Dialyzer errors with if/then

[timothyvanderaerden]

I have a schema with a required value based on the value of an enum, the schema looks likt the following:

"type": "object",
"required": [
    "a"
],
"additionalProperties": false,
"properties": {
    "a": {
        "type": "string",
        "enum": [
            "one",
            "two"
        ]
    },
    "b": {
        "type": "string"
    }
},
"allOf": [
    {
        "if": {
            "properties": {
                "a": {
                    "const": "one"
                }
            }
        },
        "then": {
            "required": [
                "b"
            ]
        }
    }
]

Dialyzer will output the following error:

lib/json_schema.ex:44:pattern_match_cov
The pattern
_, _

can never match, because previous clauses completely cover the type
map(), <<_::8>>.

________________________________________________________________________________
lib/json_schema.ex:57:guard_fail
The guard test:

is_boolean(_ :: map())

can never succeed.

________________________________________________________________________________
lib/json_schema.ex:57:guard_fail
The guard test:

is_float(_ :: map())

can never succeed.

________________________________________________________________________________
lib/json_schema.ex:57:guard_fail
The guard test:

is_integer(_ :: map())

can never succeed.

________________________________________________________________________________
lib/json_schema.ex:57:guard_fail
The guard test:

is_list(_ :: map())

can never succeed.

________________________________________________________________________________
lib/json_schema.ex:57:guard_fail
The guard clause:

when _ :: map() == nil

can never succeed.

________________________________________________________________________________
done (warnings were emitted)
Halting VM with exit status 2