Fix calling .arity on Proc with undefined `initialize`

Reported by @bouk

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);
   }

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

src/proc.c

@@ -188,18 +188,13 @@ mrb_proc_call_cfunc(mrb_state *mrb, struct RProc *p, mrb_value self)
   return (p->body.func)(mrb, self);
 }
 
-mrb_code*
-mrb_proc_iseq(mrb_state *mrb, struct RProc *p)
-{
-  return p->body.irep->iseq;
-}
-
 /* 15.2.17.4.2 */
 static mrb_value
 mrb_proc_arity(mrb_state *mrb, mrb_value self)
 {
   struct RProc *p = mrb_proc_ptr(self);
-  mrb_code *iseq = mrb_proc_iseq(mrb, p);
+  struct mrb_irep *irep;
+  mrb_code *iseq;
   mrb_aspec aspec;
   int ma, op, ra, pa, arity;
 
@@ -208,6 +203,12 @@ mrb_proc_arity(mrb_state *mrb, mrb_value self)
     return mrb_fixnum_value(-1);
   }
 
+  irep = p->body.irep;
+  if (!irep) {
+    return mrb_fixnum_value(0);
+  }
+
+  iseq = irep->iseq;
   /* arity is depend on OP_ENTER */
   if (GET_OPCODE(*iseq) != OP_ENTER) {
     return mrb_fixnum_value(0);

test/t/proc.rb

@@ -46,6 +46,17 @@ assert('Proc#arity', '15.2.17.4.2') do
   assert_equal(-1, g)
 end
 
+assert('Proc#arity with unitialized Proc') do
+  begin
+    Proc.alias_method(:original_initialize, :initialize)
+    Proc.remove_method(:initialize)
+    assert_equal 0, Proc.new{|a, b, c| 1}.arity
+  ensure
+    Proc.alias_method(:initialize, :original_initialize)
+    Proc.remove_method(:original_initialize)
+  end
+end
+
 assert('Proc#call', '15.2.17.4.3') do
   a = 0
   b = Proc.new { a += 1 }