Add AOT compatibility for net8.0 TFM (#197)

## Summary

Makes IntelliTect.Multitool AOT-compatible so that consumers on .NET 8+
can publish with NativeAOT or trimming without warnings originating from
this library. Older consumers on `netstandard2.1` are unaffected.

## Changes

### Multi-target `netstandard2.1;net8.0`
NuGet automatically selects the best matching TFM — `net8.0+` consumers
get the AOT-annotated assembly; older consumers fall back to
`netstandard2.1`.

### `IsAotCompatible` for net7.0+ TFMs
```xml
<IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net7.0'))">true</IsAotCompatible>
```
Enables the AOT, trim, and single-file analyzers for `net8.0` (and any
future TFMs added). Uses `IsTargetFrameworkCompatible` instead of a
hardcoded equality check so it automatically applies to `net10.0`, etc.

### Fix non-generic reflection in `ReleaseDateAttribute.GetReleaseDate`
```csharp
// Before — non-generic, causes IL2070 trim warning
object[]? attribute = assembly?.GetCustomAttributes(typeof(ReleaseDateAttribute), false);

// After — generic, trimmer can statically resolve the type
return assembly?.GetCustomAttribute<ReleaseDateAttribute>()?.ReleaseDate;
```

### Null guard in `RepositoryPaths.GetDefaultRepoRoot`
Added `&& projectPath is not null` to guard against the dictionary
returning a null value — required for correctness under `net8.0`'s
stricter nullable annotations with `TreatWarningsAsErrors`.

## Verification
- ✅ Build passes with zero warnings across `netstandard2.1`, `net8.0`,
and `net10.0` (test project)
- ✅ `TreatWarningsAsErrors=true` — all AOT/trim analyzers ran clean
- ✅ 30/32 tests pass; 2 pre-existing failures are unrelated worktree
path tests

Author: BenjaminMichaelis

.github/workflows/build-and-test.yml

@@ -37,8 +37,27 @@ jobs:
         trx-file-path: '${{ runner.temp }}/*.trx'
         output-directory: '${{ runner.temp }}/vsplaylists'
 
+  aot-test:
+    name: AOT publish test
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: bash
+    steps:
+    - uses: actions/checkout@v6
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v5
+      with:
+        global-json-file: global.json
+    - name: Install NativeAOT prerequisites
+      run: sudo apt-get install -y clang zlib1g-dev
+    - name: Publish AOT
+      run: dotnet publish IntelliTect.Multitool.AotTest/IntelliTect.Multitool.AotTest.csproj -r linux-x64 -c Release
+    - name: Run AOT binary
+      run: ./IntelliTect.Multitool.AotTest/bin/Release/net8.0/linux-x64/publish/IntelliTect.Multitool.AotTest
+
   automerge:
-    needs: [build-and-test]
+    needs: [build-and-test, aot-test]
     runs-on: ubuntu-latest
 
     permissions:

IntelliTect.Multitool.AotTest/IntelliTect.Multitool.AotTest.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <PublishAot>true</PublishAot>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\IntelliTect.Multitool\IntelliTect.Multitool.csproj" />
+  </ItemGroup>
+</Project>

IntelliTect.Multitool.AotTest/Program.cs

@@ -0,0 +1,27 @@
+using IntelliTect.Multitool;
+using IntelliTect.Multitool.Extensions;
+
+// StringExtensions
+bool slugOk = "Hello, World!".CreateUrlSlug() == "hello-world";
+bool urlOk = "https://github.com/IntelliTect".ValidateUrlString();
+
+// SystemLinqExtensions
+string?[] items = ["a", null, "b", null, "c"];
+bool filterOk = items.WhereNotNull().Count() == 3;
+
+// ReleaseDateAttribute — returns null since no attribute on this assembly,
+// but exercises the AOT-safe (statically-known type) GetCustomAttribute<T> code path
+DateTime? releaseDate = ReleaseDateAttribute.GetReleaseDate();
+bool attributeOk = releaseDate is null;
+
+if (!slugOk || !urlOk || !filterOk || !attributeOk)
+{
+    Console.Error.WriteLine("AOT test FAILED.");
+    return 1;
+}
+
+// RepositoryPaths is excluded: its static initializer reads a build-time temp file
+// that doesn't exist at AOT runtime. The class is AOT-compatible (file I/O + LINQ only).
+
+Console.WriteLine("AOT test passed.");
+return 0;

IntelliTect.Multitool.slnx

@@ -7,6 +7,7 @@
     <File Path="global.json" />
     <File Path="README.md" />
   </Folder>
+  <Project Path="IntelliTect.Multitool.AotTest/IntelliTect.Multitool.AotTest.csproj" />
   <Project Path="IntelliTect.Multitool.Tests/IntelliTect.Multitool.Tests.csproj" />
   <Project Path="IntelliTect.Multitool/IntelliTect.Multitool.csproj" />
 </Solution>

IntelliTect.Multitool/IntelliTect.Multitool.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
 	<PropertyGroup>
-		<TargetFramework>netstandard2.1</TargetFramework>
+		<TargetFrameworks>netstandard2.1;net8.0</TargetFrameworks>
 		<OutputType>Library</OutputType>
 		<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
 		<GenerateDocumentationFile>true</GenerateDocumentationFile>
@@ -13,6 +13,7 @@
 		<PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
 		<NeutralLanguage>en</NeutralLanguage>
 		<Version>1.0.1</Version>
+		<IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">true</IsAotCompatible>
 	</PropertyGroup>
 	<ItemGroup>
 		<CodeAnalysisDictionary Include="CustomDictionary.xml" />

IntelliTect.Multitool/ReleaseDateAttribute.cs

@@ -22,8 +22,7 @@ public class ReleaseDateAttribute(string utcDateString) : Attribute
     /// <returns>The date time from the assembly attribute</returns>
     public static DateTime? GetReleaseDate(Assembly? assembly = null)
     {
-        object[]? attribute = (assembly ?? Assembly.GetEntryAssembly())?.GetCustomAttributes(typeof(ReleaseDateAttribute), false);
-        return attribute?.Length >= 1 ? ((ReleaseDateAttribute)attribute[0]).ReleaseDate : null;
+        return (assembly ?? Assembly.GetEntryAssembly())?.GetCustomAttribute<ReleaseDateAttribute>()?.ReleaseDate;
     }
 
 }

IntelliTect.Multitool/RepositoryPaths.cs

@@ -43,7 +43,7 @@ public static string GetDefaultRepoRoot()
             }
         }
         // Search from the project directory if we are live unit testing or if the initial search failed.
-        if (BuildVariables.TryGetValue("ProjectPath", out string? projectPath))
+        if (BuildVariables.TryGetValue("ProjectPath", out string? projectPath) && !string.IsNullOrWhiteSpace(projectPath))
         {
             searchStartDirectory = new FileInfo(projectPath).Directory;
             if (TrySearchForGitContainingDirectory(searchStartDirectory, out gitDirectory)