Function check_explicit_clauses 

fn check_explicit_clauses<'tcx>(
    tcx: TyCtxt<'tcx>,
    def_id: DefId,
    args: &[GenericArg<'tcx>],
    required_clauses: &mut FxIndexMap<ArgOutlivesClause<'tcx>, Span>,
    explicit_map: &mut ExplicitClausesMap<'tcx>,
    ignore_clauses_refing_self: IgnoreClausesReferencingSelf,
)

Check the explicit clauses declared on the type.

Example

struct Outer<'a, T> {
    field: Inner<T>,
}

struct Inner<U> where U: 'static, U: Outer {
    // ...
}

Here, we should fetch the explicit clauses, which will give us U: 'static and U: Outer. The latter we can ignore, but we will want to process U: 'static, applying the instantiation as above.