Hi Marc,
On Tue, Jun 29, 2021 at 08:28:51AM +0200, Marc wrote:
> Mark Wielaard <[email protected]> writes:
> > 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.
>
> I thought maybe that's a C++ vs C diff, or something caused by the
> Lifetime being returned by a function call, but I can't reproduce it, so
> that must be something else:
>
> https://godbolt.org/z/sjbcWEqdj
Try using the result of the function and using -O2
enum LifetimeType
{
NAMED, // corresponds to LIFETIME_OR_LABEL
STATIC, // corresponds to 'static
WILDCARD // corresponds to '_
};
int g(int i);
LifetimeType toto();
int t () {
int t;
switch(toto()){
case NAMED:
t=4;
break;
case STATIC:
t=5;
break;
case WILDCARD:
t=8;
break;
}
return g(t);
}
gcc -O2 -Wall
<source>: In function 'int t()':
<source>:24:15: warning: 't' may be used uninitialized in this function
[-Wmaybe-uninitialized]
24 | return g(t);
| ~^~~
> Anyway, Philipp wants to have these enum shared between AST and HIR, so
> this kind of 'if(AST::Foo) t=HIR::Foo' can be removed.
That might be a good idea if the LifetimeType has the same values and
semantics between AST and HIR.
But till that happend I think it is a good idea to suppress warnings like this.
Cheers,
Mark
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