Populate XML doc comments into OpenAPI document

eng/Dependencies.props

@@ -223,6 +223,7 @@ and are generated based on the last package release.
     <LatestPackageReference Include="StackExchange.Redis" />
     <LatestPackageReference Include="Swashbuckle.AspNetCore" />
     <LatestPackageReference Include="System.Reactive.Linq" />
+    <LatestPackageReference Include="Verify.SourceGenerators" />
     <LatestPackageReference Include="Verify.Xunit" />
     <LatestPackageReference Include="xunit.abstractions" />
     <LatestPackageReference Include="xunit.analyzers" />

eng/Versions.props

@@ -326,6 +326,7 @@
     <StackExchangeRedisVersion>2.7.27</StackExchangeRedisVersion>
     <SystemReactiveLinqVersion>5.0.0</SystemReactiveLinqVersion>
     <SwashbuckleAspNetCoreVersion>6.6.2</SwashbuckleAspNetCoreVersion>
+    <VerifySourceGeneratorsVersion>2.2.0</VerifySourceGeneratorsVersion>
     <VerifyXunitVersion>19.14.0</VerifyXunitVersion>
     <XunitAbstractionsVersion>2.0.3</XunitAbstractionsVersion>
     <XunitAnalyzersVersion>1.15.0</XunitAnalyzersVersion>

src/OpenApi/OpenApi.slnf

@@ -10,10 +10,12 @@
       "src\\Http\\Http\\src\\Microsoft.AspNetCore.Http.csproj",
       "src\\Http\\Http.Features\\src\\Microsoft.AspNetCore.Http.Features.csproj",
       "src\\Http\\Routing\\src\\Microsoft.AspNetCore.Routing.csproj",
+      "src\\OpenApi\\gen\\Microsoft.AspNetCore.OpenApi.SourceGenerators.csproj",
       "src\\OpenApi\\perf\\Microbenchmarks\\Microsoft.AspNetCore.OpenApi.Microbenchmarks.csproj",
       "src\\OpenApi\\sample\\Sample.csproj",
       "src\\OpenApi\\src\\Microsoft.AspNetCore.OpenApi.csproj",
       "src\\Servers\\Connections.Abstractions\\src\\Microsoft.AspNetCore.Connections.Abstractions.csproj",
+      "src\\OpenApi\\test\\Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests\\Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests.csproj",
       "src\\OpenApi\\test\\Microsoft.AspNetCore.OpenApi.Tests\\Microsoft.AspNetCore.OpenApi.Tests.csproj",
       "src\\OpenApi\\sample\\Sample.csproj",
       "src\\OpenApi\\perf\\Microbenchmarks\\Microsoft.AspNetCore.OpenApi.Microbenchmarks.csproj"

src/OpenApi/build/Microsoft.AspNetCore.OpenApi.targets

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8" standalone="no"?>
+<Project>
+  <PropertyGroup>
+    <InterceptorsNamespaces>$(InterceptorsNamespaces);Microsoft.AspNetCore.OpenApi.Generated</InterceptorsNamespaces>
+    <InterceptorsPreviewNamespaces>
+      $(InterceptorsPreviewNamespaces);Microsoft.AspNetCore.OpenApi.Generated</InterceptorsPreviewNamespaces>
+  </PropertyGroup>
+  <Target Name="GenerateAdditionalXmlFilesForOpenApi"
+    AfterTargets="ResolveReferences">
+    <ItemGroup>
+      <AdditionalFiles
+        Include="@(ReferencePath->'%(RootDir)%(Directory)%(Filename).xml')"
+        Condition="'%(ReferencePath.Extension)' == '.dll' AND
+        Exists('%(ReferencePath.RootDir)%(ReferencePath.Directory)%(ReferencePath.Filename).xml') AND
+        ('%(ReferencePath.ReferenceSourceTarget)' == 'ProjectReference' OR
+         '%(ReferencePath.NuGetSourceType)' == 'Package')"
+         KeepMetadata="Identity" />
+    </ItemGroup>
+  </Target>
+</Project>

src/OpenApi/gen/Helpers/AddOpenApiInvocation.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace Microsoft.AspNetCore.OpenApi.SourceGenerators;
+
+/// <summary>
+/// Represents an invocation of the AddOpenApi method.
+/// </summary>
+/// <param name="Variant">The variant of the AddOpenApi method.</param>
+/// <param name="InvocationExpression">The invocation expression.</param>
+/// <param name="Location">The location of the invocation that can be intercepted.</param>
+internal sealed record AddOpenApiInvocation(
+    AddOpenApiOverloadVariant Variant,
+    InvocationExpressionSyntax InvocationExpression,
+    InterceptableLocation? Location);

src/OpenApi/gen/Helpers/AddOpenApiInvocationComparer.cs

@@ -0,0 +1,27 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.OpenApi.SourceGenerators;
+
+internal class AddOpenApiInvocationComparer : IEqualityComparer<AddOpenApiInvocation>
+{
+    public static AddOpenApiInvocationComparer Instance { get; } = new();
+    public bool Equals(AddOpenApiInvocation? x, AddOpenApiInvocation? y)
+    {
+        if (ReferenceEquals(x, y))
+        {
+            return true;
+        }
+        if (x is null || y is null)
+        {
+            return false;
+        }
+
+        return x.Variant.Equals(y.Variant);
+    }
+
+    public int GetHashCode(AddOpenApiInvocation obj) =>
+        HashCode.Combine(obj.Variant);
+}

src/OpenApi/gen/Helpers/AddOpenApiOverloadVariant.cs

@@ -0,0 +1,13 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.OpenApi.SourceGenerators;
+
+internal enum AddOpenApiOverloadVariant
+{
+    AddOpenApi,
+    AddOpenApiDocumentName,
+    AddOpenApiDocumentNameConfigureOptions,
+    AddOpenApiConfigureOptions,
+    Unknown
+}

src/OpenApi/gen/Helpers/AssemblyTypeSymbolsVisitor.cs

@@ -0,0 +1,82 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Threading;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.AspNetCore.OpenApi.SourceGenerators;
+
+/// <summary>
+/// Visits the assembly symbols to collect public types, properties, and methods that might
+/// contain XML documentation comments.
+/// </summary>
+internal sealed class AssemblyTypeSymbolsVisitor(IAssemblySymbol assemblySymbol, CancellationToken cancellation) : SymbolVisitor
+{
+    private readonly CancellationToken _cancellationToken = cancellation;
+    private readonly HashSet<INamedTypeSymbol> _exportedTypes = new(SymbolEqualityComparer.Default);
+    private readonly HashSet<IPropertySymbol> _exportedProperties = new(SymbolEqualityComparer.Default);
+    private readonly HashSet<IMethodSymbol> _exportedMethods = new(SymbolEqualityComparer.Default);
+
+    public ImmutableArray<INamedTypeSymbol> GetPublicTypes() => [.. _exportedTypes];
+    public ImmutableArray<IPropertySymbol> GetPublicProperties() => [.. _exportedProperties];
+    public ImmutableArray<IMethodSymbol> GetPublicMethods() => [.. _exportedMethods];
+
+    public void VisitAssembly() => VisitAssembly(assemblySymbol);
+
+    public override void VisitAssembly(IAssemblySymbol symbol)
+    {
+        _cancellationToken.ThrowIfCancellationRequested();
+        symbol.GlobalNamespace.Accept(this);
+    }
+
+    public override void VisitNamespace(INamespaceSymbol symbol)
+    {
+        foreach (var namespaceOrType in symbol.GetMembers())
+        {
+            _cancellationToken.ThrowIfCancellationRequested();
+            namespaceOrType.Accept(this);
+        }
+    }
+
+    public override void VisitNamedType(INamedTypeSymbol type)
+    {
+        _cancellationToken.ThrowIfCancellationRequested();
+
+        if (!IsDeclaredInAssembly(type) || !_exportedTypes.Add(type))
+        {
+            return;
+        }
+
+        var nestedTypes = type.GetTypeMembers();
+
+        foreach (var nestedType in nestedTypes)
+        {
+            _cancellationToken.ThrowIfCancellationRequested();
+            nestedType.Accept(this);
+        }
+
+        var properties = type.GetMembers().OfType<IPropertySymbol>();
+        foreach (var property in properties)
+        {
+            _cancellationToken.ThrowIfCancellationRequested();
+            if (IsDeclaredInAssembly(property) && _exportedProperties.Add(property))
+            {
+                property.Type.Accept(this);
+            }
+        }
+        var methods = type.GetMembers().OfType<IMethodSymbol>();
+        foreach (var method in methods)
+        {
+            _cancellationToken.ThrowIfCancellationRequested();
+            if (IsDeclaredInAssembly(method) && _exportedMethods.Add(method))
+            {
+                method.Accept(this);
+            }
+        }
+    }
+
+    private bool IsDeclaredInAssembly(ISymbol symbol) =>
+        SymbolEqualityComparer.Default.Equals(symbol.ContainingAssembly, assemblySymbol);
+}

src/OpenApi/gen/Helpers/DocumentationCommentXmlNames.cs

@@ -0,0 +1,61 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.AspNetCore.OpenApi.SourceGenerators.Xml;
+
+internal static class DocumentationCommentXmlNames
+{
+    public const string CElementName = "c";
+    public const string CodeElementName = "code";
+    public const string CompletionListElementName = "completionlist";
+    public const string DescriptionElementName = "description";
+    public const string ExampleElementName = "example";
+    public const string ExceptionElementName = "exception";
+    public const string IncludeElementName = "include";
+    public const string InheritdocElementName = "inheritdoc";
+    public const string ItemElementName = "item";
+    public const string ListElementName = "list";
+    public const string ListHeaderElementName = "listheader";
+    public const string ParaElementName = "para";
+    public const string ParameterElementName = "param";
+    public const string ParameterReferenceElementName = "paramref";
+    public const string PermissionElementName = "permission";
+    public const string PlaceholderElementName = "placeholder";
+    public const string PreliminaryElementName = "preliminary";
+    public const string RemarksElementName = "remarks";
+    public const string ReturnsElementName = "returns";
+    public const string SeeElementName = "see";
+    public const string SeeAlsoElementName = "seealso";
+    public const string SummaryElementName = "summary";
+    public const string TermElementName = "term";
+    public const string ThreadSafetyElementName = "threadsafety";
+    public const string TypeParameterElementName = "typeparam";
+    public const string TypeParameterReferenceElementName = "typeparamref";
+    public const string ValueElementName = "value";
+    public const string CrefAttributeName = "cref";
+    public const string HrefAttributeName = "href";
+    public const string FileAttributeName = "file";
+    public const string InstanceAttributeName = "instance";
+    public const string LangwordAttributeName = "langword";
+    public const string NameAttributeName = "name";
+    public const string PathAttributeName = "path";
+    public const string StaticAttributeName = "static";
+    public const string TypeAttributeName = "type";
+
+    public static bool ElementEquals(string name1, string name2, bool fromVb = false)
+    {
+        return string.Equals(name1, name2, fromVb ? StringComparison.Ordinal : StringComparison.OrdinalIgnoreCase);
+    }
+
+    public static bool AttributeEquals(string name1, string name2)
+    {
+        return string.Equals(name1, name2, StringComparison.Ordinal);
+    }
+
+    public static new bool Equals(object left, object right)
+    {
+        return object.Equals(left, right);
+    }
+}