Improve and correct types and specifications in Kernel and STDLIB

Running Dialyzer on the test suites revealed a few type errors.

17 files changed, 59 insertions, 53 deletions

diff --git a/lib/stdlib/doc/src/dets.xml b/lib/stdlib/doc/src/dets.xml
index 2512c84e18..54fefbe2b8 100644
--- a/lib/stdlib/doc/src/dets.xml
+++ b/lib/stdlib/doc/src/dets.xml
@@ -1105,7 +1105,7 @@ fun(X) -> {continue, X} end.            </pre>
             <p>Terminate the traversal and return <c>[<anno>Value</anno> | Acc]</c>.</p>
           </item>
         </taglist>
-        <p>Any other value returned by <c><anno>Fun</anno></c> terminates the
+        <p>Any other value <c><anno>OtherValue</anno></c> returned by <c><anno>Fun</anno></c> terminates the
           traversal and is immediately returned.
           </p>
       </desc>
diff --git a/lib/stdlib/src/dets.erl b/lib/stdlib/src/dets.erl
index 671b5a9dd4..fa0641ffd9 100644
--- a/lib/stdlib/src/dets.erl
+++ b/lib/stdlib/src/dets.erl
@@ -411,7 +411,8 @@ init_table(Tab, InitFun) ->
       InitFun :: fun((Arg) -> Res),
       Arg :: read | close,
       Res :: end_of_input | {[object()], InitFun} | {Data, InitFun} | term(),
-      Options :: [{min_no_slots,no_slots()} | {format,term | bchunk}],
+      Options :: Option | [Option],
+      Option :: {min_no_slots,no_slots()} | {format,term | bchunk},
       Reason :: term(),
       Data :: binary() | tuple().
 
@@ -871,11 +872,15 @@ to_ets(DTab, ETab) ->
 -spec traverse(Name, Fun) -> Return | {'error', Reason} when
       Name :: tab_name(),
       Fun :: fun((Object) -> FunReturn),
-      FunReturn :: 'continue' | {'continue', Val} | {'done', Value},
+      Object :: object(),
+      FunReturn :: 'continue'
+                 | {'continue', Val}
+                 | {'done', Value}
+                 | OtherValue,
+      Return :: [term()] | OtherValue,
       Val :: term(),
       Value :: term(),
-      Object :: object(),
-      Return :: [term()],
+      OtherValue :: term(),
       Reason :: term().
 
 traverse(Tab, Fun) ->
diff --git a/lib/stdlib/src/escript.erl b/lib/stdlib/src/escript.erl
index d67617260e..cd1bacd2f5 100644
--- a/lib/stdlib/src/escript.erl
+++ b/lib/stdlib/src/escript.erl
@@ -62,10 +62,10 @@
 -type zip_create_option() :: term().
 -type section() ::
 	  shebang
-	| {shebang, shebang()}
+	| {shebang, shebang() | default | undefined}
 	| comment
-	| {comment, comment()}
-	| {emu_args, emu_args()}
+	| {comment, comment() | default | undefined}
+	| {emu_args, emu_args() | undefined}
 	| {source, file:filename() | binary()}
 	| {beam, file:filename() | binary()}
 	| {archive, file:filename() | binary()}
diff --git a/lib/stdlib/src/io_lib.erl b/lib/stdlib/src/io_lib.erl
index 165e03e506..0252cdf742 100644
--- a/lib/stdlib/src/io_lib.erl
+++ b/lib/stdlib/src/io_lib.erl
@@ -109,9 +109,9 @@ fwrite(Format, Args) ->
 fread(Chars, Format) ->
     io_lib_fread:fread(Chars, Format).
 
--spec fread(Continuation, String, Format) -> Return when
+-spec fread(Continuation, CharSpec, Format) -> Return when
       Continuation :: continuation() | [],
-      String :: string(),
+      CharSpec :: string() | eof,
       Format :: string(),
       Return :: {'more', Continuation1 :: continuation()}
               | {'done', Result, LeftOverChars :: string()},
diff --git a/lib/stdlib/src/sofs.erl b/lib/stdlib/src/sofs.erl
index d38b8ab37a..34eb224647 100644
--- a/lib/stdlib/src/sofs.erl
+++ b/lib/stdlib/src/sofs.erl
@@ -81,7 +81,8 @@
 -define(ORDTAG, 'OrdSet').
 
 -record(?TAG, {data = [] :: list(), type = type :: term()}).
--record(?ORDTAG, {orddata = {} :: tuple(), ordtype = type :: term()}).
+-record(?ORDTAG, {orddata = {} :: tuple() | atom(),
+                  ordtype = type :: term()}).
 
 -define(LIST(S), (S)#?TAG.data).
 -define(TYPE(S), (S)#?TAG.type).
@@ -375,7 +376,7 @@ to_sets(S) when ?IS_ORDSET(S) ->
 
 -spec(no_elements(ASet) -> NoElements when
       ASet :: a_set() | ordset(),
-      NoElements :: pos_integer()).
+      NoElements :: non_neg_integer()).
 no_elements(S) when ?IS_SET(S) ->
     length(?LIST(S));
 no_elements(S) when ?IS_ORDSET(S), is_tuple(?ORDTYPE(S)) ->
diff --git a/lib/stdlib/src/sys.erl b/lib/stdlib/src/sys.erl
index 8ab72c9b50..f34201604c 100644
--- a/lib/stdlib/src/sys.erl
+++ b/lib/stdlib/src/sys.erl
@@ -154,7 +154,7 @@ log_to_file(Name, FileName, Timeout) ->
 -spec statistics(Name, Flag) -> 'ok' | {'ok', Statistics} when
       Name :: name(),
       Flag :: 'true' | 'false' | 'get',
-      Statistics :: [StatisticsTuple],
+      Statistics :: [StatisticsTuple] | no_statistics,
       StatisticsTuple :: {'start_time', DateTime1}
                        | {'current_time', DateTime2}
                        | {'reductions', non_neg_integer()}
@@ -168,7 +168,7 @@ statistics(Name, Flag) ->
 -spec statistics(Name, Flag, Timeout) -> 'ok' | {'ok', Statistics} when
       Name :: name(),
       Flag :: 'true' | 'false' | 'get',
-      Statistics :: [StatisticsTuple],
+      Statistics :: [StatisticsTuple] | no_statistics,
       StatisticsTuple :: {'start_time', DateTime1}
                        | {'current_time', DateTime2}
                        | {'reductions', non_neg_integer()}
diff --git a/lib/stdlib/test/beam_lib_SUITE.erl b/lib/stdlib/test/beam_lib_SUITE.erl
index 4ccc863795..91fff3cee4 100644
--- a/lib/stdlib/test/beam_lib_SUITE.erl
+++ b/lib/stdlib/test/beam_lib_SUITE.erl
@@ -242,8 +242,8 @@ cmp(doc) -> ["Compare contents of BEAM files and directories"];
 cmp(Conf) when is_list(Conf) ->
     ?line PrivDir = ?privdir,
 
-    ?line Dir1 = filename:join(PrivDir, dir1),
-    ?line Dir2 = filename:join(PrivDir, dir2),
+    ?line Dir1 = filename:join(PrivDir, "dir1"),
+    ?line Dir2 = filename:join(PrivDir, "dir2"),
 
     ok = file:make_dir(Dir1),
     ok = file:make_dir(Dir2),
@@ -292,8 +292,8 @@ cmp_literals(doc) -> ["Compare contents of BEAM files having literals"];
 cmp_literals(Conf) when is_list(Conf) ->
     ?line PrivDir = ?privdir,
 
-    ?line Dir1 = filename:join(PrivDir, dir1),
-    ?line Dir2 = filename:join(PrivDir, dir2),
+    ?line Dir1 = filename:join(PrivDir, "dir1"),
+    ?line Dir2 = filename:join(PrivDir, "dir2"),
 
     ok = file:make_dir(Dir1),
     ok = file:make_dir(Dir2),
@@ -381,7 +381,7 @@ otp_6711(Conf) when is_list(Conf) ->
         (catch {a, beam_lib:strip_files([3])}),
 
     ?line PrivDir = ?privdir,
-    ?line Dir = filename:join(PrivDir, dir),
+    ?line Dir = filename:join(PrivDir, "dir"),
     ?line Lib = filename:join(Dir, "lib"),
     ?line App = filename:join(Lib, "app"),
     ?line EBin = filename:join(App, "ebin"),
@@ -417,8 +417,8 @@ building(doc) -> "Testing building of BEAM files.";
 building(Conf) when is_list(Conf) ->
     ?line PrivDir = ?privdir,
 
-    ?line Dir1 = filename:join(PrivDir, b_dir1),
-    ?line Dir2 = filename:join(PrivDir, b_dir2),
+    ?line Dir1 = filename:join(PrivDir, "b_dir1"),
+    ?line Dir2 = filename:join(PrivDir, "b_dir2"),
 
     ok = file:make_dir(Dir1),
     ok = file:make_dir(Dir2),
@@ -688,7 +688,7 @@ chunk_info(File) ->
     Chunks.
     
 make_beam(Dir, Module, F) ->
-    ?line FileBase = filename:join(Dir, Module),
+    ?line FileBase = filename:join(Dir, atom_to_list(Module)),
     ?line Source = FileBase ++ ".erl",
     ?line BeamFile = FileBase ++ ".beam",
     ?line simple_file(Source, Module, F),
diff --git a/lib/stdlib/test/dets_SUITE.erl b/lib/stdlib/test/dets_SUITE.erl
index 698070368f..22a9d4a7ff 100644
--- a/lib/stdlib/test/dets_SUITE.erl
+++ b/lib/stdlib/test/dets_SUITE.erl
@@ -1516,7 +1516,7 @@ repair(Config, V) ->
     if 
         V =:= 8 ->
             %% first estimated number of objects is wrong, repair once more
-            ?line {ok, Fd} = file:open(Fname, read_write),
+            ?line {ok, Fd} = file:open(Fname, [read,write]),
             NoPos = HeadSize - 8,  % no_objects
             ?line file:pwrite(Fd, NoPos, <<0:32>>), % NoItems
             ok = file:close(Fd),
@@ -3247,7 +3247,7 @@ otp_5402(suite) ->
     [];
 otp_5402(Config) when is_list(Config) ->
     Tab = otp_5402,
-    ?line File = filename:join([cannot, write, this, file]),
+    ?line File = filename:join(["cannot", "write", "this", "file"]),
 
     %% close
     ?line{ok, T} = dets:open_file(Tab, [{ram_file,true},
@@ -3887,7 +3887,7 @@ crash(File, Where) ->
     crash(File, Where, 10).
 
 crash(File, Where, What) when is_integer(What) ->
-    ?line {ok, Fd} = file:open(File, read_write),
+    ?line {ok, Fd} = file:open(File, [read,write]),
     ?line file:position(Fd, Where),
     ?line ok = file:write(Fd, [What]),
     ?line ok = file:close(Fd).
@@ -4031,7 +4031,7 @@ writable(Fname) ->
     ?line file:write_file_info(Fname, Info#file_info{mode = Mode}).
 
 truncate(File, Where) ->
-    ?line {ok, Fd} = file:open(File, read_write),
+    ?line {ok, Fd} = file:open(File, [read,write]),
     ?line file:position(Fd, Where),
     ?line ok = file:truncate(Fd),
     ?line ok = file:close(Fd).
diff --git a/lib/stdlib/test/epp_SUITE.erl b/lib/stdlib/test/epp_SUITE.erl
index 9b024a5b49..57f3f4eddb 100644
--- a/lib/stdlib/test/epp_SUITE.erl
+++ b/lib/stdlib/test/epp_SUITE.erl
@@ -1280,7 +1280,7 @@ eval_tests(Config, Fun, Tests) ->
 
 
 check_test(Config, Test) ->
-    Filename = 'epp_test.erl',
+    Filename = "epp_test.erl",
     ?line PrivDir = ?config(priv_dir, Config),
     ?line File = filename:join(PrivDir, Filename),
     ?line ok = file:write_file(File, Test),
@@ -1293,7 +1293,7 @@ check_test(Config, Test) ->
 
 compile_test(Config, Test0) ->
     Test = [<<"-module(epp_test). -compile(export_all). ">>, Test0],
-    Filename = 'epp_test.erl',
+    Filename = "epp_test.erl",
     ?line PrivDir = ?config(priv_dir, Config),
     ?line File = filename:join(PrivDir, Filename),
     ?line ok = file:write_file(File, Test),
diff --git a/lib/stdlib/test/erl_eval_SUITE.erl b/lib/stdlib/test/erl_eval_SUITE.erl
index 0bcf3c5b71..784c7cb86e 100644
--- a/lib/stdlib/test/erl_eval_SUITE.erl
+++ b/lib/stdlib/test/erl_eval_SUITE.erl
@@ -1189,7 +1189,7 @@ lfh() ->
     {eval, fun(F, As, Bs) -> local_func(F, As, Bs) end}.
 
 local_func(F, As0, Bs0) when is_atom(F) ->
-    {As,Bs} = erl_eval:expr_list(As0, Bs0, {eval,lfh()}),
+    {As,Bs} = erl_eval:expr_list(As0, Bs0, lfh()),
     case erlang:function_exported(?MODULE, F, length(As)) of
 	true ->
 	    {value,apply(?MODULE, F, As),Bs};
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index f980d52e4e..9041adbe5c 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -2981,7 +2981,7 @@ run_test(Conf, Test0, Warnings0) ->
     run_test2(Conf, Test, Warnings0).
 
 run_test2(Conf, Test, Warnings0) ->
-    Filename = 'lint_test.erl',
+    Filename = "lint_test.erl",
     DataDir = ?privdir,
     File = filename:join(DataDir, Filename),
     Opts = case Warnings0 of
diff --git a/lib/stdlib/test/file_sorter_SUITE.erl b/lib/stdlib/test/file_sorter_SUITE.erl
index 80d4ea5fdc..74c08912be 100644
--- a/lib/stdlib/test/file_sorter_SUITE.erl
+++ b/lib/stdlib/test/file_sorter_SUITE.erl
@@ -89,7 +89,7 @@ basic(suite) ->
 basic(Config) when is_list(Config) ->
     Fmt = binary,
     Arg = {format,Fmt},
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
     P0 = pps(),
 
     ?line F1s = [F1] = to_files([[]], Fmt, Config),
@@ -455,7 +455,7 @@ inout(suite) ->
     [];
 inout(Config) when is_list(Config) ->
     BTF = {format, binary_term},
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
 
     %% Input is fun.
     End = fun(read) -> end_of_input end,
@@ -522,7 +522,7 @@ many(doc) ->
 many(suite) ->
     [];
 many(Config) when is_list(Config) ->
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
     PrivDir = ?privdir(Config),
     P0 = pps(),
 
@@ -587,7 +587,7 @@ misc(suite) ->
     [];
 misc(Config) when is_list(Config) ->
     BTF = {format, binary_term},
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
     FFoo = filename:absname(Foo),
     P0 = pps(),
 
@@ -704,7 +704,7 @@ misc(Config) when is_list(Config) ->
 sort(Fmt, XArgs, Config) ->
     Args = make_args(Fmt, [{size,5} | XArgs]),
     TmpArgs = [{tmpdir,?privdir(Config)} | Args],
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
 
     %% Input is a fun. Output is a fun.
     ?line [] = file_sorter:sort(input([], 2, Fmt), output([], Fmt), Args),
@@ -777,7 +777,7 @@ sort(Fmt, XArgs, Config) ->
 keysort(Fmt, XArgs, Config) ->
     Args = make_args(Fmt, [{size,50}, {no_files, 2} | XArgs]),
     TmpArgs = Args ++ [{tmpdir,?privdir(Config)}],
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
 
     %% Input is files. Output is a file.
     ?line ok = file_sorter:keysort(2, [], Foo, Args),
@@ -836,7 +836,7 @@ keysort(Fmt, XArgs, Config) ->
 
 merge(Fmt, XArgs, Config) ->
     Args = make_args(Fmt, [{size,5} | XArgs]),
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
 
     %% Input is a file. Output is a fun.
     ?line [] = file_sorter:merge([], output([], Fmt), Args),
@@ -873,7 +873,7 @@ merge(Fmt, XArgs, Config) ->
 
 keymerge(Fmt, XArgs, Config) ->
     Args = make_args(Fmt, [{size,50}, {no_files, 2} | XArgs]),
-    Foo = outfile(foo, Config),
+    Foo = outfile("foo", Config),
 
     %% Input is files. Output is a file.
     ?line ok = file_sorter:keymerge(2, [], Foo, Args),
diff --git a/lib/stdlib/test/filelib_SUITE.erl b/lib/stdlib/test/filelib_SUITE.erl
index a355097fe2..3010f5e760 100644
--- a/lib/stdlib/test/filelib_SUITE.erl
+++ b/lib/stdlib/test/filelib_SUITE.erl
@@ -243,7 +243,7 @@ otp_5960(doc) ->
     ["Test that filelib:ensure_dir/1 returns ok or {error,Reason}"];
 otp_5960(Config) when is_list(Config) ->
     ?line PrivDir = ?config(priv_dir, Config),
-    ?line Dir = filename:join(PrivDir, otp_5960_dir),
+    ?line Dir = filename:join(PrivDir, "otp_5960_dir"),
     ?line Name1 = filename:join(Dir, name1),
     ?line Name2 = filename:join(Dir, name2),
     ?line ok = filelib:ensure_dir(Name1), % parent is created
@@ -268,7 +268,7 @@ otp_5960(Config) when is_list(Config) ->
 
 ensure_dir_eexist(Config) when is_list(Config) ->
     ?line PrivDir = ?config(priv_dir, Config),
-    ?line Dir = filename:join(PrivDir, ensure_dir_eexist),
+    ?line Dir = filename:join(PrivDir, "ensure_dir_eexist"),
     ?line Name = filename:join(Dir, "same_name_as_file_and_dir"),
     ?line ok = filelib:ensure_dir(Name),
     ?line ok = file:write_file(Name, <<"some string\n">>),
diff --git a/lib/stdlib/test/string_SUITE.erl b/lib/stdlib/test/string_SUITE.erl
index 1dcd4be21e..6969c095a0 100644
--- a/lib/stdlib/test/string_SUITE.erl
+++ b/lib/stdlib/test/string_SUITE.erl
@@ -273,9 +273,9 @@ words(Config) when is_list(Config) ->
     ?line 2 = string:words("2.35", $.),
     ?line 100 = string:words(string:copies(". ", 100)),
     %% invalid arg type
-    ?line {'EXIT',_} = (catch string:chars(hej)),
+    ?line {'EXIT',_} = (catch string:chars(hej, 1)),
     %% invalid arg type
-    ?line {'EXIT',_} = (catch string:chars("hej", " ")),
+    ?line {'EXIT',_} = (catch string:chars("hej", 1, " ")),
     ok.
 
 
diff --git a/lib/stdlib/test/supervisor_bridge_SUITE.erl b/lib/stdlib/test/supervisor_bridge_SUITE.erl
index f2dbad0b3b..c4d696564d 100644
--- a/lib/stdlib/test/supervisor_bridge_SUITE.erl
+++ b/lib/stdlib/test/supervisor_bridge_SUITE.erl
@@ -158,7 +158,7 @@ internal_loop(State) ->
 terminate(Reason,{Parent,Worker}) ->
     %% This func knows about supervisor_bridge
     io:format("Terminating bridge...\n"),
-    exit(kill,Worker),
+    exit(Worker,kill),
     Parent ! {dying,Reason},
     anything.
 
diff --git a/lib/stdlib/test/sys_SUITE.erl b/lib/stdlib/test/sys_SUITE.erl
index 72b089aa3f..fe039e8bcc 100644
--- a/lib/stdlib/test/sys_SUITE.erl
+++ b/lib/stdlib/test/sys_SUITE.erl
@@ -71,7 +71,7 @@ log_to_file(Config) when is_list(Config) ->
     ?line ok = sys:log_to_file(?server,TempName),
     ?line {ok,-44} = public_call(44),
     ?line ok = sys:log_to_file(?server,false),
-    ?line {ok,Fd} = file:open(TempName,read),
+    ?line {ok,Fd} = file:open(TempName,[read]),
     ?line Msg1 = io:get_line(Fd,''),
     ?line Msg2 = io:get_line(Fd,''),
     ?line file:close(Fd),
diff --git a/lib/stdlib/test/tar_SUITE.erl b/lib/stdlib/test/tar_SUITE.erl
index e32704ca65..48f58cd05d 100644
--- a/lib/stdlib/test/tar_SUITE.erl
+++ b/lib/stdlib/test/tar_SUITE.erl
@@ -65,7 +65,7 @@ borderline(Config) when is_list(Config) ->
 
     ?line {ok, Cwd} = file:get_cwd(),
     ?line RootDir = ?config(priv_dir, Config),
-    ?line TempDir = remove_prefix(Cwd++"/", filename:join(RootDir, borderline)),
+    ?line TempDir = remove_prefix(Cwd++"/", filename:join(RootDir, "borderline")),
     ?line ok = file:make_dir(TempDir),
 
     ?line Record = 512,
@@ -323,12 +323,12 @@ create_long_names(doc) ->
 create_long_names(Config) when is_list(Config) ->
     ?line PrivDir = ?config(priv_dir, Config),
     ?line ok = file:set_cwd(PrivDir),
-    Dirs = [aslfjkshjkhliuf,
-	    asdhjfehnbfsky,
-	    sahajfskdfhsz,
-	    asldfkdlfy4y8rchg,
-	    f7nafhjgffagkhsfkhsjk,
-	    dfjasldkfjsdkfjashbv],
+    Dirs = ["aslfjkshjkhliuf",
+	    "asdhjfehnbfsky",
+	    "sahajfskdfhsz",
+	    "asldfkdlfy4y8rchg",
+	    "f7nafhjgffagkhsfkhsjk",
+	    "dfjasldkfjsdkfjashbv"],
 
     ?line DeepDir = make_dirs(Dirs, []),
     ?line AFile = filename:join(DeepDir, "a_file"),
@@ -487,7 +487,7 @@ extract_from_binary_compressed(Config) when is_list(Config) ->
     
     %% Trying extracting from a binary.
     ?line ok = erl_tar:extract({binary,Bin}, [compressed,{cwd,ExtractDir}]),
-    ?line {ok,List} = file:list_dir(filename:join(ExtractDir, ddll_SUITE_data)),
+    ?line {ok,List} = file:list_dir(filename:join(ExtractDir, "ddll_SUITE_data")),
     ?line io:format("~p\n", [List]),
     ?line 19 = length(List),
 
@@ -676,7 +676,7 @@ cooked_compressed(Config) when is_list(Config) ->
 		  end, List),
 
     %% Clean up.
-    ?line delete_files([filename:join(PrivDir, ddll_SUITE_data)]),
+    ?line delete_files([filename:join(PrivDir, "ddll_SUITE_data")]),
     ok.
 
 memory(doc) ->