Fix 4 more bad delegates missing the attribute that cause iOS AOT errors at runtime (#18390)

### Description
<!-- Describe your changes. -->
Fix bad delegates.
Add script to detect mismatch, and run in CI and when creating nuget
package.

Ignore whitespace when looking at the diff to the .cs file as
clang-format ran.

### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
#18363

csharp/OnnxRuntime.CSharp.proj

@@ -92,6 +92,13 @@ CMake creates a target to this project
   </Target>
 
   <Target Name="CreatePackage">
+    <!-- Validate no missing UnmanagedFunctionPointer attributes on delegates. -->
+    <Exec Condition="'$(IsWindowsBuild)' == 'true' AND $(OrtPackageId) == 'Microsoft.ML.OnnxRuntime'"
+          Command="$(PythonExe) tools/ValidateNativeDelegateAttributes.py"
+          ContinueOnError="False">
+        <Output TaskParameter="ConsoleOutput" PropertyName="GenerateNuspecOutput" />
+    </Exec>
+
     <!-- Create Microsoft.ML.OnnxRuntime.Managed with the C# bindings using the C# project -->
     <Message Importance="High" Text="Creating Microsoft.ML.OnnxRuntime.Managed nuget package..." />
     <MSBuild Projects="src\Microsoft.ML.OnnxRuntime\Microsoft.ML.OnnxRuntime.csproj"
@@ -100,8 +107,8 @@ CMake creates a target to this project
 
     <!-- Manually create the nuspec for the native Microsoft.ML.OnnxRuntime package -->
     <Message Importance="High" Text="Generating nuspec for the native Microsoft.ML.OnnxRuntime nuget package..." />
-    <Exec Command="$(PythonExe) $(GenerateNuspecScript) --package_version $(PackageVersion) --package_name $(OrtPackageId) --target_architecture $(TargetArchitecture) --build_config $(Configuration) --native_build_path $(NativeBuildOutputDirAbs) --packages_path $(OnnxRuntimePackagesDirectoryAbs) --ort_build_path $(OnnxRuntimeBuildDirectoryAbs) --sources_path $(OnnxRuntimeSourceDirectoryAbs) --commit_id $(GitCommitHash) --is_release_build $(IsReleaseBuild) --execution_provider $(ExecutionProvider)" 
-          ContinueOnError="False" 
+    <Exec Command="$(PythonExe) $(GenerateNuspecScript) --package_version $(PackageVersion) --package_name $(OrtPackageId) --target_architecture $(TargetArchitecture) --build_config $(Configuration) --native_build_path $(NativeBuildOutputDirAbs) --packages_path $(OnnxRuntimePackagesDirectoryAbs) --ort_build_path $(OnnxRuntimeBuildDirectoryAbs) --sources_path $(OnnxRuntimeSourceDirectoryAbs) --commit_id $(GitCommitHash) --is_release_build $(IsReleaseBuild) --execution_provider $(ExecutionProvider)"
+          ContinueOnError="False"
           ConsoleToMSBuild="true">
         <Output TaskParameter="ConsoleOutput" PropertyName="GenerateNuspecOutput" />
     </Exec>
@@ -109,9 +116,9 @@ CMake creates a target to this project
     <!-- run `nuget pack` on Windows or `dotnet pack` on Linux to create the native nupkg -->
     <Message Importance="High" Text="Bundling native shared library artifacts into Microsoft.ML.OnnxRuntime nuget package..." />
     <Exec Condition=" '$(IsWindowsBuild)' == 'true'"
-          Command="$(NugetExe) pack NativeNuget.nuspec" 
+          Command="$(NugetExe) pack NativeNuget.nuspec"
           WorkingDirectory="$(NativeBuildOutputDirAbs)"
-          ContinueOnError="False" 
+          ContinueOnError="False"
           ConsoleToMSBuild="true">
       <Output TaskParameter="ConsoleOutput" PropertyName="OutputOfExec" />
     </Exec>
@@ -119,11 +126,11 @@ CMake creates a target to this project
     <!-- build.py uses dotnet to build on linux so we know it's available.
          nuget needs to be run using mono to work correctly, but installing mono on WSL breaks interop
          (see https://github.com/microsoft/WSL/issues/8531). in order to play nicely with both we use `dotnet pack`
-         to pack the native nuget package using a stub csproj to provide the nuspec file path. 
+         to pack the native nuget package using a stub csproj to provide the nuspec file path.
     -->
     <Exec Condition="'$(IsLinuxBuild)' == 'true'"
-          Command="dotnet pack tools/linux_pack/LinuxPackNativeNuget.csproj /p:Configuration=$(Configuration) /p:OnnxRuntimeBuildDirectory=$(NativeBuildOutputDirAbs)" 
-          ContinueOnError="False" 
+          Command="dotnet pack tools/linux_pack/LinuxPackNativeNuget.csproj /p:Configuration=$(Configuration) /p:OnnxRuntimeBuildDirectory=$(NativeBuildOutputDirAbs)"
+          ContinueOnError="False"
           ConsoleToMSBuild="true" >
       <Output TaskParameter="ConsoleOutput" PropertyName="OutputOfExec" />
     </Exec>

csharp/tools/ValidateNativeDelegateAttributes.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+
+import argparse
+import pathlib
+
+
+def check_all_delegates_have_unmanaged_function_pointer_attribute(file: pathlib.Path):
+    """
+    Check that all 'public delegate' declarations have a matching UnmanagedFunctionPointer attribute.
+    :param file: C# source file to check.
+    :return: Number of errors
+    """
+
+    print(f"Checking {file!s}")
+
+    errors = 0
+    line_num = 0
+    with open(str(file.resolve(strict=True))) as f:
+        prev_line = ""
+        for line in f.readlines():
+            line_num += 1
+
+            # strip so it's easier to deal with commented out lines.
+            line = line.strip()  # noqa
+            if line.startswith("public delegate ") and not prev_line.startswith("[UnmanagedFunctionPointer"):
+                errors += 1
+                print(f"Line {line_num} is missing UnmanagedFunctionPointer attribute:\n\t{prev_line}\n\t{line}")
+
+            prev_line = line
+
+    return errors
+
+
+def main():
+    arg_parser = argparse.ArgumentParser(
+        "Script to validate that the native delegates for the ONNX Runtime C# managed projects have the required "
+        "attributes for iOS AOT. Paths are inferred from the script location."
+        "Errors of this nature can only be detected at runtime, in a release build, of a Xamarin/MAUI app, "
+        "on an actual iOS device. Due to that we take extra steps to identify problems early."
+    )
+
+    # no real args. just using this to provide description as help message
+    _ = arg_parser.parse_args()
+
+    # CI needs resolve() as __file__ is a relative path when the script is run there
+    script_dir = pathlib.Path(__file__).resolve().parent
+    csharp_root = script_dir.parent
+
+    managed_dir = csharp_root / "src" / "Microsoft.ML.OnnxRuntime"
+    native_methods = managed_dir / "NativeMethods.shared.cs"
+    training_native_methods = managed_dir / "Training" / "NativeTrainingMethods.shared.cs"
+    errors = check_all_delegates_have_unmanaged_function_pointer_attribute(native_methods)
+    errors += check_all_delegates_have_unmanaged_function_pointer_attribute(training_native_methods)
+
+    if errors:
+        raise ValueError(f"{errors} errors were found. Please check output for specifics.")
+
+
+if __name__ == "__main__":
+    main()

tools/ci_build/github/azure-pipelines/templates/jobs/win-ci-vs-2022-job.yml

@@ -175,6 +175,11 @@ jobs:
       msbuildArguments: '-t:restore -p:OrtPackageId=$(OrtPackageId)'
       workingDirectory: '$(Build.SourcesDirectory)\csharp'
 
+  - script: |
+      python3 tools\ValidateNativeDelegateAttributes.py
+    displayName: 'Validate C# native delegates'
+    workingDirectory: '$(Build.SourcesDirectory)\csharp'
+
   - task: MSBuild@1
     displayName: 'Build C#'
     inputs: