Recompute the XmlDocs when method signature is updated (#7240)

Contributes to Azure/azure-sdk-for-net#49632

Author: JoshLove-msft

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Providers/ConstructorProvider.cs

@@ -37,7 +37,7 @@ public ConstructorProvider(ConstructorSignature signature, MethodBodyStatement b
         {
             Signature = signature;
             bool skipParamValidation = !signature.Modifiers.HasFlag(MethodSignatureModifiers.Public);
-            var paramHash = MethodProviderHelpers.GetParamhash(signature.Parameters, skipParamValidation);
+            var paramHash = MethodProviderHelpers.GetParamHash(signature.Parameters, skipParamValidation);
             BodyStatements = MethodProviderHelpers.GetBodyStatementWithValidation(signature.Parameters, bodyStatements, paramHash);
             XmlDocs = xmlDocProvider ?? MethodProviderHelpers.BuildXmlDocs(signature.Parameters, signature.Description, null, paramHash);
             EnclosingType = enclosingType;

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Providers/MethodProvider.cs

@@ -15,7 +15,9 @@ public class MethodProvider
         public MethodSignature Signature { get; private set; }
         public MethodBodyStatement? BodyStatements { get; private set;}
         public ValueExpression? BodyExpression { get; private set;}
-        public XmlDocProvider? XmlDocs { get; private set;}
+
+        public XmlDocProvider? XmlDocs => _xmlDocs ??= BuildXmlDocs();
+        private XmlDocProvider? _xmlDocs;
 
         public TypeProvider EnclosingType { get; }
 
@@ -37,9 +39,9 @@ public MethodProvider(MethodSignature signature, MethodBodyStatement bodyStateme
         {
             Signature = signature;
             bool skipParamValidation = !signature.Modifiers.HasFlag(MethodSignatureModifiers.Public);
-            var paramHash = MethodProviderHelpers.GetParamhash(signature.Parameters, skipParamValidation);
+            var paramHash = MethodProviderHelpers.GetParamHash(signature.Parameters, skipParamValidation);
             BodyStatements = MethodProviderHelpers.GetBodyStatementWithValidation(signature.Parameters, bodyStatements, paramHash);
-            XmlDocs = xmlDocProvider ?? MethodProviderHelpers.BuildXmlDocs(signature.Parameters, signature.Description, signature.ReturnDescription, paramHash);
+            _xmlDocs = xmlDocProvider;
             EnclosingType = enclosingType;
         }
 
@@ -54,10 +56,23 @@ public MethodProvider(MethodSignature signature, ValueExpression bodyExpression,
         {
             Signature = signature;
             BodyExpression = bodyExpression;
-            XmlDocs = xmlDocProvider ?? MethodProviderHelpers.BuildXmlDocs(signature.Parameters, signature.Description, signature.ReturnDescription, null);
+            _xmlDocs = xmlDocProvider;
             EnclosingType = enclosingType;
         }
 
+        private XmlDocProvider? BuildXmlDocs()
+        {
+            return MethodProviderHelpers.BuildXmlDocs(
+                Signature.Parameters,
+                Signature.Description,
+                Signature.ReturnDescription,
+                BodyStatements != null ?
+                    MethodProviderHelpers.GetParamHash(
+                        Signature.Parameters,
+                        !Signature.Modifiers.HasFlag(MethodSignatureModifiers.Public)) :
+                    null);
+        }
+
         public void Update(
             MethodSignature? signature = null,
             MethodBodyStatement? bodyStatements = null,
@@ -67,6 +82,8 @@ public void Update(
             if (signature != null)
             {
                 Signature = signature;
+                // rebuild the XML docs if the signature changes
+                _xmlDocs = BuildXmlDocs();
             }
             if (bodyStatements != null)
             {
@@ -80,7 +97,7 @@ public void Update(
             }
             if (xmlDocProvider != null)
             {
-                XmlDocs = xmlDocProvider;
+                _xmlDocs = xmlDocProvider;
             }
         }
     }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Utilities/MethodProviderHelpers.cs

@@ -12,7 +12,7 @@ namespace Microsoft.TypeSpec.Generator
 {
     internal static class MethodProviderHelpers
     {
-        public static Dictionary<ParameterValidationType, List<ParameterProvider>>? GetParamhash(IEnumerable<ParameterProvider> parameters, bool skipParamValidation)
+        public static Dictionary<ParameterValidationType, List<ParameterProvider>>? GetParamHash(IEnumerable<ParameterProvider> parameters, bool skipParamValidation)
         {
             Dictionary<ParameterValidationType, List<ParameterProvider>>? paramHash = null;
             if (!skipParamValidation)

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/test/Providers/MethodProviderTests.cs

@@ -61,13 +61,26 @@ public void TestUpdate()
             typeProvider.Update(methods: [methodProvider]);
 
             // now update the method and check if the type provider reflects the change
-            methodProvider.Update(new MethodSignature("Updated", $"", MethodSignatureModifiers.Public, null, $"", []));
+            methodProvider.Update(new MethodSignature("Updated", $"", MethodSignatureModifiers.Public, null, $"", [new ParameterProvider("foo", $"Foo description", typeof(int))]));
             var updatedMethods = typeProvider.CanonicalView.Methods;
             Assert.IsNotNull(updatedMethods);
             Assert.AreEqual(1, updatedMethods!.Count);
 
+            // Validate that the method name is updated
             var updatedMethod = updatedMethods[0];
             Assert.AreEqual("Updated", updatedMethod.Signature.Name);
+
+            // Validate that the parameter description is updated
+            var parameter = updatedMethod.Signature.Parameters[0];
+            Assert.AreEqual("Foo description", parameter.Description.ToString());
+            Assert.IsTrue(parameter.Type.Equals(typeof(int)));
+
+            // Validate that the xml docs are updated
+            Assert.IsNotNull(updatedMethod.XmlDocs);
+            var xmlDocParamStatement = updatedMethod.XmlDocs!.Parameters[0];
+            Assert.IsNotNull(xmlDocParamStatement);
+            Assert.AreEqual(parameter, xmlDocParamStatement.Parameter);
+            Assert.AreEqual("/// <param name=\"foo\"> Foo description. </param>\n", xmlDocParamStatement.ToDisplayString());
         }
 
         private class TestTypeProvider : TypeProvider