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Date: Thu, 25 Nov 2021 13:59:41 +0000 (UTC)
From: Michael Matz <matz@suse.de>
To: Richard Biener <rguenther@suse.de>
cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] Remove unreachable gcc_unreachable () at the end of
 functions
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Hello,

On Thu, 25 Nov 2021, Richard Biener via Gcc-patches wrote:

> It seems to be a style to place gcc_unreachable () after a
> switch that handles all cases with every case returning.
> Those are unreachable (well, yes!), so they will be elided
> at CFG construction time and the middle-end will place
> another __builtin_unreachable "after" them to note the
> path doesn't lead to a return when the function is not declared
> void.
> 
> So IMHO those explicit gcc_unreachable () serve no purpose,
> if they could be replaced by a comment.

Never document in comments what you can document in code (IMO).  I think 
the code as-is clearly documents the invariants and expectations and 
removing the gcc_unreachable() leads to worse sources.

Can't you simply exempt warning on unreachable __builtin_unreachable()?
It seems an obvious thing that the warning should _not_ warn about, after 
all, quite clearly, the author is aware of that being unreachable, it says 
so, right there.


Ciao,
Michael.