Improve configuration parameter type compatibility checks in python

[makortel]

This issue is a follow-up to discussion in #41349 (comment)

Currently assignment like

process.options.numberOfThreads = cms.untracked.int32(4)

override the type of the existing parameter of a PSet. In most cases the incorrect type gets caught by the C++ code (in case of #32070 it wasn't caught, which is fixed in #41349). It would be generally beneficial to be able catch such inconsistencies already earlier in python.

For regular cms.X types @Dr15Jones came with three options

1. do an implicit type conversion. I.e. if the value in the ‘wrong’ type is convertible to the ‘right’ type, do the conversion quietly
2. check for compatibility when assigning to ‘special’ types, i.e. if assigning to optional, required or allowed enforce that the type is proper
3. require ALL types match. If one wants to ‘change’ a type they must first do a del pset.name to get rid of it
   • or we could add new override proxy type, making intentional type changes to look like p.a = cms.override.int32(4)

Since the PSet assignment is really handled by PSet.__setattr__(), the necessary changes would need to go there, more specifically to

cmssw/FWCore/ParameterSet/python/Mixins.py

Lines 278 to 282 in 107dcfb

	# handle the case where users just replace with a value, a = 12, rather than a = cms.int32(12)
	if isinstance(value,_ParameterTypeBase):
	self.__dict__[name] = value
	else:
	self.__dict__[name].setValue(value)

[makortel]

assign core

[cmsbuild]

New categories assigned: core

@Dr15Jones,@smuzaffar,@makortel you have been requested to review this Pull request/Issue and eventually sign? Thanks

[cmsbuild]

A new Issue was created by @makortel Matti Kortelainen.

@Dr15Jones, @perrotta, @dpiparo, @rappoccio, @makortel, @smuzaffar can you please review it and eventually sign/assign? Thanks.

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[makortel]

The improvements were done in #41361

[makortel]

+core

[cmsbuild]

This issue is fully signed and ready to be closed.