use the sdk.paths mechanism from .NET 10p3 (#49627)

Author: baronfel

eng/pipelines/templates/jobs/sdk-build.yml

@@ -104,10 +104,10 @@ jobs:
         env:
           BuildConfig: $(buildConfiguration)
           TestFullMSBuild: ${{ parameters.testFullMSBuild }}
-          
+
       - powershell: build/RunTestTemplateTests.ps1
         displayName: 🟣 Run Test Templates Tests
-        
+
     - ${{ else }}:
       - script: |
           source $(Build.SourcesDirectory)/eng/common/native/init-os-and-arch.sh
@@ -137,6 +137,7 @@ jobs:
       - ${{ if eq(parameters.runAoTTests, true) }}:
         # For the reason this is here, see: https://github.com/dotnet/sdk/issues/22655
         - script: $(Build.SourcesDirectory)/artifacts/bin/redist/$(buildConfiguration)/dotnet/dotnet workload install wasm-tools --skip-manifest-update
+          workingDirectory: $(Build.SourcesDirectory)/artifacts
           displayName: 🟣 Install wasm-tools Workload
       # For the /p:Projects syntax for PowerShell, see: https://github.com/dotnet/msbuild/issues/471#issuecomment-1146466335
       - ${{ if eq(parameters.pool.os, 'windows') }}:

global.json

@@ -1,4 +1,11 @@
 {
+  "sdk": {
+    "paths": [
+      ".dotnet",
+      "$host$"
+    ],
+    "errorMessage": "The .NET SDK is not installed or is not configured correctly. Please run ./build to install the correct SDK version locally."
+  },
   "tools": {
     "dotnet": "10.0.100-preview.6.25315.102",
     "runtimes": {

src/Layout/redist/redist.csproj

@@ -117,5 +117,4 @@
   </Target>
 
   <Target Name="ReturnProductVersion" Returns="$(FullNugetVersion)" />
-
 </Project>

src/Layout/redist/targets/Directory.Build.targets

@@ -21,6 +21,7 @@
     <Import Project="GenerateArchives.targets" />
 
     <Import Project="OverlaySdkOnLKG.targets" />
+    <Import Project="GenerateTestingGlobalJson.targets" />
   </ImportGroup>
 
   <!-- Installers -->

src/Layout/redist/targets/GenerateTestingGlobalJson.targets

@@ -0,0 +1,33 @@
+<Project>
+  <PropertyGroup>
+    <!-- We put this in the root of the artifacts dir so that any usage (not just from ./tmp, but also from ./bin) gets redirected. -->
+    <_TestingGlobalJsonPath>$(ArtifactsDir)global.json</_TestingGlobalJsonPath>
+  </PropertyGroup>
+
+  <!-- Since the dotnet binary respects sdk.paths in global.json now, and we use this in the repo root to make sure that we consistently use the repo-local
+       SDK for building/etc, we need to put something in place so that tests don't use the repo-local SDK and instead use the redist SDK. -->
+  <Target Name="CreateRedistGlobalJsonForTesting"
+    BeforeTargets="AfterBuild"
+    Outputs="$(_TestingGlobalJsonPath)">
+    <PropertyGroup>
+      <_TestingRedistDotnetPath>$(TestHostDotNetRoot.Replace('\', '\\'))</_TestingRedistDotnetPath>
+    </PropertyGroup>
+    <ItemGroup>
+      <_RedistGlobalJsonLines Include="{" />
+      <_RedistGlobalJsonLines Include="  &quot;sdk&quot;: {" />
+      <_RedistGlobalJsonLines Include="    &quot;paths&quot;: [" />
+      <_RedistGlobalJsonLines Include="      &quot;$(_TestingRedistDotnetPath)&quot;" />
+      <_RedistGlobalJsonLines Include="    ]" />
+      <_RedistGlobalJsonLines Include="  }" />
+      <_RedistGlobalJsonLines Include="}" />
+    </ItemGroup>
+    <WriteLinesToFile File="$(_TestingGlobalJsonPath)"
+                       Lines="@(_RedistGlobalJsonLines)"
+                       Overwrite="true"
+                       Encoding="utf-8"
+                       WriteOnlyWhenDifferent="true" />
+    <ItemGroup>
+      <FileWrites Include="$(_TestingGlobalJsonPath)" />
+    </ItemGroup>
+  </Target>
+</Project>