Add `mrb_get_arg1()` that retrieves single (and only) argument.

`mrb_get_arg1()` raises `ArgumentError` if the method does not receive one
argument.

And replaces all `mrb_get_args(mrb, "o", &arg)` by the new function.

1 files changed, 1 insertions, 3 deletions

diff --git a/mrbgems/mruby-range-ext/src/range.c b/mrbgems/mruby-range-ext/src/range.c
index 36b684fad..2a0b4e97d 100644
--- a/mrbgems/mruby-range-ext/src/range.c
+++ b/mrbgems/mruby-range-ext/src/range.c
@@ -34,12 +34,10 @@ r_lt(mrb_state *mrb, mrb_value a, mrb_value b)
 static mrb_value
 range_cover(mrb_state *mrb, mrb_value range)
 {
-  mrb_value val;
   struct RRange *r = mrb_range_ptr(mrb, range);
+  mrb_value val = mrb_get_arg1(mrb);
   mrb_value beg, end;
 
-  mrb_get_args(mrb, "o", &val);
-
   beg = RANGE_BEG(r);
   end = RANGE_END(r);