alias two -opaque types with plain -type to address dialyzer issue

In riak_kv_gcounter.erl, redeclare gcounter() with -type (as
gcounter_()) for local use, to make dialyzer accept the specs for
merge/2,3.  Apparently, dialyzer only accepts standalone variables for
args having an opaque type spec, whereas we call those functions with
an expressly constructed lists.

Same with pncounter() in riak_kv_pncounter.erl.

Author: hmmr

dialyzer.ignore-warnings

@@ -1,11 +1,6 @@
 riak_core_pb.erl
-riak_kv_gcounter.erl:86: Function merge/2 has no local return
-riak_kv_gcounter.erl:87: The call riak_kv_gcounter:merge(GCnt1::any(),GCnt2::any(),[]) does not have an opaque term of type riak_kv_gcounter:gcounter() as 3rd argument
-riak_kv_gcounter.erl:100: The call riak_kv_gcounter:merge(Rest::any(),RestOfClock2::[tuple()],[{_,_},...]) does not have opaque terms as 2nd and 3rd arguments
-riak_kv_gcounter.erl:102: The call riak_kv_gcounter:merge(Rest::any(),Clock2::[tuple()],[{_,_},...]) does not have opaque terms as 2nd and 3rd arguments
 riak_kv_pipe_index.erl:164: Function queue_existing_pipe/4 has no local return
 riak_kv_pipe_listkeys.erl:159: Function queue_existing_pipe/3 has no local return
-riak_kv_pncounter.erl:101: Function merge/2 has no local return
 riak_kv_put_fsm.erl:822: The pattern <[COP = {'counter_op', _Amt} | T], Acc> can never match the type <[{'details' | 'dw' | 'n_val' | 'pw' | 'retry_put_coordinator_failure' | 'returnbody' | 'sloppy_quorum' | 'timeout' | 'update_last_modified' | 'w','false' | 'infinity' | 'true' | [any()] | non_neg_integer()},...],[{'details' | 'dw' | 'n_val' | 'pw' | 'retry_put_coordinator_failure' | 'returnbody' | 'sloppy_quorum' | 'timeout' | 'update_last_modified' | 'w','false' | 'infinity' | 'true' | [any()] | non_neg_integer()}]>
 riak_kv_put_fsm.erl:825: The pattern <[COP = {'crdt_op', _Op} | T], Acc> can never match the type <[{'details' | 'dw' | 'n_val' | 'pw' | 'retry_put_coordinator_failure' | 'returnbody' | 'sloppy_quorum' | 'timeout' | 'update_last_modified' | 'w','false' | 'infinity' | 'true' | [any()] | non_neg_integer()},...],[{'details' | 'dw' | 'n_val' | 'pw' | 'retry_put_coordinator_failure' | 'returnbody' | 'sloppy_quorum' | 'timeout' | 'update_last_modified' | 'w','false' | 'infinity' | 'true' | [any()] | non_neg_integer()}]>
 riak_kv_util.erl:304: The pattern 'error' can never match the type 'ok' | 'undefined'

src/riak_kv_gcounter.erl

@@ -52,6 +52,11 @@
 -export_type([gcounter/0, gcounter_op/0]).
 
 -opaque gcounter() :: [entry()].
+%% Redeclaring gcounter() with -type for local use, to make dialyzer
+%% accept specs for merge/2,3.  Apparently, dialyzer only accepts
+%% standalone variables for args having an opaque type spec, whereas
+%% we call those functions with an expressly constructed lists.
+-type gcounter_() :: [entry()].
 
 -type entry() :: {Actor::term(), Count::pos_integer()}.
 -type gcounter_op() :: increment | {increment, pos_integer()}.
@@ -82,12 +87,12 @@ update({increment, Amount}, Actor, GCnt) when is_integer(Amount), Amount > 0 ->
 
 %% @doc Merge two `gcounter()'s to a single `gcounter()'. This is the Least Upper Bound
 %% function described in the literature.
--spec merge(gcounter(), gcounter()) -> gcounter().
+-spec merge(gcounter_(), gcounter_()) -> gcounter_().
 merge(GCnt1, GCnt2) ->
     merge(GCnt1, GCnt2, []).
 
 %% @private merge two counters.
--spec merge(gcounter(), gcounter(), gcounter()) -> gcounter().
+-spec merge(gcounter_(), gcounter_(), gcounter_()) -> gcounter_().
 merge([], [], Acc) ->
     lists:reverse(Acc);
 merge(LeftOver, [], Acc) ->

src/riak_kv_pncounter.erl

@@ -50,6 +50,15 @@
 -export_type([pncounter/0, pncounter_op/0]).
 
 -opaque pncounter() :: {riak_kv_gcounter:gcounter(), riak_kv_gcounter:gcounter()}.
+%% Redeclaring pncounter() with -type to please dialyzer, which would
+%% otherwise issue the following warning:
+%%  riak_kv_pncounter.erl:100: Invalid type specification for
+%%    function riak_kv_pncounter:merge/2. The success typing is
+%%    ({[{_,pos_integer()}],[{_,pos_integer()}]},{[{_,pos_integer()}],[{_,pos_integer()}]})
+%%    -> {[{_,pos_integer()}],[{_,pos_integer()}]}
+%% Apparently, dialyzer only accepts plain variables for args having
+%% an opaque type spec.
+-type  pncounter_() :: {riak_kv_gcounter:gcounter(), riak_kv_gcounter:gcounter()}.
 -type pncounter_op() :: riak_kv_gcounter:gcounter_op() | decrement_op().
 -type decrement_op() :: decrement | {decrement, pos_integer()}.
 
@@ -97,7 +106,7 @@ update({decrement, By}, Actor, {Incr, Decr}) when is_integer(By), By > 0 ->
 
 %% @doc Merge two `pncounter()'s to a single `pncounter()'. This is the Least Upper Bound
 %% function described in the literature.
--spec merge(pncounter(), pncounter()) -> pncounter().
+-spec merge(pncounter_(), pncounter_()) -> pncounter_().
 merge({Incr1, Decr1}, {Incr2, Decr2}) ->
     MergedIncr =  riak_kv_gcounter:merge(Incr1, Incr2),
     MergedDecr =  riak_kv_gcounter:merge(Decr1, Decr2),