continue)
+                    {
+                        if ($_.Directory.Name -eq 'en' -and $_.Extension -eq '.json') {
+                            return @{
+                                SourceFile = $sourceFile
+                                CopyOption = "LangIDOnPath"
+                                OutputPath = "$($_.Directory.Parent.FullName | Resolve-Path -Relative)\"
+                            }
+                        }
+                        else {
+                            return @{
+                                SourceFile = $sourceFile
+                                CopyOption = "LangIDOnName"
+                                OutputPath = $outputPath
+                            }
+                        }
+                    }
+                }
+            )
+        }
+    )
+}
+
+$json = ConvertTo-Json $locJson -Depth 5
+Write-Host "LocProject.json generated:`n`n$json`n`n"
+Pop-Location
+
+if (!$UseCheckedInLocProjectJson) {
+    New-Item "$SourcesDirectory\eng\Localize\LocProject.json" -Force # Need this to make sure the Localize directory is created
+    Set-Content "$SourcesDirectory\eng\Localize\LocProject.json" $json
+}
+else {
+    New-Item "$SourcesDirectory\eng\Localize\LocProject-generated.json" -Force # Need this to make sure the Localize directory is created
+    Set-Content "$SourcesDirectory\eng\Localize\LocProject-generated.json" $json
+
+    if ((Get-FileHash "$SourcesDirectory\eng\Localize\LocProject-generated.json").Hash -ne (Get-FileHash "$SourcesDirectory\eng\Localize\LocProject.json").Hash) {
+        Write-PipelineTelemetryError -Category "OneLocBuild" -Message "Existing LocProject.json differs from generated LocProject.json. Download LocProject-generated.json and compare them."
+        
+        exit 1
+    }
+    else {
+        Write-Host "Generated LocProject.json and current LocProject.json are identical."
+    }
+}
\ No newline at end of file
diff --git a/eng/common/templates/job/onelocbuild.yml b/eng/common/templates/job/onelocbuild.yml
new file mode 100644
index 00000000000..e8bc77d2ebb
--- /dev/null
+++ b/eng/common/templates/job/onelocbuild.yml
@@ -0,0 +1,93 @@
+parameters:
+  # Optional: dependencies of the job
+  dependsOn: ''
+
+  # Optional: A defined YAML pool - https://docs.microsoft.com/en-us/azure/devops/pipelines/yaml-schema?view=vsts&tabs=schema#pool
+  pool:
+    vmImage: vs2017-win2016
+
+  CeapexPat: $(dn-bot-ceapex-package-r) # PAT for the loc AzDO instance https://dev.azure.com/ceapex
+  GithubPat: $(BotAccount-dotnet-bot-repo-PAT)
+
+  SourcesDirectory: $(Build.SourcesDirectory)
+  CreatePr: true
+  AutoCompletePr: false
+  UseLfLineEndings: true
+  UseCheckedInLocProjectJson: false
+  LanguageSet: VS_Main_Languages
+  LclSource: lclFilesInRepo
+  LclPackageId: ''
+  RepoType: gitHub
+  GitHubOrg: dotnet
+  MirrorRepo: ''
+  MirrorBranch: main
+  condition: ''
+
+jobs:
+- job: OneLocBuild
+  
+  dependsOn: ${{ parameters.dependsOn }}
+
+  displayName: OneLocBuild
+
+  pool: ${{ parameters.pool }}
+
+  variables:
+    - group: OneLocBuildVariables # Contains the CeapexPat and GithubPat
+    - name: _GenerateLocProjectArguments
+      value: -SourcesDirectory ${{ parameters.SourcesDirectory }}
+        -LanguageSet "${{ parameters.LanguageSet }}"
+        -CreateNeutralXlfs
+    - ${{ if eq(parameters.UseCheckedInLocProjectJson, 'true') }}:
+      - name: _GenerateLocProjectArguments
+        value: ${{ variables._GenerateLocProjectArguments }} -UseCheckedInLocProjectJson
+      
+
+  steps:
+    - task: Powershell@2
+      inputs:
+        filePath: $(Build.SourcesDirectory)/eng/common/generate-locproject.ps1
+        arguments: $(_GenerateLocProjectArguments)
+      displayName: Generate LocProject.json
+      condition: ${{ parameters.condition }}
+
+    - task: OneLocBuild@2
+      displayName: OneLocBuild
+      env:
+        SYSTEM_ACCESSTOKEN: $(System.AccessToken)
+      inputs:
+        locProj: eng/Localize/LocProject.json
+        outDir: $(Build.ArtifactStagingDirectory)
+        lclSource: ${{ parameters.LclSource }}
+        lclPackageId: ${{ parameters.LclPackageId }}
+        isCreatePrSelected: ${{ parameters.CreatePr }}
+        ${{ if eq(parameters.CreatePr, true) }}:
+          isAutoCompletePrSelected: ${{ parameters.AutoCompletePr }}
+          isUseLfLineEndingsSelected: ${{ parameters.UseLfLineEndings }}
+        packageSourceAuth: patAuth
+        patVariable: ${{ parameters.CeapexPat }}
+        ${{ if eq(parameters.RepoType, 'gitHub') }}:
+          repoType: ${{ parameters.RepoType }}
+          gitHubPatVariable: "${{ parameters.GithubPat }}"
+        ${{ if ne(parameters.MirrorRepo, '') }}:
+          isMirrorRepoSelected: true
+          gitHubOrganization: ${{ parameters.GitHubOrg }}
+          mirrorRepo: ${{ parameters.MirrorRepo }}
+          mirrorBranch: ${{ parameters.MirrorBranch }}
+      condition: ${{ parameters.condition }}
+
+    - task: PublishBuildArtifacts@1
+      displayName: Publish Localization Files
+      inputs:
+        PathtoPublish: '$(Build.ArtifactStagingDirectory)/loc'
+        PublishLocation: Container
+        ArtifactName: Loc
+      condition: ${{ parameters.condition }}
+
+    - task: PublishBuildArtifacts@1
+      displayName: Publish LocProject.json
+      inputs:
+        PathtoPublish: '$(Build.SourcesDirectory)/eng/Localize/'
+        PublishLocation: Container
+        ArtifactName: Loc
+      condition: ${{ parameters.condition }}
\ No newline at end of file
diff --git a/eng/common/tools.ps1 b/eng/common/tools.ps1
index 60eb601c8f3..eba7ed49d78 100644
--- a/eng/common/tools.ps1
+++ b/eng/common/tools.ps1
@@ -371,7 +371,16 @@ function InitializeVisualStudioMSBuild([bool]$install, [object]$vsRequirements =
   }
 
   $msbuildVersionDir = if ([int]$vsMajorVersion -lt 16) { "$vsMajorVersion.0" } else { "Current" }
-  return $global:_MSBuildExe = Join-Path $vsInstallDir "MSBuild\$msbuildVersionDir\Bin\msbuild.exe"
+
+  $local:BinFolder = Join-Path $vsInstallDir "MSBuild\$msbuildVersionDir\Bin"
+  $local:Prefer64bit = if (Get-Member -InputObject $vsRequirements -Name 'Prefer64bit') { $vsRequirements.Prefer64bit } else { $false }
+  if ($local:Prefer64bit -and (Test-Path(Join-Path $local:BinFolder "amd64"))) {
+    $global:_MSBuildExe = Join-Path $local:BinFolder "amd64\msbuild.exe"
+  } else {
+    $global:_MSBuildExe = Join-Path $local:BinFolder "msbuild.exe"
+  }
+
+  return $global:_MSBuildExe
 }
 
 function InitializeVisualStudioEnvironmentVariables([string] $vsInstallDir, [string] $vsMajorVersion) {
@@ -527,7 +536,7 @@ function GetDefaultMSBuildEngine() {
 
 function GetNuGetPackageCachePath() {
   if ($env:NUGET_PACKAGES -eq $null) {
-    # Use local cache on CI to ensure deterministic build. 
+    # Use local cache on CI to ensure deterministic build.
     # Avoid using the http cache as workaround for https://github.com/NuGet/Home/issues/3116
     # use global cache in dev builds to avoid cost of downloading packages.
     # For directory normalization, see also: https://github.com/NuGet/Home/issues/7968
diff --git a/global.json b/global.json
index 4fb6c96213f..d5459e34345 100644
--- a/global.json
+++ b/global.json
@@ -12,10 +12,10 @@
     "python3": "3.7.1"
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Build.Tasks.TargetFramework.Sdk": "5.0.0-beta.21160.3",
-    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.21160.3",
-    "Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk": "5.0.0-beta.21160.3",
-    "Microsoft.DotNet.Helix.Sdk": "5.0.0-beta.21160.3",
+    "Microsoft.DotNet.Build.Tasks.TargetFramework.Sdk": "5.0.0-beta.21328.3",
+    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.21328.3",
+    "Microsoft.DotNet.Build.Tasks.SharedFramework.Sdk": "5.0.0-beta.21328.3",
+    "Microsoft.DotNet.Helix.Sdk": "5.0.0-beta.21328.3",
     "Microsoft.FIX-85B6-MERGE-9C38-CONFLICT": "1.0.0",
     "Microsoft.NET.Sdk.IL": "5.0.0-preview.8.20359.4",
     "Microsoft.Build.NoTargets": "2.0.1",
diff --git a/src/coreclr/src/System.Private.CoreLib/src/System/StubHelpers.cs b/src/coreclr/src/System.Private.CoreLib/src/System/StubHelpers.cs
index b507b28559d..6949bf13642 100644
--- a/src/coreclr/src/System.Private.CoreLib/src/System/StubHelpers.cs
+++ b/src/coreclr/src/System.Private.CoreLib/src/System/StubHelpers.cs
@@ -537,6 +537,17 @@ namespace System.StubHelpers
             managed.Slice(0, numChars).CopyTo(native);
             native[numChars] = '\0';
         }
+
+        internal static unsafe string ConvertToManaged(IntPtr nativeHome, int length)
+        {
+            int end = SpanHelpers.IndexOf(ref *(char*)nativeHome, '\0', length);
+            if (end != -1)
+            {
+                length = end;
+            }
+
+            return new string((char*)nativeHome, 0, length);
+        }
     }  // class WSTRBufferMarshaler
 #if FEATURE_COMINTEROP
 
diff --git a/src/coreclr/src/vm/corelib.h b/src/coreclr/src/vm/corelib.h
index ad892439138..915c9843666 100644
--- a/src/coreclr/src/vm/corelib.h
+++ b/src/coreclr/src/vm/corelib.h
@@ -1050,6 +1050,7 @@ DEFINE_METHOD(CSTRMARSHALER,        CLEAR_NATIVE,           ClearNative,
 
 DEFINE_CLASS(FIXEDWSTRMARSHALER,   StubHelpers,            FixedWSTRMarshaler)
 DEFINE_METHOD(FIXEDWSTRMARSHALER,  CONVERT_TO_NATIVE,      ConvertToNative,            SM_Str_IntPtr_Int_RetVoid)
+DEFINE_METHOD(FIXEDWSTRMARSHALER,  CONVERT_TO_MANAGED,     ConvertToManaged,           SM_IntPtr_Int_RetStr)
 
 DEFINE_CLASS(BSTRMARSHALER,         StubHelpers,            BSTRMarshaler)
 DEFINE_METHOD(BSTRMARSHALER,        CONVERT_TO_NATIVE,      ConvertToNative,            SM_Str_IntPtr_RetIntPtr)
diff --git a/src/coreclr/src/vm/ilmarshalers.cpp b/src/coreclr/src/vm/ilmarshalers.cpp
index e0eb8c558d1..21cff7aa1a7 100644
--- a/src/coreclr/src/vm/ilmarshalers.cpp
+++ b/src/coreclr/src/vm/ilmarshalers.cpp
@@ -1909,11 +1909,8 @@ void ILFixedWSTRMarshaler::EmitConvertContentsNativeToCLR(ILCodeStream* pslILEmi
     STANDARD_VM_CONTRACT;
 
     EmitLoadNativeHomeAddr(pslILEmit);
-    pslILEmit->EmitDUP();
-    pslILEmit->EmitCALL(METHOD__STRING__WCSLEN, 1, 1);
-    pslILEmit->EmitCALL(METHOD__STUBHELPERS__CHECK_STRING_LENGTH, 1, 0);
-
-    pslILEmit->EmitNEWOBJ(METHOD__STRING__CTOR_CHARPTR, 1);
+    pslILEmit->EmitLDC(m_pargs->fs.fixedStringLength);
+    pslILEmit->EmitCALL(METHOD__FIXEDWSTRMARSHALER__CONVERT_TO_MANAGED, 2, 1);
     EmitStoreManagedValue(pslILEmit);
 }
 
diff --git a/src/tests/Interop/StringMarshalling/LPTSTR/LPTSTRTest.cs b/src/tests/Interop/StringMarshalling/LPTSTR/LPTSTRTest.cs
index 8c789d180c6..a29b99a01c4 100644
--- a/src/tests/Interop/StringMarshalling/LPTSTR/LPTSTRTest.cs
+++ b/src/tests/Interop/StringMarshalling/LPTSTR/LPTSTRTest.cs
@@ -60,5 +60,20 @@ class LPTStrTest
         ReverseByValStringUni(ref uniStr);
 
         Assert.AreEqual(Helpers.Reverse(InitialString), uniStr.str);
+
+        ReverseCopyByValStringAnsi(new ByValStringInStructAnsi { str = LongString }, out ByValStringInStructSplitAnsi ansiStrSplit);
+
+        Assert.AreEqual(Helpers.Reverse(LongString[^10..]), ansiStrSplit.str1);
+        Assert.AreEqual(Helpers.Reverse(LongString[..^10]), ansiStrSplit.str2);
+
+        ReverseCopyByValStringUni(new ByValStringInStructUnicode { str = LongString }, out ByValStringInStructSplitUnicode uniStrSplit);
+
+        Assert.AreEqual(Helpers.Reverse(LongString[^10..]), uniStrSplit.str1);
+        Assert.AreEqual(Helpers.Reverse(LongString[..^10]), uniStrSplit.str2);
+
+        ReverseCopyByValStringUni(new ByValStringInStructUnicode { str = LongUnicodeString }, out ByValStringInStructSplitUnicode uniStrSplit2);
+
+        Assert.AreEqual(Helpers.Reverse(LongUnicodeString[^10..]), uniStrSplit2.str1);
+        Assert.AreEqual(Helpers.Reverse(LongUnicodeString[..^10]), uniStrSplit2.str2);
     }
 }
diff --git a/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cpp b/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cpp
index 428ce488ddd..c618a5db4fb 100644
--- a/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cpp
+++ b/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cpp
@@ -47,3 +47,15 @@ extern "C" DLL_EXPORT void STDMETHODCALLTYPE ReverseByValStringUni(ByValStringIn
 {
     StringMarshalingTests<LPWSTR, TP_slen>::ReverseInplace(str->str);
 }
+
+extern "C" DLL_EXPORT void STDMETHODCALLTYPE ReverseCopyByValStringAnsi(ByValStringInStructAnsi str, ByValStringInStructAnsi* out)
+{
+    *out = str;
+    StringMarshalingTests<char*, default_callconv_strlen>::ReverseInplace(out->str);
+}
+
+extern "C" DLL_EXPORT void STDMETHODCALLTYPE ReverseCopyByValStringUni(ByValStringInStructUnicode str, ByValStringInStructUnicode* out)
+{
+    *out = str;
+    StringMarshalingTests<LPWSTR, TP_slen>::ReverseInplace(out->str);
+}
diff --git a/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cs b/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cs
index 022c3dc250e..522c80e872f 100644
--- a/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cs
+++ b/src/tests/Interop/StringMarshalling/LPTSTR/LPTStrTestNative.cs
@@ -14,6 +14,15 @@ class LPTStrTestNative
         public string str;
     }
 
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
+    public struct ByValStringInStructSplitAnsi
+    {
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
+        public string str1;
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
+        public string str2;
+    }
+
     [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
     public struct ByValStringInStructUnicode
     {
@@ -21,6 +30,15 @@ class LPTStrTestNative
         public string str;
     }
 
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
+    public struct ByValStringInStructSplitUnicode
+    {
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
+        public string str1;
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
+        public string str2;
+    }
+
     [DllImport(nameof(LPTStrTestNative), CharSet = CharSet.Unicode)]
     public static extern bool Verify_NullTerminators_PastEnd(StringBuilder builder, int length);