Adding a bridge that needs final_touch bridges in the final_touch of another bridge

[blegat]

If a bridge adds a constraint that needs a bridge that need_final_touch then it will modify the needs_final_touch being iterated over

MathOptInterface.jl/src/Bridges/Constraint/map.jl

Lines 321 to 334 in 95a73a0

	# Function barrier to iterate over bridges of the same type in an efficient way.
	function _final_touch(bridges, model)
	for bridge in bridges
	MOI.Bridges.final_touch(bridge, model)
	end
	return
	end
	function MOI.Bridges.final_touch(map::Map, model::MOI.ModelLike)
	for bridges in values(map.needs_final_touch)
	_final_touch(bridges, model)
	end
	return
	end

In that case, we might not call final_touch on that bridge.

[odow]

Is there an example of this?

[odow]

So we nearly had an example of this with #2316. I started to add SOSToMILP but then the IndicatorToSOS bridge would enable Indicator to MILP, except that IndicatorToSOS does not add variable bounds, so it would error.

To fix, we'd need a final_touch in IndicatorToSOS to update the final bounds on the slack variable, and then the usual final touch in SOSToMILP. So we'd have to touch IndicatorToSOS before touching SOSToMILP.

This will require a DAG of final_touch rather than the Set that we currently use, but it might be sufficient to just use a vector ordered by creation date?