Add generics_of to smir

[ouz-a]

Continuing our covering of smir.

r? @spastorino

[rustbot]

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This PR changes Stable MIR

cc @oli-obk, @celinval, @spastorino

[spastorino]

I'd implement this more like:

    fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
        use stable_mir::ty::Generics;

        let params: Vec<_> = self.params.iter().map(|param| {
            param.stable(tables)
        }).collect();
        let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();

        Generics {
            parent: self.parent.map(|did| tables.generic_def(did)),
            parent_count: self.parent_count,
            params,
            param_def_id_to_index,
            has_self: self.has_self,
            has_late_bound_regions: self.has_late_bound_regions.as_ref().map(|late_bound_regions| late_bound_regions.stable(tables)),
            host_effect_index: self.host_effect_index,
        }
    }

Then you can remove FxHashMap requirement, remove the rustc::potential_query_instability attribute and the dependency of rustc_data_structures. Would need to implement stable for Span and would need GenericDef to be Copy, just make all these Defs copy. Otherwise just call opaque directly for now.

[spastorino]

@bors r+ rollup

[bors]

📌 Commit 015b5cb has been approved by spastorino

It is now in the queue for this repository.