File 1891-erts-Fix-module-name-reported-by-fun_info-... of Package erlang

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File 1891-erts-Fix-module-name-reported-by-fun_info-1-2-on-unl.patch of Package erlang (Revision 57cf7c87cb80e2aaaf3f20327bf57529)

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From d5eecebad9ad6868535ec85621b99dda3115211d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Wed, 10 Nov 2021 11:33:49 +0100
Subject: [PATCH] erts: Fix module name reported by fun_info/1,2 on unloaded
 funs

---
 erts/emulator/beam/erl_bif_info.c             | 21 +++++++++++---
 erts/emulator/beam/erl_fun.c                  |  3 +-
 .../call_purged_fun_tester.erl                | 29 +++++++++++++++----
 3 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 929f06e1ef..c1352c2ba8 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -3564,7 +3564,9 @@ fun_info_2(BIF_ALIST_2)
         hp = HAlloc(p, 3);
         break;
     case am_module:
-        val = mfa->module;
+        /* Unloaded funs must report their module even though we can't find
+         * their full MFA. */
+        val = (mfa != NULL) ? mfa->module : fe->module;
         hp = HAlloc(p, 3);
         break;
     case am_new_index:
@@ -3612,8 +3614,9 @@ fun_info_2(BIF_ALIST_2)
         hp = HAlloc(p, 3);
         break;
     case am_name:
+        /* Name must be `[]` for unloaded funs. */
+        val = (mfa != NULL) ? mfa->function : NIL;
         hp = HAlloc(p, 3);
-        val = mfa->function;
         break;
     default:
         BIF_ERROR(p, BADARG);
@@ -3627,22 +3630,32 @@ fun_info_mfa_1(BIF_ALIST_1)
 {
     Process* p = BIF_P;
     Eterm fun = BIF_ARG_1;
-    Eterm* hp;
 
     if (is_any_fun(fun)) {
         const ErtsCodeMFA *mfa;
         ErlFunThing* funp;
+        Eterm* hp;
 
         funp = (ErlFunThing *) fun_val(fun);
+        hp = HAlloc(p, 4);
 
         if (is_local_fun(funp)) {
             mfa = erts_get_fun_mfa(funp->entry.fun);
+
+            if (mfa == NULL) {
+                /* Unloaded funs must report their module even though we can't
+                 * find their full MFA, and their function name must be
+                 * `[]`. */
+                BIF_RET(TUPLE3(hp,
+                               funp->entry.fun->module,
+                               NIL,
+                               make_small(funp->arity)));
+            }
         } else {
             ASSERT(is_external_fun(funp) && funp->next == NULL);
             mfa = &(funp->entry.exp)->info.mfa;
         }
 
-        hp = HAlloc(p, 4);
         BIF_RET(TUPLE3(hp,
                        mfa->module,
                        mfa->function,
diff --git a/erts/emulator/beam/erl_fun.c b/erts/emulator/beam/erl_fun.c
index 7c288d8c14..629cb15adb 100644
--- a/erts/emulator/beam/erl_fun.c
+++ b/erts/emulator/beam/erl_fun.c
@@ -131,14 +131,13 @@ erts_put_fun_entry2(Eterm mod, int old_uniq, int old_index,
 }
 
 const ErtsCodeMFA *erts_get_fun_mfa(const ErlFunEntry *fe) {
-    static const ErtsCodeMFA unloaded_mfa = {NIL, NIL, ERTS_UINT_MAX};
     ErtsCodePtr address = fe->dispatch.addresses[0];
 
     if (address != beam_unloaded_fun) {
         return erts_find_function_from_pc(address);
     }
 
-    return &unloaded_mfa;
+    return NULL;
 }
 
 void erts_set_fun_code(ErlFunEntry *fe, ErtsCodePtr address) {
diff --git a/erts/emulator/test/code_SUITE_data/call_purged_fun_tester.erl b/erts/emulator/test/code_SUITE_data/call_purged_fun_tester.erl
index 6d74b63863..5ed5214c94 100644
--- a/erts/emulator/test/code_SUITE_data/call_purged_fun_tester.erl
+++ b/erts/emulator/test/code_SUITE_data/call_purged_fun_tester.erl
@@ -41,6 +41,19 @@ do_it(Priv, Data, Type, Opts) ->
 			false
 		end,
 
+    %% fun_info/1,2 must behave as documented on purged funs.
+    FunInfoBefore = fun(F) ->
+                            {module, my_code_test2} = erlang:fun_info(F, module),
+                            {name, []} = erlang:fun_info(F, name),
+                            {arity, 1} = erlang:fun_info(F, arity)
+                    end,
+    FunInfoAfter = fun(F) ->
+                           {module, my_code_test2} = erlang:fun_info(F, module),
+                           {name, Name} = erlang:fun_info(F, name),
+                           true = is_atom(Name),
+                           {arity, 1} = erlang:fun_info(F, arity)
+                   end,
+
     true = erlang:delete_module(my_code_test2),
 
     ok = receive {P0, "going to sleep"} -> ok
@@ -51,7 +64,9 @@ do_it(Priv, Data, Type, Opts) ->
 
     {P1, M1} = spawn_monitor(fun () ->
                                      [{my_fun,F}] = ets:lookup(T, my_fun),
+                                     FunInfoBefore(F),
                                      4712 = F(1),
+                                     FunInfoAfter(F),
                                      exit(completed)
                              end),
 
@@ -64,14 +79,18 @@ do_it(Priv, Data, Type, Opts) ->
 
     {P2, M2} = spawn_monitor(fun () ->
                                      [{my_fun,F}] = ets:lookup(T, my_fun),
+                                     FunInfoBefore(F),
                                      4713 = F(2),
+                                     FunInfoAfter(F),
                                      exit(completed)
-			     end),
+                             end),
     {P3, M3} = spawn_monitor(fun () ->
-				     [{my_fun,F}] = ets:lookup(T, my_fun),
-				     4714 = F(3),
-				     exit(completed)
-			     end),
+                                     [{my_fun,F}] = ets:lookup(T, my_fun),
+                                     FunInfoBefore(F),
+                                     4714 = F(3),
+                                     FunInfoAfter(F),
+                                     exit(completed)
+                             end),
 
     ok = wait_until(fun () ->
 			    {status, suspended}
-- 
2.31.1

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File 1891-erts-Fix-module-name-reported-by-fun_info-1-2-on-unl.patch of Package erlang (Revision 57cf7c87cb80e2aaaf3f20327bf57529)

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