fix: isolate project outputs and prevent file locking during builds

Author: dborgards

Directory.Build.props

@@ -15,4 +15,9 @@
     <!-- Suppress upgrade warning - we're using SDK's built-in analyzers -->
     <_SkipUpgradeNetAnalyzersNuGetWarning>true</_SkipUpgradeNetAnalyzersNuGetWarning>
   </PropertyGroup>
+
+  <PropertyGroup>
+    <!-- Give each project its own obj directory to avoid cross-project locking -->
+    <BaseIntermediateOutputPath Condition="'$(BaseIntermediateOutputPath)' == ''">$(MSBuildProjectDirectory)/obj/$(MSBuildProjectName)/</BaseIntermediateOutputPath>
+  </PropertyGroup>
 </Project>

src/CycloneDX.MSBuild/CycloneDX.MSBuild.csproj

@@ -32,6 +32,14 @@
     </PackageReleaseNotes>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(IsTopLevelBuildProject)' != 'true'">
+    <!-- When this project is built transitively we isolate its output to avoid file locking -->
+    <CycloneDXParallelOutputRoot>$(MSBuildProjectDirectory)/bin/$(Configuration)/$(TargetFramework)/_references/$(MSBuildNodeId)/</CycloneDXParallelOutputRoot>
+    <OutputPath>$(CycloneDXParallelOutputRoot)</OutputPath>
+    <!-- Skip package generation for dependency builds to prevent repeated pack operations -->
+    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
+  </PropertyGroup>
+
   <ItemGroup>
     <!-- Include build files in package -->
     <None Include="build\**" Pack="true" PackagePath="build\" />

tests/CycloneDX.MSBuild.Tests/CycloneDX.MSBuild.Tests.csproj

@@ -30,6 +30,7 @@
     <!-- This prevents parallel builds of the shared dependency that cause file locking -->
     <ProjectReference Include="../../src/CycloneDX.MSBuild/CycloneDX.MSBuild.csproj">
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+      <BuildInParallel>false</BuildInParallel>
       <Properties>GeneratePackageOnBuild=false</Properties>
     </ProjectReference>
 

tests/Directory.Build.props

@@ -15,6 +15,5 @@
     <!-- Use project-specific intermediate output directories to prevent parallel build conflicts -->
     <!-- This ensures each project has its own obj/ directory even when building shared dependencies -->
     <BaseIntermediateOutputPath>$(MSBuildProjectDirectory)/obj/$(MSBuildProjectName)/</BaseIntermediateOutputPath>
-    <IntermediateOutputPath>$(BaseIntermediateOutputPath)$(Configuration)/</IntermediateOutputPath>
   </PropertyGroup>
 </Project>