dialyzer: Introduce nominal types

This PR implements [EEP-69: Nominal Types](https://www.erlang.org/eeps/eep-0069)
in Dialyzer. As a side effect, nominal types can encode opaque types. We
changed all opaque-handling logic and improved opaque warnings in
Dialyzer.

All existing Erlang type systems are structural: two types are seen as
equivalent if their structures are the same. Type comparison are based
on the structures of the types, not on how the user explicitly defines
them. For example, in the following example, `meter()` and `foot()` are
equivalent. The two types can be used interchangeably. Neither of them
differ from the basic type `integer()`.

    -type meter() :: integer().
    -type foot() :: integer().

Nominal typing is an alternative type system, where two types are
equivalent if and only if they are declared with the same type name.
The EEP proposes one new syntax `-nominal` for declaring nominal types.
Under nominal typing, `meter()` and `foot()` are no longer compatible.
Whenever a function expects type `meter()`, passing in type `foot()`
would result in a Dialyzer error.

    -nominal meter() :: integer().
    -nominal foot() :: integer().

More nominal type-checking rules can be found in the EEP. It is worth
noting that most work for adding nominal types and type-checking
is in `erl_types.erl`. The rest are changes that removed the previous
opaque type-checking, and added an improved version of it using nominal
type-checking with reworked warnings.

Backwards compatibility for opaque type-checking is **not** preserved
by this PR. Previous opaque warnings can appear with slightly different
wordings. A new kind of opaque warning `opaque_union` is added, together
with a Dialyzer option `no_opaque_union` to turn this kind of warnings
off.

This PR is likely not bug-free, but not having it in master is blocking
other changes to Dialyzer. Once nominal type-checking and the new opaque
type-checking are applied to more codebases, we will fix the bugs as
they appear.

Co-authored-by: John Högberg <[email protected]>

bootstrap/lib/compiler/ebin/compiler.app

@@ -1,7 +1,7 @@
 % This is an -*- erlang -*- file.
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2023. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2024. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@
 
 {application, compiler,
  [{description, "ERTS  CXC 138 10"},
-  {vsn, "8.3.2"},
+  {vsn, "8.5.2"},
   {modules, [
 	     beam_a,
 	     beam_asm,
@@ -31,6 +31,7 @@
 	     beam_dict,
 	     beam_digraph,
 	     beam_disasm,
+         beam_doc,
 	     beam_flatten,
 	     beam_jump,
 	     beam_listing,
@@ -43,11 +44,11 @@
              beam_ssa_check,
              beam_ssa_codegen,
              beam_ssa_dead,
+             beam_ssa_destructive_update,
              beam_ssa_lint,
              beam_ssa_opt,
              beam_ssa_pp,
              beam_ssa_pre_codegen,
-             beam_ssa_private_append,
              beam_ssa_recv,
              beam_ssa_share,
              beam_ssa_ss,
@@ -76,12 +77,13 @@
 	     sys_core_fold_lists,
 	     sys_core_inline,
 	     sys_core_prepare,
+             sys_coverage,
 	     sys_messages,
 	     sys_pre_attributes,
 	     v3_core
 	    ]},
   {registered, []},
   {applications, [kernel, stdlib]},
   {env, []},
-  {runtime_dependencies, ["stdlib-5.0","kernel-8.4","erts-13.0",
+  {runtime_dependencies, ["stdlib-6.0","kernel-8.4","erts-13.0",
 			  "crypto-5.1"]}]}.

bootstrap/lib/kernel/ebin/kernel.app

@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1996-2023. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2024. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -22,7 +22,7 @@
 {application, kernel,
  [
   {description, "ERTS  CXC 138 10"},
-  {vsn, "9.0.2"},
+  {vsn, "10.1.1"},
   {modules, [application,
 	     application_controller,
 	     application_master,
@@ -72,6 +72,7 @@
              logger_filters,
              logger_formatter,
              logger_h_common,
+             logger_handler,
              logger_handler_watcher,
              logger_olp,
              logger_proxy,
@@ -88,6 +89,7 @@
 	     user_drv,
 	     user_sup,
              prim_tty,
+             prim_tty_sighandler,
              disk_log,
              disk_log_1,
              disk_log_server,
@@ -121,6 +123,7 @@
 	     seq_trace,
              socket,
 	     standard_error,
+             trace,
 	     wrap_log_reader]},
   {registered, [application_controller,
 		erl_reply,
@@ -158,10 +161,11 @@
          {net_tickintensity, 4},
          {net_ticktime, 60},
          {prevent_overlapping_partitions, true},
-         {shell_docs_ansi,auto}
+         {shell_docs_ansi,auto},
+         {shell_history_drop,[]}
         ]},
   {mod, {kernel, []}},
-  {runtime_dependencies, ["erts-14.0", "stdlib-5.0",
+  {runtime_dependencies, ["erts-15.1", "stdlib-6.0",
                           "sasl-3.0", "crypto-5.0"]}
   ]
 }.

bootstrap/lib/stdlib/ebin/stdlib.app

@@ -2,7 +2,7 @@
 %% 
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2023. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2024. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -20,7 +20,7 @@
 %%
 {application, stdlib,
  [{description, "ERTS  CXC 138 10"},
-  {vsn, "5.0.2"},
+  {vsn, "6.1.2"},
   {modules, [argparse,
 	     array,
 	     base64,
@@ -37,6 +37,7 @@
 	     digraph,
 	     digraph_utils,
 	     edlin,
+	     edlin_key,
 	     edlin_context,
 	     edlin_expand,
 	     edlin_type_suggestion,
@@ -77,6 +78,7 @@
 	     io_lib_format,
 	     io_lib_fread,
 	     io_lib_pretty,
+             json,
 	     lists,
 	     log_mf_h,
 	     maps,
@@ -99,6 +101,7 @@
 	     shell,
 	     shell_default,
 	     shell_docs,
+         shell_docs_markdown,
 	     slave,
 	     sofs,
 	     string,
@@ -115,6 +118,6 @@
                dets]},
   {applications, [kernel]},
   {env, []},
-  {runtime_dependencies, ["sasl-3.0","kernel-9.0","erts-13.1","crypto-4.5",
+  {runtime_dependencies, ["sasl-3.0","kernel-10.0","erts-15.0","crypto-4.5",
 			  "compiler-5.0"]}
 ]}.

lib/common_test/src/ct_ssh.erl

@@ -1362,6 +1362,7 @@ init(KeyOrName, {ConnType,Addr,Port}, AllOpts) ->
 			      target=KeyOrName}}
     end.
 
+-dialyzer({no_opaque_union, [handle_msg/2]}).
 -doc false.
 handle_msg(sftp_connect, State) ->
     #state{ssh_ref=SSHRef, target=Target} = State,

lib/compiler/src/beam_core_to_ssa.erl

@@ -1566,7 +1566,7 @@ partition_intersection([U|_]=Us, [_,_|_]=Cs0, St0) ->
     case find_key_intersection(Ps) of
         none ->
             {Us,Cs0,St0};
-        Ks ->
+        {ok, Ks} ->
             Cs1 = map(fun(#iclause{pats=[Arg|Args]}=C) ->
                               {Arg1,Arg2} = partition_keys(Arg, Ks),
                               C#iclause{pats=[Arg1,Arg2|Args]}
@@ -1601,7 +1601,7 @@ find_key_intersection(Ps) ->
                     %% the keys could only make the code worse.
                     none;
                 false ->
-                    Intersection
+                    {ok, Intersection}
             end
     end.
 

lib/compiler/src/beam_disasm.erl

@@ -41,8 +41,8 @@
 %%-----------------------------------------------------------------------
 
 -type index()        :: non_neg_integer().
--type literals()     :: 'none' | gb_trees:tree(index(), term()).
--type types()        :: 'none' | gb_trees:tree(index(), term()).
+-type literals()     :: gb_trees:tree(index(), term()).
+-type types()        :: gb_trees:tree(index(), term()).
 -type symbolic_tag() :: 'a' | 'f' | 'h' | 'i' | 'u' | 'x' | 'y' | 'z'.
 -type disasm_tag()   :: symbolic_tag() | 'fr' | 'atom' | 'float' | 'literal'.
 -type disasm_term()  :: 'nil' | {disasm_tag(), _}.
@@ -254,7 +254,7 @@ disasm_lambdas(<<>>, _, _) -> [].
 -spec beam_disasm_types('none' | binary()) -> types().
 
 beam_disasm_types(none) ->
-    none;
+    gb_trees:empty();
 beam_disasm_types(<<Version:32,Count:32,Table0/binary>>) ->
     case beam_types:convert_ext(Version, Table0) of
         none ->
@@ -265,7 +265,7 @@ beam_disasm_types(<<Version:32,Count:32,Table0/binary>>) ->
             Res
     end;
 beam_disasm_types(<<_/binary>>) ->
-    none.
+    gb_trees:empty().
 
 disasm_types(Types0, Index) ->
     case beam_types:decode_ext(Types0) of

lib/compiler/src/beam_doc.erl

@@ -61,7 +61,7 @@
                deprecated = #{}    :: map(),
 
                docformat = ?DEFAULT_FORMAT :: binary(),
-               moduledoc = {?DEFAULT_MODULE_DOC_LOC, none} :: {integer() | erl_anno:anno(), none | map() | hidden},
+               moduledoc = {erl_anno:new(?DEFAULT_MODULE_DOC_LOC), none} :: {erl_anno:anno(), none | map() | hidden},
                moduledoc_meta = none :: none | #{ _ := _ },
 
                behaviours = []     :: list(module()),
@@ -110,7 +110,7 @@
                %% populates all function / types, callbacks. it is updated on an ongoing basis
                %% since a doc attribute `doc ...` is not known in a first pass to be attached
                %% to a function / type / callback.
-               docs = #{} :: #{{Attribute :: function | type | opaque | callback,
+               docs = #{} :: #{{Attribute :: function | type | opaque | nominal | callback,
                                 FunName :: atom(),
                                 Arity :: non_neg_integer()}
                                =>
@@ -145,7 +145,7 @@
                %% -doc #{author => "X"}.
                %% -doc foo() -> ok.
                %%
-               %% thus, after reading a terminal AST node (spec, type, fun declaration, opaque, callback),
+               %% thus, after reading a terminal AST node (spec, type, fun declaration, opaque, nominal, callback),
                %% the intermediate state saved in the fields below needs to be
                %% saved in the `docs` field.
 
@@ -459,7 +459,7 @@ track_documentation(_, State) ->
 upsert_documentation_from_terminal_item({function, Anno, F, Arity, _}, State) ->
    upsert_documentation(function, F, Arity, Anno, State);
 upsert_documentation_from_terminal_item({attribute, Anno, TypeOrOpaque, {TypeName, _TypeDef, TypeArgs}},State)
-  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque ->
+  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque; TypeOrOpaque =:= nominal ->
    Arity = length(fun_to_varargs(TypeArgs)),
    upsert_documentation(type, TypeName, Arity, Anno, State);
 upsert_documentation_from_terminal_item({attribute, Anno, callback, {{CB, Arity}, _Form}}, State) ->
@@ -470,6 +470,7 @@ upsert_documentation_from_terminal_item(_, State) ->
 upsert_documentation(Tag, Name, Arity, Anno, State) when Tag =:= function;
                                                          Tag =:= type;
                                                          Tag =:= opaque;
+                                                         Tag =:= nominal;
                                                          Tag =:= callback ->
    Docs = State#docs.docs,
    State1 = case maps:get({Tag, Name, Arity}, Docs, none) of
@@ -579,7 +580,7 @@ extract_hidden_types0({attribute, _Anno, doc, _}, State) ->
 extract_hidden_types0({attribute, _Anno, TypeOrOpaque, {Name, _Type, Args}},
                       #docs{hidden_status = hidden,
                             hidden_types = HiddenTypes}=State)
-  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque ->
+  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque; TypeOrOpaque =:= nominal ->
    State#docs{hidden_status = none,
               hidden_types = sets:add_element({Name, length(Args)}, HiddenTypes)};
 extract_hidden_types0(_, State) ->
@@ -593,7 +594,7 @@ extract_hidden_types0(_, State) ->
 %% #{{TypeName, length(Args)} => Anno}.
 %%
 extract_type_defs0({attribute, Anno, TypeOrOpaque, {TypeName, _TypeDef, TypeArgs}}, #docs{type_defs = TypeDefs}=State)
-  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque ->
+  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque; TypeOrOpaque =:= nominal ->
    Args = fun_to_varargs(TypeArgs),
    Type = {TypeName, length(Args)},
    State#docs{type_defs = TypeDefs#{Type => Anno}};
@@ -660,7 +661,7 @@ update_docstatus(State, V) ->
 
 update_ast(function, #docs{ast_fns=AST}=State, Fn) ->
     State#docs{ast_fns = [Fn | AST]};
-update_ast(Type,#docs{ast_types=AST}=State, Fn) when Type =:= type; Type =:= opaque->
+update_ast(Type,#docs{ast_types=AST}=State, Fn) when Type =:= type; Type =:= opaque; Type =:= nominal->
     State#docs{ast_types = [Fn | AST]};
 update_ast(callback, #docs{ast_callbacks = AST}=State, Fn) ->
     State#docs{ast_callbacks = [Fn | AST]}.
@@ -873,7 +874,7 @@ extract_documentation0({function, _Anno, F, A, _Body}=AST, State) ->
     State1 = remove_exported_type_info({function, F, A}, State),
     extract_documentation_from_funs(AST, State1);
 extract_documentation0({attribute, _Anno, TypeOrOpaque, _}=AST,State)
-  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque ->
+  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque; TypeOrOpaque =:= nominal ->
     extract_documentation_from_type(AST, State);
 extract_documentation0({attribute, _Anno, callback, {{CB, A}, _Form}}=AST, State) ->
     State1 = remove_exported_type_info({callback, CB, A}, State),
@@ -956,7 +957,7 @@ extract_user_types(_Else, Acc) ->
 
 extract_documentation_from_type({attribute, Anno, TypeOrOpaque, {TypeName, _TypeDef, TypeArgs}=Types},
                       #docs{docs = Docs, exported_types=ExpTypes}=State)
-  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque ->
+  when TypeOrOpaque =:= type; TypeOrOpaque =:= opaque; TypeOrOpaque =:= nominal ->
    Args = fun_to_varargs(TypeArgs),
    Key =  {type, TypeName, length(TypeArgs)},
 
@@ -979,9 +980,9 @@ add_last_read_user_type(_Anno, {_TypeName, TypeDef, TypeArgs}, State) ->
    Types = extract_user_types([TypeArgs, TypeDef], State),
    set_last_read_user_types(State, Types).
 
-%% NOTE: Terminal elements for the documentation, such as `-type`, `-opaque`, `-callback`,
-%%       and functions always need to reset the state when they finish, so that new
-%%       new AST items start with a clean slate.
+%% NOTE: Terminal elements for the documentation, such as `-type`, `-opaque`,
+%% `-nominal`, `-callback`, and functions always need to reset the state when
+%% they finish, so that new AST items start with a clean slate.
 extract_documentation_from_funs({function, Anno, F, A, [{clause, _, ClauseArgs, _, _}]},
                       #docs{exported_functions = ExpFuns}=State) ->
     case (sets:is_element({F, A}, ExpFuns) orelse State#docs.export_all) of

lib/compiler/src/beam_ssa_dead.erl

@@ -240,7 +240,7 @@ shortcut_3(L, From, Bs0, UnsetVars0, St) ->
                             %% because it refers to a variable defined
                             %% in this block.
                             shortcut_unsafe_br(Br, L, Bs, UnsetVars0, St);
-                        UnsetVars ->
+                        {safe, UnsetVars} ->
                             %% Continue checking whether this br is
                             %% suitable.
                             shortcut_test_br(Br, L, Bs, UnsetVars, St)
@@ -381,16 +381,16 @@ update_unset_vars(L, Is, Br, UnsetVars, #st{skippable=Skippable}) ->
                             %% to the UnsetVars set would not change
                             %% the outcome of the tests in
                             %% is_br_safe/2.
-                            UnsetVars
+                            {safe, UnsetVars}
                     end;
                 #b_br{} ->
-                    UnsetVars
+                    {safe, UnsetVars}
             end;
         false ->
             %% Some variables defined in this block are used by
             %% successors. We must update the set of unset variables.
             SetInThisBlock = [V || #b_set{dst=V} <:- Is],
-            list_set_union(SetInThisBlock, UnsetVars)
+            {safe, list_set_union(SetInThisBlock, UnsetVars)}
     end.
 
 shortcut_two_way(#b_br{succ=Succ,fail=Fail}, From, Bs0, UnsetVars0, St0) ->