Re: Diagnostic improvements in 1.78/1.79

From: Gavin Lambert (boost_at_[hidden])
Date: 2022-02-15 02:28:42

On 15/02/2022 15:11, Emil Dotchevski wrote:
> In terms of the latter, Gavin quite literally describes Boost LEAF. It is
> indeed possible for "Boost-aware" throws to automatically detect what info
> is actually needed for error handling, and only spend cycles capturing
> that. This is exactly how leaf::on_error works.

Not quite.  LEAF works explicitly through TLS rather than the local 
stack, which makes it less compatible with coroutines, AFAIK.

Granted that the mechanism I proposed would probably not be 
implementable without a TLS root to register with or something; while 
the context objects themselves would naturally be coroutine-compatible, 
a way to actually *find* which ones are still in scope in a particular 
context is harder to manage without making those sorts of assumptions.

Unfortunately C++ lacks execution-context-ambient state that would work 
in either scenario.