Re: [PATCH] Suppress warning in rust-ast-lower-type.h ASTLowerGenericParam.visit.

[Mark Wielaard <mark@klomp.org>]

On Tue, Jun 29, 2021 at 12:47:07AM +0200, Mark Wielaard wrote:
> On Tue, Jun 29, 2021 at 12:06:56AM +0200, Marc wrote:
> > Hi,
> > 
> > > Translating the AST LifetimeType to the HIR LifetimeType causes a warning:
> > > warning: ‘ltt’ may be used uninitialized
> > 
> > Was wondering why this is needed as the switch case covers all enum
> > variants, how can ltt be uninitialized ? I have the same fix locally but
> > was thinking something else was causing the error...
> 
> LifetimeType is a plain enum, which aren't really their own types,
> they are really just ints with fancy names. We could make them enum
> class, which is a strong type. Then the compiler would know the switch
> really covers all enum (class) variants. But then we have to provide
> the right scope/type everywhere we use them in the code (which might
> be a good idea, but is more typing).

I just tried to make LifetimeType an enum class and that doesn't help.
So I was wrong. I don't know why the compiler doesn't see this? It
should know since if not all switch cases were covered, -Wswitch
(enabled by -Wall) gives us a warning... So, I don't fully understand
why gcc needs the default gcc_unreachable case. It is what is used in
the rest of the code though.

Cheers,

Mark