Support mapping <returns> to response description

src/OpenApi/gen/XmlCommentGenerator.Emitter.cs

@@ -372,6 +372,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/OperationTests.MinimalApis.cs

@@ -55,6 +55,7 @@ public static class RouteHandlerExtensionMethods
     /// <description>
     /// A description of the action.
     /// </description>
+    /// <returns>Returns the greeting.</returns>
     public static string Get()
     {
         return "Hello, World!";
@@ -68,17 +69,20 @@ public static string Get2(string name)
     }
 
     /// <param name="name" example="Testy McTester">The name of the person.</param>
+    /// <returns>Returns the greeting.</returns>
+    /// <returns>Returns a different greeting.</returns>
     public static string Get3(string name)
     {
         return $"Hello, {name}!";
     }
 
-    /// <response code="404">Indicates that the value was not found.</response>
+    /// <returns>Indicates that the value was not found.</returns>
     public static NotFound<string> Get4()
     {
         return TypedResults.NotFound("Not found!");
     }
 
+    /// <returns>This gets ignored.</returns>
     /// <response code="200">Indicates that the value is even.</response>
     /// <response code="201">Indicates that the value is less than 50.</response>
     /// <response code="404">Indicates that the value was not found.</response>
@@ -174,6 +178,7 @@ public static ValueTask<string> Get13()
     /// <summary>
     /// A summary of Get14.
     /// </summary>
+    /// <returns>Returns the greeting.</returns>
     public static async Task<Holder<string>> Get14()
     {
         await Task.Delay(1000);
@@ -182,6 +187,7 @@ public static async Task<Holder<string>> Get14()
     /// <summary>
     /// A summary of Get15.
     /// </summary>
+    /// <response code="200">Returns the greeting.</response>
     public static Task<Holder<string>> Get15()
     {
         return Task.FromResult(new Holder<string> { Value = "Hello, World!" });
@@ -234,6 +240,7 @@ await SnapshotTestHelper.VerifyOpenApi(compilation, document =>
             var path = document.Paths["/1"].Operations[HttpMethod.Get];
             Assert.Equal("A summary of the action.", path.Summary);
             Assert.Equal("A description of the action.", path.Description);
+            Assert.Equal("Returns the greeting.", path.Responses["200"].Description);
 
             var path2 = document.Paths["/2"].Operations[HttpMethod.Get];
             Assert.Equal("The name of the person.", path2.Parameters[0].Description);
@@ -243,6 +250,7 @@ await SnapshotTestHelper.VerifyOpenApi(compilation, document =>
             Assert.Equal("The name of the person.", path3.Parameters[0].Description);
             var example = Assert.IsAssignableFrom<JsonNode>(path3.Parameters[0].Example);
             Assert.Equal("\"Testy McTester\"", example.ToJsonString());
+            Assert.Equal("Returns the greeting.", path3.Responses["200"].Description);
 
             var path4 = document.Paths["/4"].Operations[HttpMethod.Get];
             var response = path4.Responses["404"];
@@ -285,9 +293,11 @@ await SnapshotTestHelper.VerifyOpenApi(compilation, document =>
 
             var path14 = document.Paths["/14"].Operations[HttpMethod.Get];
             Assert.Equal("A summary of Get14.", path14.Summary);
+            Assert.Equal("Returns the greeting.", path14.Responses["200"].Description);
 
             var path15 = document.Paths["/15"].Operations[HttpMethod.Get];
             Assert.Equal("A summary of Get15.", path15.Summary);
+            Assert.Equal("Returns the greeting.", path15.Responses["200"].Description);
 
             var path16 = document.Paths["/16"].Operations[HttpMethod.Post];
             Assert.Equal("A summary of Post16.", path16.Summary);

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/AddOpenApiTests.CanInterceptAddOpenApi#OpenApiXmlCommentSupport.generated.verified.cs

@@ -354,6 +354,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/AdditionalTextsTests.CanHandleXmlForSchemasInAdditionalTexts#OpenApiXmlCommentSupport.generated.verified.cs

@@ -383,6 +383,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/CompletenessTests.SupportsAllXmlTagsOnSchemas#OpenApiXmlCommentSupport.generated.verified.cs

@@ -473,6 +473,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/OperationTests.SupportsXmlCommentsOnOperationsFromControllers#OpenApiXmlCommentSupport.generated.verified.cs

@@ -358,6 +358,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/OperationTests.SupportsXmlCommentsOnOperationsFromMinimalApis#OpenApiXmlCommentSupport.generated.verified.cs

@@ -73,11 +73,11 @@ private static Dictionary<string, XmlComment> GenerateCacheEntries()
         {
             var cache = new Dictionary<string, XmlComment>();
 
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get~System.String", new XmlComment(@"A summary of the action.", @"A description of the action.", null, null, null, false, null, null, null));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get~System.String", new XmlComment(@"A summary of the action.", @"A description of the action.", null, @"Returns the greeting.", null, false, null, null, null));
             cache.Add(@"M:RouteHandlerExtensionMethods.Get2(System.String)~System.String", new XmlComment(null, null, null, null, null, false, null, [new XmlParameterComment(@"name", @"The name of the person.", null, false)], [new XmlResponseComment(@"200", @"Returns the greeting.", @"")]));
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get3(System.String)~System.String", new XmlComment(null, null, null, null, null, false, null, [new XmlParameterComment(@"name", @"The name of the person.", @"Testy McTester", false)], null));
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get4~Microsoft.AspNetCore.Http.HttpResults.NotFound{System.String}", new XmlComment(null, null, null, null, null, false, null, null, [new XmlResponseComment(@"404", @"Indicates that the value was not found.", @"")]));
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get5~Microsoft.AspNetCore.Http.HttpResults.Results{Microsoft.AspNetCore.Http.HttpResults.NotFound{System.String},Microsoft.AspNetCore.Http.HttpResults.Ok{System.String},Microsoft.AspNetCore.Http.HttpResults.Created}", new XmlComment(null, null, null, null, null, false, null, null, [new XmlResponseComment(@"200", @"Indicates that the value is even.", @""), new XmlResponseComment(@"201", @"Indicates that the value is less than 50.", @""), new XmlResponseComment(@"404", @"Indicates that the value was not found.", @"")]));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get3(System.String)~System.String", new XmlComment(null, null, null, @"Returns the greeting.", null, false, null, [new XmlParameterComment(@"name", @"The name of the person.", @"Testy McTester", false)], null));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get4~Microsoft.AspNetCore.Http.HttpResults.NotFound{System.String}", new XmlComment(null, null, null, @"Indicates that the value was not found.", null, false, null, null, null));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get5~Microsoft.AspNetCore.Http.HttpResults.Results{Microsoft.AspNetCore.Http.HttpResults.NotFound{System.String},Microsoft.AspNetCore.Http.HttpResults.Ok{System.String},Microsoft.AspNetCore.Http.HttpResults.Created}", new XmlComment(null, null, null, @"This gets ignored.", null, false, null, null, [new XmlResponseComment(@"200", @"Indicates that the value is even.", @""), new XmlResponseComment(@"201", @"Indicates that the value is less than 50.", @""), new XmlResponseComment(@"404", @"Indicates that the value was not found.", @"")]));
             cache.Add(@"M:RouteHandlerExtensionMethods.Post6(User)~Microsoft.AspNetCore.Http.IResult", new XmlComment(@"Creates a new user.", null, @"Sample request:
     POST /6
     {
@@ -91,8 +91,8 @@ private static Dictionary<string, XmlComment> GenerateCacheEntries()
             cache.Add(@"M:RouteHandlerExtensionMethods.Get11~System.Threading.Tasks.ValueTask", new XmlComment(@"A summary of Get11.", null, null, null, null, false, null, null, null));
             cache.Add(@"M:RouteHandlerExtensionMethods.Get12~System.Threading.Tasks.Task{System.String}", new XmlComment(@"A summary of Get12.", null, null, null, null, false, null, null, null));
             cache.Add(@"M:RouteHandlerExtensionMethods.Get13~System.Threading.Tasks.ValueTask{System.String}", new XmlComment(@"A summary of Get13.", null, null, null, null, false, null, null, null));
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get14~System.Threading.Tasks.Task{Holder{System.String}}", new XmlComment(@"A summary of Get14.", null, null, null, null, false, null, null, null));
-            cache.Add(@"M:RouteHandlerExtensionMethods.Get15~System.Threading.Tasks.Task{Holder{System.String}}", new XmlComment(@"A summary of Get15.", null, null, null, null, false, null, null, null));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get14~System.Threading.Tasks.Task{Holder{System.String}}", new XmlComment(@"A summary of Get14.", null, null, @"Returns the greeting.", null, false, null, null, null));
+            cache.Add(@"M:RouteHandlerExtensionMethods.Get15~System.Threading.Tasks.Task{Holder{System.String}}", new XmlComment(@"A summary of Get15.", null, null, null, null, false, null, null, [new XmlResponseComment(@"200", @"Returns the greeting.", @"")]));
             cache.Add(@"M:RouteHandlerExtensionMethods.Post16(Example)", new XmlComment(@"A summary of Post16.", null, null, null, null, false, null, null, null));
             cache.Add(@"M:RouteHandlerExtensionMethods.Get17(System.Int32[])~System.Int32[][]", new XmlComment(@"A summary of Get17.", null, null, null, null, false, null, null, null));
 
@@ -376,6 +376,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/SchemaTests.SupportsXmlCommentsOnSchemas#OpenApiXmlCommentSupport.generated.verified.cs

@@ -384,6 +384,13 @@ public Task TransformAsync(OpenApiOperation operation, OpenApiOperationTransform
                         }
                     }
                 }
+                // Applies `<returns>` on XML comments for operation with single response value.
+                if (methodComment.Returns is { } returns && operation.Responses is { Count: 1 })
+                {
+                    var response = operation.Responses.First();
+                    response.Value.Description = returns;
+                }
+                // Applies `<response>` on XML comments for operation with multiple response values.
                 if (methodComment.Responses is { Count: > 0} && operation.Responses is { Count: > 0 })
                 {
                     foreach (var response in operation.Responses)