C406 false positive

[adamchainz]

With something assigned to a two-tuple,dict([something]) incorrectly gets marked by C406 as something that can be converted to a dict literal.

[tolomea]

I think it can only be turned into a dict literal when every element in the list is either a two-tuple or a two-list

[tolomea]

although lists and tuples of other lengths would explode in the dict constructor, so when every element is either a tuple or list should be sufficient

[graingert]

dict([something]) # ok
dict([[]]) # bad
dict([()]) # bad
dict([("foo", "bar"), something]) # bad prefer -> {"foo": "bar"} | dict([something])
dict([{"foo", "bar"}] # bad (key-value lottery)
dict([{"foo": None, "bar": None}] # bad
dict([tuple((1, 2))]) # bad
dict([list((1, 2))]) #bad

[graingert]

although, for the original case, I prefer to use

k, v = something
mapping = {k: v}

so perhaps it should be moved to a different error code, with a suggestion to unpack and use a dict literal