More C++ compilability work: mrb_obj_alloc void* conversions

One of the biggest set of changes needed to make C++ compile, is that you
can't autoconvert "void*" to a different pointer type without a cast (you
can of course, convert pointers *to* "void*"!)

For the first part, convert the users of "mrb_obj_alloc".  Since it has
to return something, make it RBasic* (that's what mrb_obj_alloc() is
operating on anyway).  This way, even in C you'll get a warning if you
don't cast it.

For places where there are a lot of similar calls to mrb_obj_alloc(),
this can be easily hidden through a macro.  I did this in string.c:
    #define mrb_obj_alloc_string(mrb) ((struct RString *) mrb_obj_alloc((mrb), MRB_TT_STRING, (mrb)->string_class))

I also updated the mrb_object() macro to also return a RBasic* -- my
previous commit changed that from "void*" -> "RObject*", but I figure
it should be consistent with mrb_obj_alloc()

1 files changed, 2 insertions, 2 deletions

diff --git a/src/gc.c b/src/gc.c
index 8f11f1e1d..fde0edfa6 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -242,7 +242,7 @@ mrb_init_heap(mrb_state *mrb)
 #endif
 }
 
-void*
+struct RBasic*
 mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
 {
   struct RBasic *p;
@@ -270,7 +270,7 @@ mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
   p->tt = ttype;
   p->c = cls;
   paint_partial_white(mrb, p);
-  return (void*)p;
+  return p;
 }
 
 static inline void