Enable `/warnAsError` (#23072)

* Enable `/warnAsError` in Windows builds
  - already enabled in non-Windows builds because override existed only in build.ps1
* Allow some warnings related to closed issues
  - common `<NoWarn>$(NoWarn);CS1591</NoWarn>` case unchanged
    - /Directory.Build.props ensures that warning remains a warning but doesn't hide it
* !fixup! Root build.sh _does_ disable warnings as errors
  - variable eng/common/tools.sh uses named `warn_as_error`

Directory.Build.props

@@ -101,14 +101,11 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <!-- Don't make missing XML docs a fatal build error, but still surface so we have visibility into undocumented APIs. -->
     <WarningsNotAsErrors>$(WarningsNotAsErrors);CS1591</WarningsNotAsErrors>
+
     <!-- xUnit1004 = warns about skipped tests. Make this a non-fatal build warning. -->
     <WarningsNotAsErrors>$(WarningsNotAsErrors);xUnit1004</WarningsNotAsErrors>
-    <!-- Working around https://github.com/NuGet/Home/issues/8467 -->
-    <NoWarn>$(NoWarn);NU5131</NoWarn>
-    <!-- Needed until we resolve https://github.com/dotnet/aspnetcore-internal/issues/3103 -->
-    <NoWarn>$(NoWarn);NU5048</NoWarn>
 
-    <!-- TODO: Figure out why these warnings are occuring -->
+    <!-- Ignore specific Roslyn warnings for now, https://github.com/dotnet/aspnetcore/issues/22090 -->
     <NoWarn Condition="'$(IsAnalyzersProject)' == 'true'">$(NoWarn);RS1024;RS1025;RS1026</NoWarn>
   </PropertyGroup>
 

build.ps1

@@ -358,17 +358,12 @@ if (-not $foundJdk -and $RunBuild -and ($All -or $BuildJava) -and -not $NoBuildJ
 # Initialize global variables need to be set before the import of Arcade is imported
 $restore = $RunRestore
 
-# Though VS Code may indicate $nodeReuse, $warnAsError and $msbuildEngine are unused, tools.ps1 uses them.
+# Though VS Code may indicate $nodeReuse and $msbuildEngine are unused, tools.ps1 uses them.
 
 # Disable node reuse - Workaround perpetual issues in node reuse and custom task assemblies
 $nodeReuse = $false
 $env:MSBUILDDISABLENODEREUSE=1
 
-# Our build often has warnings that we can't fix, like "MSB3026: Could not copy" due to race
-# conditions in building C++
-# Fixing this is tracked by https://github.com/dotnet/aspnetcore-internal/issues/601
-$warnAsError = $false
-
 # Use `dotnet msbuild` by default
 $msbuildEngine = 'dotnet'
 

build.sh

@@ -306,10 +306,6 @@ restore=$run_restore
 nodeReuse=false
 export MSBUILDDISABLENODEREUSE=1
 
-# Our build often has warnings that we can't fix
-# Fixing this is tracked by https://github.com/dotnet/aspnetcore-internal/issues/601
-warn_as_error=false
-
 # Ensure passing neither --bl nor --nobl on CI avoids errors in tools.sh. This is needed because we set both variables
 # to false by default i.e. they always exist. (We currently avoid binary logs but that is made visible in the YAML.)
 if [[ "$ci" == true && "$exclude_ci_binary_log" == false ]]; then

eng/Workarounds.props

@@ -18,13 +18,6 @@
     <TestRunnerAdditionalArguments>$(TestRunnerAdditionalArguments) -nocolor</TestRunnerAdditionalArguments>
   </PropertyGroup>
 
-  <PropertyGroup>
-    <!-- Working around https://github.com/NuGet/Home/issues/8467 -->
-    <NoWarn>$(NoWarn);NU5131</NoWarn>
-    <!-- Workaround until https://github.com/dotnet/aspnetcore-internal/issues/3103 is resolved -->
-    <NoWarn>$(NoWarn);NU5048</NoWarn>
-  </PropertyGroup>
-
   <!-- Workaround https://github.com/dotnet/roslyn/issues/27975 -->
   <PropertyGroup>
     <!-- We use the compiler toolset that comes from NuGet Packages rather than the SDK built-in.

src/Mvc/Mvc.Razor.RuntimeCompilation/src/Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.csproj

@@ -4,9 +4,6 @@
     <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
     <NoWarn>$(NoWarn);CS1591</NoWarn>
 
-    <!-- !!! Temporary workaround while we switch TFMs. -->
-    <NoWarn>$(NoWarn);NU5129</NoWarn>
-
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;aspnetcoremvc;razor</PackageTags>
     <IsPackable>true</IsPackable>

src/Razor/Microsoft.NET.Sdk.Razor/src/Microsoft.NET.Sdk.Razor.csproj

@@ -13,8 +13,6 @@
     <NoWarn>$(NoWarn);NU5100</NoWarn>
     <!-- It is intentional to not include build/netstandard2.0/Microsoft.NET.Sdk.Razor.targets -->
     <NoWarn>$(NoWarn);NU5129</NoWarn>
-    <!-- Ignore file copy warnings -->
-    <NoWarn>$(NoWarn);MSB3030;MSB4181</NoWarn>
     <!-- Cannot run pubternal check on net46 -->
     <DisablePubternalApiCheck>true</DisablePubternalApiCheck>
     <!-- Need to build this project in source build -->

src/Razor/test/testassets/Directory.Build.props

@@ -26,9 +26,6 @@
 
     <!-- Working around an issue in XDT transforms -->
     <AspNetCoreHostingModel>OutOfProcess</AspNetCoreHostingModel>
-
-    <!-- Working around https://github.com/NuGet/Home/issues/8467 -->
-    <NoWarn>$(NoWarn);NU5131</NoWarn>
   </PropertyGroup>
 
   <!-- Don't use the server when building in place. This locks up rzc.dll -->