Suggestion: Relax CS0748 for lambdas receiving a ref/out parameter

[Joe4evr]

This is quite minor, but I'd like to throw it out there for discussion and consideration.

Suppose you have a delegate that receives a parameter by ref/out:

public delegate void RefAction<T, TState>(ref T obj, TState state);

// API method:
public void M<TState>(RefAction<Foo, TState> action, TState state);

Currently, writing a lambda of this signature requires writing out the full parameter list.

M((ref Foo foo, Bar bar) => { ... }, someBar);

It'd be much nicer (and more intuitive) if the ref can be applied while still having the parameters implicitly typed:

// Currently yields 'CS0748: Inconsistent lambda parameter usage; parameter types must be all explicit or all implicit'
M((ref foo, bar) => { ... }, someBar);

[svick]

This is a duplicate of #338.

[Joe4evr]

Okay, this is why such suggestions should list the error number because that's what I searched on before opening. 🙄