beam_ssa_throw: Exceptions may escape modules through funs

lib/compiler/src/beam_ssa_throw.erl

@@ -166,6 +166,21 @@ si_is([#b_set{op=raw_raise,args=[_,_,Stacktrace]} | Is],
 si_is([#b_set{op=build_stacktrace,args=[Stacktrace]} | Is],
       Id, Lbl, Last, Lst, Gst) ->
     si_handler_end(Is, Id, Lbl, Last, Stacktrace, Lst, Gst);
+si_is([#b_set{op=MakeFun,args=[#b_local{}=Callee | _]} | _Is],
+      _Id, _Lbl, _Last, Lst, Gst)
+  when MakeFun =:= make_fun;
+       MakeFun =:= old_make_fun ->
+    #gst{tlh_roots = Roots0} = Gst,
+
+    %% Funs may be called from anywhere which may result in a throw escaping
+    %% the module, so we'll add an unsuitable top-level handler to all funs.
+    Handlers = case gb_trees:lookup(Callee, Roots0) of
+                    {value, Handlers0} -> gb_sets:add(unsuitable, Handlers0);
+                    none -> gb_sets:singleton(unsuitable)
+                end,
+    Roots = gb_trees:enter(Callee, Handlers, Roots0),
+
+    {Lst, Gst#gst{tlh_roots=Roots}};
 si_is([#b_set{op=call,
               dst=Dst,
               args=[#b_remote{mod=#b_literal{val=erlang},

lib/compiler/test/trycatch_SUITE.erl

@@ -31,7 +31,8 @@
          no_return_in_try_block/1,
          expression_export/1,
          throw_opt_crash/1,
-         coverage/1]).
+         coverage/1,
+         throw_opt_funs/1]).
 
 -include_lib("common_test/include/ct.hrl").
 
@@ -50,7 +51,8 @@ groups() ->
        stacktrace,nested_stacktrace,raise,
        no_return_in_try_block,expression_export,
        throw_opt_crash,
-       coverage]}].
+       coverage,
+       throw_opt_funs]}].
 
 
 init_per_suite(Config) ->
@@ -1672,4 +1674,28 @@ bad_class(Config) ->
         _ -> also_bad
     end.
 
+%% GH-7356: Funs weren't considered when checking whether an exception could
+%% escape the module, erroneously triggering the optimization in some cases.
+throw_opt_funs(_Config) ->
+    try throw_opt_funs_1(id(a)) of
+        _ -> unreachable
+    catch
+        _:Val -> a = id(Val)                    %Assertion.
+    end,
+
+    F = id(fun throw_opt_funs_1/1),
+
+    try F(a) of
+        _ -> unreachable
+    catch
+        _:_:Stack -> true = length(Stack) > 0   %Assertion.
+    end,
+
+    ok.
+
+throw_opt_funs_1(a) ->
+    throw(a);
+throw_opt_funs_1(I) ->
+    I.
+
 id(I) -> I.