Do no use return values from `mrb_ensure_` functions.

They return the checking argument without modification, so the values
are already there. Maybe we should change the return type to `void` but
keep them unchanged for compatibility.

mrbgems/mruby-io/src/file.c

@@ -116,14 +116,14 @@ static mrb_value
 mrb_file_s_unlink(mrb_state *mrb, mrb_value obj)
 {
   const mrb_value *argv;
-  mrb_value pathv;
   mrb_int argc, i;
   char *path;
 
   mrb_get_args(mrb, "*", &argv, &argc);
   for (i = 0; i < argc; i++) {
     const char *utf8_path;
-    pathv = mrb_ensure_string_type(mrb, argv[i]);
+    mrb_value pathv = argv[i];
+    mrb_ensure_string_type(mrb, pathv);
     utf8_path = RSTRING_CSTR(mrb, pathv);
     path = mrb_locale_from_utf8(utf8_path, -1);
     if (UNLINK(path) < 0) {

mrbgems/mruby-kernel-ext/src/kernel.c

@@ -202,7 +202,8 @@ mrb_f_hash(mrb_state *mrb, mrb_value self)
   if (mrb_nil_p(arg) || (mrb_array_p(arg) && RARRAY_LEN(arg) == 0)) {
     return mrb_hash_new(mrb);
   }
-  return mrb_ensure_hash_type(mrb, arg);
+  mrb_ensure_hash_type(mrb, arg);
+  return arg;
 }
 
 void

mrbgems/mruby-string-ext/src/string.c

@@ -195,14 +195,14 @@ static mrb_value
 mrb_str_start_with(mrb_state *mrb, mrb_value self)
 {
   const mrb_value *argv;
-  mrb_value sub;
   mrb_int argc, i;
   mrb_get_args(mrb, "*", &argv, &argc);
 
   for (i = 0; i < argc; i++) {
     size_t len_l, len_r;
     int ai = mrb_gc_arena_save(mrb);
-    sub = mrb_ensure_string_type(mrb, argv[i]);
+    mrb_value sub = argv[i];
+    mrb_ensure_string_type(mrb, sub);
     mrb_gc_arena_restore(mrb, ai);
     len_l = RSTRING_LEN(self);
     len_r = RSTRING_LEN(sub);
@@ -225,14 +225,14 @@ static mrb_value
 mrb_str_end_with(mrb_state *mrb, mrb_value self)
 {
   const mrb_value *argv;
-  mrb_value sub;
   mrb_int argc, i;
   mrb_get_args(mrb, "*", &argv, &argc);
 
   for (i = 0; i < argc; i++) {
     size_t len_l, len_r;
     int ai = mrb_gc_arena_save(mrb);
-    sub = mrb_ensure_string_type(mrb, argv[i]);
+    mrb_value sub = argv[i];
+    mrb_ensure_string_type(mrb, sub);
     mrb_gc_arena_restore(mrb, ai);
     len_l = RSTRING_LEN(self);
     len_r = RSTRING_LEN(sub);

src/class.c

@@ -2379,7 +2379,7 @@ mrb_mod_const_get(mrb_state *mrb, mrb_value mod)
   }
 
   /* const get with class path string */
-  path = mrb_ensure_string_type(mrb, path);
+  mrb_ensure_string_type(mrb, path);
   ptr = RSTRING_PTR(path);
   len = RSTRING_LEN(path);
   off = 0;

src/vm.c

@@ -2671,7 +2671,8 @@ RETRY_TRY_BLOCK:
       int i;
       int lim = a+b*2+1;
 
-      hash = mrb_ensure_hash_type(mrb, regs[a]);
+      hash = regs[a];
+      mrb_ensure_hash_type(mrb, hash);
       for (i=a+1; i<lim; i+=2) {
         mrb_hash_set(mrb, hash, regs[i], regs[i+1]);
       }
@@ -2679,8 +2680,9 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
     CASE(OP_HASHCAT, B) {
-      mrb_value hash = mrb_ensure_hash_type(mrb, regs[a]);
+      mrb_value hash = regs[a];
 
+      mrb_ensure_hash_type(mrb, hash);
       mrb_hash_merge(mrb, hash, regs[a+1]);
       mrb_gc_arena_restore(mrb, ai);
       NEXT;