Description

Inconsistent type argument constraints in the StartNewAsync<T> method, resulting in compilation errors depending on the method overload actually used.

The method with two arguments has a class constraint, but the one with three arguments does not. As a result, the method with two arguments causes an error if the tuple type is used.

The generic type argument for StartNewAsync<T> may not be necessary. There is no generic method for sub-orchestrators, so it is inconsistent to have a generic method only for StartNewAsync<T>.

Expected behavior

Can be compiled successfully with Tuple.

Actual behavior

A compile error occurs.

Relevant source code snippets

// error CS7036: There is no argument given that corresponds to the required formal parameter 'input' of 'IDurableOrchestrationClient.StartNewAsync<T>(string, string, T)
string instanceId = await starter.StartNewAsync("Function1", ("test", 1, 2, 3));

Known workarounds

// 1. Specify the type argument explicitly
string instanceId = await starter.StartNewAsync<object>("Function1", ("test", 1, 2, 3));

// 2. Use an overload method with three arguments
string instanceId = await starter.StartNewAsync("Function1", null, ("test", 1, 2, 3));

App Details

• Durable Functions extension version (e.g. v1.8.3): 2.4.3
• Azure Functions runtime version (1.0 or 2.0): 3.0
• Programming language used: C#