Fix "overlapping domain" Dialyzer warning for '#is_record-'/{1,2}

These contracts will usually not be seen by the user, and are ignored
by Dialyzer because they have overlapping domains, so there is not
much point in using them.  Replace with simpler contracts for now.

src/exprecs.erl

@@ -136,9 +136,8 @@
 %% '#pos-'(s, Attr) ->
 %%     '#pos-s'(Attr).
 %%
-%% -spec '#is_record-'(#r{}) -> true;
-%%                    (#s{}) -> true;
-%%                    (any()) -> false.
+%% -spec '#is_record-'(any()) -> boolean().
+%%                    
 %% '#is_record-'(X) ->
 %%     if
 %%         is_record(X, r) ->
@@ -149,9 +148,8 @@
 %%             false
 %%     end.
 %%
-%% -spec '#is_record-'(r, #r{}) -> true;
-%%                    (s, #s{}) -> true;
-%%                    (any(), any()) -> false.
+%% -spec '#is_record-'(any(), any()) -> boolean().
+%%                    
 %% '#is_record-'(s, Rec) when tuple_size(Rec) == 2, element(1, Rec) == s ->
 %%     true;
 %% '#is_record-'(r, Rec) when tuple_size(Rec) == 4, element(1, Rec) == r ->
@@ -756,6 +754,7 @@ t_atom(L, A)     -> {atom, L, A}.
 t_integer(L)     -> {type, L, integer, []}.
 t_integer(L, I)  -> {integer, L, I}.
 t_list(L, Es)    -> {type, L, list, Es}.
+t_boolean(L)     -> {type, L, boolean, []}.
 %% t_tuple(L, Es) -> {type, L, tuple, Es}.
 t_record(L, A)   -> {type, L, record, [{atom, L, A}]}.
 
@@ -929,10 +928,14 @@ f_info(Acc, L) ->
 f_isrec_2(#pass1{records = Rs, exports = Es} = Acc, L) ->
     Fname = list_to_atom(fname_prefix(is_record, Acc)),
     Info = [{R,length(As) + 1} || {R,As} <- Rs, lists:member(R, Es)],
-    [funspec(L, Fname,
-	     [{[t_atom(L, R), t_record(L, R)], t_atom(L, true)}
-	      || R <- Es] ++
-		 [{[t_any(L), t_any(L)], t_atom(L, false)}]),
+    [%% This contract is correct, but is ignored by Dialyzer because it
+     %% has overlapping domains:
+     %% funspec(L, Fname,
+     %% 	     [{[t_atom(L, R), t_record(L, R)], t_atom(L, true)}
+     %% 	      || R <- Es] ++
+     %% 		 [{[t_any(L), t_any(L)], t_atom(L, false)}]),
+     %% This is less specific, but more useful to Dialyzer:
+     funspec(L, Fname, [{[t_any(L), t_any(L)], t_boolean(L)}]),
      {function, L, Fname, 2,
       lists:map(
 	fun({R, Ln}) ->
@@ -1007,10 +1010,14 @@ f_pos_2(#pass1{exports = Es} = Acc, L) ->
 
 f_isrec_1(Acc, L) ->
     Fname = list_to_atom(fname_prefix(is_record, Acc)),
-    [funspec(L, Fname,
-	     [{[t_record(L, R)], t_atom(L, true)}
-	      || R <- Acc#pass1.exports]
-	     ++ [{[t_any(L)], t_atom(L, false)}]),
+    [%% This contract is correct, but is ignored by Dialyzer because it
+     %% has overlapping domains:
+     %% funspec(L, Fname,
+     %% 	     [{[t_record(L, R)], t_atom(L, true)}
+     %% 	      || R <- Acc#pass1.exports]
+     %% 	     ++ [{[t_any(L)], t_atom(L, false)}]),
+     %% This is less specific, but more useful to Dialyzer:
+     funspec(L, Fname, [{[t_any(L)], t_boolean(L)}]),
      {function, L, Fname, 1,
       [{clause, L,
 	[{var, L, 'X'}],