Fixed finding variables from `proc` in `binding.eval` failed

Previously the following code did not produce the expected results:
```ruby
bx = binding
block = bx.eval("a = 1; proc { a }")
bx.eval("a = 2")
p block.call  # Expect 2 but return 1 due to a bug
```

The previous implementation of `Binding#eval` evaluated the code and then merged the top layer variables.
This patch will parse and expand the variable space before making a call to `eval`.
This means that the call to `Binding#eval` will do the parsing twice.

In addition, the following changes will be made:
- Make `mrb_parser_foreach_top_variable()`, `mrb_binding_extract_proc()` and `mrb_binding_extract_env()` functions private global functions.
- Remove the `posthook` argument from `mrb_exec_irep()`.
  The `posthook` argument was introduced to implement the `binding` method.
  This patch is unnecessary because it uses a different implementation method.

ref #5362
fixed #5491

1 files changed, 6 insertions, 41 deletions

diff --git a/mrbgems/mruby-eval/src/eval.c b/mrbgems/mruby-eval/src/eval.c
index 66f4d5283..19e4fe2ed 100644
--- a/mrbgems/mruby-eval/src/eval.c
+++ b/mrbgems/mruby-eval/src/eval.c
@@ -9,7 +9,7 @@
 #include <mruby/variable.h>
 
 struct REnv *mrb_env_new(mrb_state *mrb, struct mrb_context *c, mrb_callinfo *ci, int nstacks, mrb_value *stack, struct RClass *tc);
-mrb_value mrb_exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p, mrb_func_t posthook);
+mrb_value mrb_exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p);
 mrb_value mrb_obj_instance_eval(mrb_state *mrb, mrb_value self);
 mrb_value mrb_mod_module_eval(mrb_state*, mrb_value);
 void mrb_codedump_all(mrb_state*, struct RProc*);
@@ -128,44 +128,13 @@ create_proc_from_string(mrb_state *mrb, const char *s, mrb_int len, mrb_value bi
 }
 
 static mrb_value
-exec_irep(mrb_state *mrb, mrb_value self, struct RProc *proc, mrb_func_t posthook)
+exec_irep(mrb_state *mrb, mrb_value self, struct RProc *proc)
 {
   /* no argument passed from eval() */
   mrb->c->ci->argc = 0;
   /* clear block */
   mrb->c->ci->stack[1] = mrb_nil_value();
-  return mrb_exec_irep(mrb, self, proc, posthook);
-}
-
-static void
-eval_merge_lvar(mrb_state *mrb, mrb_irep *irep, struct REnv *env, int num, const mrb_sym *lv, const mrb_value *stack)
-{
-  mrb_assert(mrb->c->stend >= stack + num);
-  mrb_proc_merge_lvar(mrb, irep, env, num, lv, stack);
-}
-
-static mrb_value
-eval_merge_lvar_hook(mrb_state *mrb, mrb_value dummy_self)
-{
-  const mrb_callinfo *orig_ci = &mrb->c->ci[1];
-  const struct RProc *orig_proc = orig_ci->proc;
-  const mrb_irep *orig_irep = orig_proc->body.irep;
-  int orig_nlocals = orig_irep->nlocals;
-
-  if (orig_nlocals > 1) {
-    struct RProc *proc = (struct RProc *)orig_proc->upper;
-    struct REnv *env = MRB_PROC_ENV(orig_proc);
-    eval_merge_lvar(mrb, (mrb_irep *)proc->body.irep, env,
-                    orig_nlocals - 1, orig_irep->lv,
-                    mrb->c->ci->stack + 3 /* hook proc + exc + ret val */);
-  }
-
-  mrb_value exc = mrb->c->ci->stack[1];
-  if (!mrb_nil_p(exc)) {
-    mrb_exc_raise(mrb, exc);
-  }
-
-  return mrb->c->ci->stack[2];
+  return mrb_exec_irep(mrb, self, proc);
 }
 
 static mrb_value
@@ -177,19 +146,15 @@ f_eval(mrb_state *mrb, mrb_value self)
   const char *file = NULL;
   mrb_int line = 1;
   struct RProc *proc;
-  mrb_func_t posthook = NULL;
 
   mrb_get_args(mrb, "s|ozi", &s, &len, &binding, &file, &line);
 
   proc = create_proc_from_string(mrb, s, len, binding, file, line);
   if (!mrb_nil_p(binding)) {
     self = mrb_iv_get(mrb, binding, MRB_SYM(recv));
-    if (mrb_env_p(mrb_iv_get(mrb, binding, MRB_SYM(env)))) {
-      posthook = eval_merge_lvar_hook;
-    }
   }
   mrb_assert(!MRB_PROC_CFUNC_P(proc));
-  return exec_irep(mrb, self, proc, posthook);
+  return exec_irep(mrb, self, proc);
 }
 
 static mrb_value
@@ -209,7 +174,7 @@ f_instance_eval(mrb_state *mrb, mrb_value self)
     MRB_PROC_SET_TARGET_CLASS(proc, mrb_class_ptr(cv));
     mrb_assert(!MRB_PROC_CFUNC_P(proc));
     mrb_vm_ci_target_class_set(mrb->c->ci, mrb_class_ptr(cv));
-    return exec_irep(mrb, self, proc, NULL);
+    return exec_irep(mrb, self, proc);
   }
   else {
     mrb_get_args(mrb, "");
@@ -232,7 +197,7 @@ f_class_eval(mrb_state *mrb, mrb_value self)
     MRB_PROC_SET_TARGET_CLASS(proc, mrb_class_ptr(self));
     mrb_assert(!MRB_PROC_CFUNC_P(proc));
     mrb_vm_ci_target_class_set(mrb->c->ci, mrb_class_ptr(self));
-    return exec_irep(mrb, self, proc, NULL);
+    return exec_irep(mrb, self, proc);
   }
   else {
     mrb_get_args(mrb, "");