MIR const-prop not putting usize into AggregateKind::RawPtr?

        _18 = const 128_usize;
        StorageLive(_24);
        _24 = _22 as *const () (PtrToPtr);
        _23 = *const [u8] from (_24, _18);

Because I would have expected constprop into the Aggregate, like

        StorageLive(_24);
        _24 = _22 as *const () (PtrToPtr);
        _23 = *const [u8] from (_24, const 128_usize);

As happened in other places, like

        _20 = Offset(_16, const 128_usize);
        StorageLive(_21);
        _21 = Sub(_13, const 128_usize);

AggregateKind::RawPtr is relatively new (#123840), so maybe it needs to be handled properly somewhere else?

I think the problem is this FIXME that you added:

Lines 930 to 931 in 8b64adc

    
           // FIXME: Do the extra work to GVN `from_raw_parts` 
        
           AggregateKind::RawPtr(..) => return None,

Constant propagation is done by GVN.

@saethlin

Foiled once again by my greatest nemesis: my past self.

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	// FIXME: Do the extra work to GVN `from_raw_parts`
	AggregateKind::RawPtr(..) => return None,