detect dependencies with restore property to work around NuGet bug

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core.Test/Discover/DiscoveryWorkerTests.cs

@@ -1381,4 +1381,57 @@ await TestDiscoveryAsync(
             }
         );
     }
+
+    // If the "Restore" target is invoked and $(RestoreUseStaticGraphEvaluation) is set to true, NuGet can throw
+    // a NullReferenceException.
+    // https://github.com/NuGet/Home/issues/11761#issuecomment-1105218996
+    [Fact]
+    public async Task NullReferenceExceptionFromNuGetRestoreIsWorkedAround()
+    {
+        await TestDiscoveryAsync(
+            packages: [
+                MockNuGetPackage.CreateSimplePackage("Some.Package", "1.2.3", "net8.0"),
+            ],
+            experimentsManager: new ExperimentsManager() { UseDirectDiscovery = true },
+            workspacePath: "",
+            files: [
+                ("project.csproj", """
+                    <Project Sdk="Microsoft.NET.Sdk">
+                      <PropertyGroup>
+                        <TargetFramework>net8.0</TargetFramework>
+                        <RestoreUseStaticGraphEvaluation>true</RestoreUseStaticGraphEvaluation>
+                      </PropertyGroup>
+                      <ItemGroup>
+                        <PackageReference Include="Some.Package" Version="1.2.3" />
+                      </ItemGroup>
+                    </Project>
+                    """),
+                // a pattern seen in the wild; always run restore
+                ("Directory.Build.rsp", """
+                    /Restore
+                    """)
+            ],
+            expectedResult: new()
+            {
+                Path = "",
+                Projects = [
+                    new()
+                    {
+                        FilePath = "project.csproj",
+                        TargetFrameworks = ["net8.0"],
+                        Dependencies = [
+                            new("Some.Package", "1.2.3", DependencyType.PackageReference, TargetFrameworks: ["net8.0"], IsDirect: true)
+                        ],
+                        Properties = [
+                            new("RestoreUseStaticGraphEvaluation", "true", "project.csproj"),
+                            new("TargetFramework", "net8.0", "project.csproj"),
+                        ],
+                        ReferencedProjectPaths = [],
+                        ImportedFiles = [],
+                        AdditionalFiles = [],
+                    }
+                ]
+            }
+        );
+    }
 }

nuget/helpers/lib/NuGetUpdater/NuGetUpdater.Core/Discover/SdkProjectDiscovery.cs

@@ -101,7 +101,7 @@ public static async Task<ImmutableArray<ProjectDiscoveryResult>> DiscoverWithBin
                 {
                     // the built-in target `GenerateBuildDependencyFile` forces resolution of all NuGet packages, but doesn't invoke a full build
                     var dependencyDiscoveryTargetsPath = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)!, "DependencyDiscovery.targets");
-                    var args = new string[]
+                    var args = new List<string>()
                     {
                         "build",
                         startingProjectPath,
@@ -112,6 +112,16 @@ public static async Task<ImmutableArray<ProjectDiscoveryResult>> DiscoverWithBin
                         $"/bl:{binLogPath}"
                     };
                     var (exitCode, stdOut, stdErr) = await ProcessEx.RunDotnetWithoutMSBuildEnvironmentVariablesAsync(args, startingProjectDirectory, experimentsManager);
+                    if (exitCode != 0 && stdOut.Contains("error : Object reference not set to an instance of an object."))
+                    {
+                        // https://github.com/NuGet/Home/issues/11761#issuecomment-1105218996
+                        // Due to a bug in NuGet, there can be a null reference exception thrown and adding this command line argument will work around it,
+                        // but this argument can't always be added; it can cause problems in other instances, so we're taking the approach of not using it
+                        // unless we have to.
+                        args.Add("/RestoreProperty:__Unused__=__Unused__");
+                        (exitCode, stdOut, stdErr) = await ProcessEx.RunDotnetWithoutMSBuildEnvironmentVariablesAsync(args, startingProjectDirectory, experimentsManager);
+                    }
+
                     return (exitCode, stdOut, stdErr);
                 }, logger, retainMSBuildSdks: true);
                 MSBuildHelper.ThrowOnError(stdOut);