Fix calling .arity on Proc with undefined `initialize`

Reported by @bouk

2 files changed, 14 insertions, 0 deletions

diff --git a/mrbgems/mruby-proc-ext/src/proc.c b/mrbgems/mruby-proc-ext/src/proc.c
index c8c8f1aa1..34f6230dc 100644
--- a/mrbgems/mruby-proc-ext/src/proc.c
+++ b/mrbgems/mruby-proc-ext/src/proc.c
@@ -114,6 +114,9 @@ mrb_proc_parameters(mrb_state *mrb, mrb_value self)
     // TODO cfunc aspec is not implemented yet
     return mrb_ary_new(mrb);
   }
+  if (!irep) {
+    return mrb_ary_new(mrb);
+  }
   if (!irep->lv) {
     return mrb_ary_new(mrb);
   }
diff --git a/mrbgems/mruby-proc-ext/test/proc.rb b/mrbgems/mruby-proc-ext/test/proc.rb
index 75e11dd93..7a078aabf 100644
--- a/mrbgems/mruby-proc-ext/test/proc.rb
+++ b/mrbgems/mruby-proc-ext/test/proc.rb
@@ -58,6 +58,17 @@ assert('Proc#parameters') do
   assert_equal([[:req, :a], [:req, :b], [:opt, :c], [:opt, :d], [:rest, :e], [:req, :f], [:req, :g], [:block, :h]], lambda {|a,b,c=:c,d=:d,*e,f,g,&h|}.parameters)
 end
 
+assert('Proc#parameters with uninitialized Proc') do
+  begin
+    Proc.alias_method(:original_initialize, :initialize)
+    Proc.remove_method(:initialize)
+    assert_equal [], Proc.new{|a, b, c| 1}.parameters
+  ensure
+    Proc.alias_method(:initialize, :original_initialize)
+    Proc.remove_method(:original_initialize)
+  end
+end
+
 assert('Proc#to_proc') do
   proc = Proc.new {}
   assert_equal proc, proc.to_proc