From e0f5861a4d2051bc3c944ac382c026c83d41a24a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Pavli=CC=81k?= <david@dpavlik.cz>
Date: Tue, 6 Dec 2022 12:06:09 +0100
Subject: [PATCH] Add support for module_info functions

---
 src/typechecker.erl                   | 45 +++++++++++++++++++++++++--
 test/should_fail/module_info_fail.erl |  7 +++++
 test/should_pass/module_info.erl      | 21 +++++++++++++
 3 files changed, 71 insertions(+), 2 deletions(-)
 create mode 100644 test/should_fail/module_info_fail.erl
 create mode 100644 test/should_pass/module_info.erl

diff --git a/src/typechecker.erl b/src/typechecker.erl
index 1d736ae7..85848620 100644
--- a/src/typechecker.erl
+++ b/src/typechecker.erl
@@ -1658,6 +1658,10 @@ do_type_check_expr(Env, {call, _, {atom, _, TypeOp}, [Expr, {string, _, TypeStr}
 do_type_check_expr(Env, {call, _, {atom, _, record_info}, [_, _]} = Call) ->
     Ty = get_record_info_type(Call, Env),
     {Ty, Env, constraints:empty()};
+do_type_check_expr(Env, {call, P, {remote, _, _Mod, {atom, _, module_info}} = Name, Args}) ->
+    Arity = arity(length(Args)),
+    FunTy = get_module_info_type(Arity),
+    type_check_call_ty(Env, expect_fun_type(Env, FunTy, Arity), Args, {Name, P, FunTy});
 do_type_check_expr(Env, {call, P, Name, Args}) ->
     Arity = arity(length(Args)),
     {FunTy, VarBinds1, Cs1} = type_check_fun(Env, Name, Arity),
@@ -2543,6 +2547,11 @@ do_type_check_expr_in(Env, ResTy, {call, _, {atom, _, record_info}, [_, _]} = Ca
         false ->
             throw(type_error(Call, ResTy, Ty))
     end;
+do_type_check_expr_in(Env, ResTy, {call, P, {remote, _, _Mod, {atom, _, module_info}} = Name, Args} = Call) ->
+    Arity = arity(length(Args)),
+    FunTy = get_module_info_type(Arity),
+    type_check_call(Env, ResTy, Call, expect_fun_type(Env, FunTy, Arity),
+                    Args, {P, Name, FunTy});
 do_type_check_expr_in(Env, ResTy, {call, P, Name, Args} = OrigExpr) ->
     Arity = arity(length(Args)),
     {FunTy, VarBinds, Cs} = type_check_fun(Env, Name, Arity),
@@ -4944,9 +4953,16 @@ type_record(Name, Fields) ->
 type_field_type(Name, Type) ->
     {type, erl_anno:new(0), field_type, [{atom, erl_anno:new(0), Name}, Type]}.
 
+-spec type_fun([type()], type()) -> type().
+type_fun(Args, ResTy) ->
+    type('fun', [type(product, Args), ResTy]).
+
 type_fun(Arity) ->
-    Args = [{type, erl_anno:new(0), any, []} || _ <- lists:seq(1, Arity)],
-    {type, erl_anno:new(0), 'fun', [{type, erl_anno:new(0), product, Args}, {type, erl_anno:new(0), any, []}]}.
+    Args = [type(any) || _ <- lists:seq(1, Arity)],
+    type_fun(Args, type(any)).
+
+type_atom(Name) ->
+    {atom, erl_anno:new(0), Name}.
 
 is_power_of_two(0) -> false;
 is_power_of_two(1) -> true;
@@ -5095,6 +5111,31 @@ record_field_types(Fields) ->
                       {Name, Type}
               end, Fields).
 
+% Helper returning the type of module_info/0 and module_info/1 functions
+-spec get_module_info_type(arity()) -> fun_ty().
+get_module_info_type(0) ->
+    Options = get_module_info_options(),
+    DefaultKeys = [module, attributes, compile, exports, md5, native],
+    DefaultOpts = lists:filter(fun ({Key, _}) -> lists:member(Key, DefaultKeys) end, Options),
+    TupleTys = lists:map(fun ({Key, Ty}) -> type(tuple, [type_atom(Key), Ty]) end, DefaultOpts),
+    type_fun([], type(list, [type(union, TupleTys)]));
+get_module_info_type(1) ->
+    Options = get_module_info_options(),
+    lists:map(fun ({Key, Type}) -> type_fun([type_atom(Key)], Type) end, Options).
+
+-spec get_module_info_options() -> #{atom() => type()}.
+get_module_info_options() ->
+    [
+        {module, type(module)},
+        {attributes, type(list, [type(tuple, [type(atom), type(any)])])},
+        {compile, type(list, [type(tuple, [type(any), type(any)])])},
+        {md5, type(binary)},
+        {exports, type(list, [type(tuple, [type(atom), type(arity)])])},
+        {functions, type(list, [type(tuple, [type(atom), type(arity)])])},
+        {nifs, type(list, [type(tuple, [type(atom), type(arity)])])},
+        {native, type(boolean)}
+    ].
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%% Main entry point
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/test/should_fail/module_info_fail.erl b/test/should_fail/module_info_fail.erl
new file mode 100644
index 00000000..87063856
--- /dev/null
+++ b/test/should_fail/module_info_fail.erl
@@ -0,0 +1,7 @@
+-module(module_info_fail).
+
+-compile([export_all, nowarn_export_all]).
+
+-spec md5() -> atom().
+md5() ->
+    erlang:module_info(md5).
\ No newline at end of file
diff --git a/test/should_pass/module_info.erl b/test/should_pass/module_info.erl
new file mode 100644
index 00000000..d4d1c028
--- /dev/null
+++ b/test/should_pass/module_info.erl
@@ -0,0 +1,21 @@
+-module(module_info).
+
+-compile([export_all, nowarn_export_all]).
+
+-spec nullary_direct() -> [{atom(), atom() | list() | binary()}].
+nullary_direct() ->
+    erlang:module_info().
+
+-spec nullary_var() -> [{atom(), any()}].
+nullary_var() ->
+    I = erlang:module_info(),
+    I.
+
+-spec unary_direct() -> binary().
+unary_direct() ->
+    erlang:module_info(md5).
+
+-spec unary_var() -> atom().
+unary_var() ->
+    I = erlang:module_info(module),
+    I.
\ No newline at end of file