[SourceGen] Add support for overriding binding property name

sdk/Sdk.Generators/Constants.cs

@@ -11,6 +11,7 @@ internal static class Constants
         internal const string FunctionNameType = "Microsoft.Azure.Functions.Worker.FunctionAttribute";
         internal const string HttpResponseType = "Microsoft.Azure.Functions.Worker.Http.HttpResponseData";
         internal const string EventHubsTriggerType = "Microsoft.Azure.Functions.Worker.EventHubTriggerAttribute";
+        internal const string BindingPropertyNameAttributeType = "Microsoft.Azure.Functions.Worker.Extensions.Abstractions.BindingPropertyNameAttribute";
 
         // System types
         internal const string IEnumerableType = "System.Collections.IEnumerable";

sdk/Sdk.Generators/FunctionMetadataProviderGenerator.Parser.cs

@@ -535,7 +535,9 @@ private bool TryLoadConstructorArguments(AttributeData attributeData, IDictionar
                 // that the constructor names would match the property names
                 for (int i = 0; i < attributeData.ConstructorArguments.Length; i++)
                 {
-                    var argumentName = attribMethodSymbol.Parameters[i].Name;
+                    string argumentName = attribMethodSymbol.Parameters[i].Name;
+                    OverrideBindingName(attributeData.AttributeClass!, ref argumentName); // either argumentName will remain unchanged OR be updated to the overridden name at the end of this.
+
                     var arg = attributeData.ConstructorArguments[i];
 
                     switch (arg.Kind)
@@ -562,6 +564,24 @@ private bool TryLoadConstructorArguments(AttributeData attributeData, IDictionar
                 return true;
             }
 
+            private void OverrideBindingName(INamedTypeSymbol attributeClass, ref string argumentName)
+            {
+                var bindingPropertyNameSymbol = Compilation.GetTypeByMetadataName(Constants.BindingPropertyNameAttributeType);
+
+                foreach (var prop in attributeClass.GetMembers().Where(a => a is IPropertySymbol))
+                {
+                    if (String.Equals(prop.Name, argumentName, StringComparison.OrdinalIgnoreCase)) // relies on convention where constructor parameter names match the property their value will be assigned to (JSON serialization is a precedence for this convention)
+                    {
+                        var bindingNameAttrList = prop.GetAttributes().Where(attr => SymbolEqualityComparer.Default.Equals(attr.AttributeClass, bindingPropertyNameSymbol));
+
+                        if (bindingNameAttrList.SingleOrDefault() is { } bindingNameAttr) // there will only be one BindingAttributeName attribute b/c there can't be duplicate attributes on a piece of syntax
+                        {
+                            argumentName = bindingNameAttr.ConstructorArguments.First().Value!.ToString(); // there is only one constructor argument for this binding attribute (the binding name override)
+                        }
+                    }
+                }
+            }
+
             /// <summary>
             /// This method verifies that an EventHubsTrigger matches our expectations on cardinality (isBatched property). If isBatched is set to true, the parameter with the
             /// attribute must be an enumerable type.

test/Sdk.Generator.Tests/FunctionMetadataProviderGeneratorTests/StorageBindingTests.cs

@@ -236,7 +236,7 @@ public Task<ImmutableArray<IFunctionMetadata>> GetFunctionMetadataAsync(string d
                 name = 'blob',
                 type = 'BlobTrigger',
                 direction = 'In',
-                blobPath = 'container2/%file%',
+                path = 'container2/%file%',
                 dataType = 'String',
             };
             var Function1binding1JSON = JsonSerializer.Serialize(Function1binding1);