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Dialyzer warning on pattern match using :atom
I have two function clauses
@spec some_function(integer(), :unavailable) ::
{:ok, User.t()} | {:error, Ecto.Changeset.t()}
def some_function(id, :unavailable) do
@spec some_function(integer(), :waiting | :working) ::
{:ok, User.t()} | {:error, Ecto.Changeset.t()}
def some_function(id, state) do
call this function
SomeModule.some_function(3, :waiting)
This will raise warning from dialyzer.
Is there better way to implement this function? or I can ignore warning?
First Post!
al2o3cr
Most Liked
gpopides
the warning probably is about defining twice the spec. Use 1 spec for both functions
@spec some_function(integer(), :unavailable | :waiting | :warning) ::
{:ok, User.t()} | {:error, Ecto.Changeset.t()}
Last Post!
al2o3cr
That message implies that some_functions spec has been parsed as if it was written:
@spec some_function(integer(), :atom) :: {:ok, User.t()} | {:error, Ecto.Changeset.t()}
@spec some_function(integer(), binary(), :unavailable) :: {:ok, User.t()} | {:error, Ecto.Changeset.t()}
which explains why Dialyzer is complaining - some_function(3, :waiting) doesn’t match either of those.
A followup question - why does the compiler think the spec is like that? - is harder to answer.
A good first step would be removing the _build directory in the project to regenerate all the compiled BEAM files; this may not fix the problem but it definitely won’t make things any worse.
If you’re using a language server, check its documentation to see if it has any other artifact hoards that might need clearing.
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