BER: Suppress dialyzer warnings for encode_bit_string/4

We don't want to touch the code used for encoding BIT STRINGs when
'legacy_erl_types' is active, since it will be removed within two
or three major releases. But we do want to suppress the dialyzer
warnings in the meantime. The easiest way is to call
encode_bit_string/4 with unknown types from an exported function
that is never actually called like this:

-export(['dialyzer-suppressions'/0]).

'dialyzer-suppressions'(Arg) ->
    {A,B,C,D} = Arg,
    encode_bit_string(A, B, C, D),
    ok.

4 files changed, 35 insertions, 2 deletions

diff --git a/lib/asn1/src/asn1ct_func.erl b/lib/asn1/src/asn1ct_func.erl
index 33f998722a..fb94f65b32 100644
--- a/lib/asn1/src/asn1ct_func.erl
+++ b/lib/asn1/src/asn1ct_func.erl
@@ -19,7 +19,8 @@
 %%
 
 -module(asn1ct_func).
--export([start_link/0,need/1,call/3,call_gen/3,call_gen/4,generate/1]).
+-export([start_link/0,need/1,call/3,call_gen/3,call_gen/4,
+	 generate/1,is_used/1]).
 -export([init/1,handle_call/3,handle_cast/2,terminate/2]).
 
 start_link() ->
@@ -63,6 +64,10 @@ generate(Fd) ->
     Funcs = sofs:to_external(Funcs0),
     ok = file:write(Fd, Funcs).
 
+is_used({_,_,_}=MFA) ->
+    req({is_used,MFA}).
+
+
 req(Req) ->
     gen_server:call(get(?MODULE), Req, infinity).
 
@@ -103,7 +108,10 @@ handle_call({gen_func,Prefix,Key,GenFun}, _From, #st{gen=G0,gc=Gc0}=St) ->
 	    {reply,Name,St#st{gen=G,gc=Gc}};
 	{value,{Name,_}} ->
 	    {reply,Name,St}
-    end.
+    end;
+handle_call({is_used,MFA}, _From, #st{used=Used}=St) ->
+    {reply,gb_sets:is_member(MFA, Used),St}.
+
 
 terminate(_, _) ->
     ok.
diff --git a/lib/asn1/src/asn1ct_gen.erl b/lib/asn1/src/asn1ct_gen.erl
index bfe7df9713..af1301eb42 100644
--- a/lib/asn1/src/asn1ct_gen.erl
+++ b/lib/asn1/src/asn1ct_gen.erl
@@ -43,6 +43,8 @@
 -export([gen_encode_constructed/4,
 	 gen_decode_constructed/4]).
 
+-define(SUPPRESSION_FUNC, 'dialyzer-suppressions').
+
 %% pgen(Outfile, Erules, Module, TypeOrVal, Options)
 %% Generate Erlang module (.erl) and (.hrl) file corresponding to an ASN.1 module
 %% .hrl file is only generated if necessary
@@ -85,12 +87,18 @@ pgen_module(OutFile,Erules,Module,
 	  "%%%",nl,
 	  "%%% Run-time functions.",nl,
 	  "%%%",nl]),
+    dialyzer_suppressions(Erules),
     Fd = get(gen_file_out),
     asn1ct_func:generate(Fd),
     close_output_file(),
     _ = erase(outfile),
     asn1ct:verbose("--~p--~n",[{generated,ErlFile}],Options).
 
+dialyzer_suppressions(Erules) ->
+    emit([nl,
+	  {asis,?SUPPRESSION_FUNC},"(Arg) ->",nl]),
+    Rtmod = ct_gen_module(Erules),
+    Rtmod:dialyzer_suppressions(Erules).
 
 pgen_typeorval(Erules,Module,N2nConvEnums,{Types,Values,_Ptypes,_Classes,Objects,ObjectSets}) ->
     Rtmod = ct_gen_module(Erules),
@@ -791,6 +799,7 @@ gen_decode_constructed(Erules,Typename,InnerType,D) when is_record(D,typedef) ->
 pgen_exports(Erules,_Module,{Types,Values,_,_,Objects,ObjectSets}) ->
     emit(["-export([encoding_rule/0,bit_string_format/0,",nl,
 	  "         legacy_erlang_types/0]).",nl]),
+    emit(["-export([",{asis,?SUPPRESSION_FUNC},"/1]).",nl]),
     case Types of
 	[] -> ok;
 	_ ->
diff --git a/lib/asn1/src/asn1ct_gen_ber_bin_v2.erl b/lib/asn1/src/asn1ct_gen_ber_bin_v2.erl
index 6db31c5ea2..4c08f24619 100644
--- a/lib/asn1/src/asn1ct_gen_ber_bin_v2.erl
+++ b/lib/asn1/src/asn1ct_gen_ber_bin_v2.erl
@@ -32,6 +32,7 @@
 -export([encode_tag_val/3]).
 -export([gen_inc_decode/2,gen_decode_selected/3]).
 -export([extaddgroup2sequence/1]).
+-export([dialyzer_suppressions/1]).
 
 -import(asn1ct_gen, [emit/1,demit/1]).
 
@@ -65,6 +66,17 @@
 %%===============================================================================
 %%===============================================================================
 
+dialyzer_suppressions(_) ->
+    case asn1ct:use_legacy_types() andalso
+	asn1ct_func:is_used({ber,encode_bit_string,4}) of
+	false ->
+	    ok;
+	true ->
+	    emit(["    {A,B,C,D} = Arg,",nl,
+		  "    encode_bit_string(A, B, C, D),",nl])
+    end,
+    emit(["    ok.",nl]).
+
 %%===============================================================================
 %% encode #{typedef, {pos, name, typespec}}
 %%===============================================================================
diff --git a/lib/asn1/src/asn1ct_gen_per.erl b/lib/asn1/src/asn1ct_gen_per.erl
index 519ce9f054..cf6ec49e9f 100644
--- a/lib/asn1/src/asn1ct_gen_per.erl
+++ b/lib/asn1/src/asn1ct_gen_per.erl
@@ -32,6 +32,7 @@
 -export([gen_encode/2, gen_encode/3]).
 -export([gen_dec_external/2]).
 -export([extaddgroup2sequence/1]).
+-export([dialyzer_suppressions/1]).
 
 -import(asn1ct_gen, [emit/1,demit/1]).
 -import(asn1ct_func, [call/3]).
@@ -40,6 +41,9 @@
 %% Generate ENCODING ******************************
 %%****************************************x
 
+dialyzer_suppressions(_) ->
+    emit(["    ok.",nl]).
+
 
 gen_encode(Erules,Type) when is_record(Type,typedef) ->
     gen_encode_user(Erules,Type).