Proposal: noreturn methods

[omariom]

TypeScript got never type which allows to define methods that never return.
I propose similar feature for C#.

Methods "returning" noreturn type must definitely throw or call other noreturn methods.
They can't have return statements in their body nor out parameters. At callsites they should be threated by the compiler similarly to throw statements.

It will require support from CLR. and that's a good thing as CLR could take advantage of that and optimize generated code around callsites to noreturns as it does now with throws.

private noreturn LogAndFailFast()
{
     s_logger.Log(whatever_required);
     Environment.FailFast();
}

static class ThrowHelper
{
   public noreturn ThrowInvalidInputException(ObjectType type, long id)
   {
       throw new InvalidInputException(string.Format(InvalidInputFormatString, type, id));
   }
}

[omariom]

@mikedn I remember you talked about benefits of noreturns for codegen.

[HaloFour]

Dupe of #1226

[omariom]

Ouch!