Use new specifiers/modifiers of `mrb_vfromat()`

The binary sizes (gems are only `mruby-bin-mruby`) are reduced slightly in
my environment than before the introduction of new specifiers/modifiers
(5116789a) with this change.

  ------------+-------------------+-------------------+--------
   BINARY     | BEFORE (5116789a) |   AFTER (This PR) |  RATIO
  ------------+-------------------+-------------------+--------
   mruby      |      593416 bytes |      593208 bytes | -0.04%
   libmruby.a |      769048 bytes |      767264 bytes | -0.23%
  ------------+-------------------+-------------------+--------

BTW, I accidentally changed `tasks/toolchains/visualcpp.rake` at #4613,
so I put it back.

17 files changed, 85 insertions, 108 deletions

diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index ed8fc3150..5cade970c 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -2373,7 +2373,7 @@ codegen(codegen_scope *s, node *tree, int val)
       mrb_value str;
       int sym;
 
-      str = mrb_format(mrb, "$%S", mrb_fixnum_value(nint(tree)));
+      str = mrb_format(mrb, "$%d", nint(tree));
       sym = new_sym(s, mrb_intern_str(mrb, str));
       genop_2(s, OP_GETGV, cursp(), sym);
       push();
diff --git a/mrbgems/mruby-compiler/core/parse.y b/mrbgems/mruby-compiler/core/parse.y
index f6d543c5d..3a55c8e70 100644
--- a/mrbgems/mruby-compiler/core/parse.y
+++ b/mrbgems/mruby-compiler/core/parse.y
@@ -3831,7 +3831,7 @@ backref_error(parser_state *p, node *n)
     yyerror_c(p, "can't set variable $", (char)intn(n->cdr));
   }
   else {
-    mrb_bug(p->mrb, "Internal error in backref_error() : n=>car == %S", mrb_fixnum_value(c));
+    mrb_bug(p->mrb, "Internal error in backref_error() : n=>car == %d", c);
   }
 }
 
diff --git a/mrbgems/mruby-complex/src/complex.c b/mrbgems/mruby-complex/src/complex.c
index aa2afc2ce..a87b95dea 100644
--- a/mrbgems/mruby-complex/src/complex.c
+++ b/mrbgems/mruby-complex/src/complex.c
@@ -101,7 +101,7 @@ complex_to_f(mrb_state *mrb, mrb_value self)
   struct mrb_complex *p = complex_ptr(mrb, self);
 
   if (p->imaginary != 0) {
-    mrb_raisef(mrb, E_RANGE_ERROR, "can't convert %S into Float", self);
+    mrb_raisef(mrb, E_RANGE_ERROR, "can't convert %v into Float", self);
   }
 
   return mrb_float_value(mrb, p->real);
@@ -113,7 +113,7 @@ complex_to_i(mrb_state *mrb, mrb_value self)
   struct mrb_complex *p = complex_ptr(mrb, self);
 
   if (p->imaginary != 0) {
-    mrb_raisef(mrb, E_RANGE_ERROR, "can't convert %S into Float", self);
+    mrb_raisef(mrb, E_RANGE_ERROR, "can't convert %v into Float", self);
   }
   return mrb_int_value(mrb, p->real);
 }
diff --git a/mrbgems/mruby-eval/src/eval.c b/mrbgems/mruby-eval/src/eval.c
index 30534aaec..e8f1d3e95 100644
--- a/mrbgems/mruby-eval/src/eval.c
+++ b/mrbgems/mruby-eval/src/eval.c
@@ -254,15 +254,15 @@ create_proc_from_string(mrb_state *mrb, char *s, mrb_int len, mrb_value binding,
     mrb_value str;
 
     if (file) {
-      str = mrb_format(mrb, " file %S line %S: %S",
-                       mrb_str_new_cstr(mrb, file),
-                       mrb_fixnum_value(p->error_buffer[0].lineno),
-                       mrb_str_new_cstr(mrb, p->error_buffer[0].message));
+      str = mrb_format(mrb, "file %s line %d: %s",
+                       file,
+                       p->error_buffer[0].lineno,
+                       p->error_buffer[0].message);
     }
     else {
-      str = mrb_format(mrb, " line %S: %S",
-                       mrb_fixnum_value(p->error_buffer[0].lineno),
-                       mrb_str_new_cstr(mrb, p->error_buffer[0].message));
+      str = mrb_format(mrb, "line %d: %s",
+                       p->error_buffer[0].lineno,
+                       p->error_buffer[0].message);
     }
     mrb_parser_free(p);
     mrbc_context_free(mrb, cxt);
diff --git a/mrbgems/mruby-io/src/file.c b/mrbgems/mruby-io/src/file.c
index 243f634b4..5e6c849f0 100644
--- a/mrbgems/mruby-io/src/file.c
+++ b/mrbgems/mruby-io/src/file.c
@@ -146,7 +146,7 @@ mrb_file_s_rename(mrb_state *mrb, mrb_value obj)
 #endif
     mrb_locale_free(src);
     mrb_locale_free(dst);
-    mrb_sys_fail(mrb, RSTRING_PTR(mrb_format(mrb, "(%S, %S)", from, to)));
+    mrb_sys_fail(mrb, RSTRING_PTR(mrb_format(mrb, "(%v, %v)", from, to)));
   }
   mrb_locale_free(src);
   mrb_locale_free(dst);
@@ -307,7 +307,7 @@ mrb_file__gethome(mrb_state *mrb, mrb_value klass)
     }
     home = pwd->pw_dir;
     if (!mrb_file_is_absolute_path(home)) {
-      mrb_raisef(mrb, E_ARGUMENT_ERROR, "non-absolute home of ~%S", username);
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "non-absolute home of ~%v", username);
     }
   }
   home = mrb_locale_from_utf8(home, -1);
@@ -398,7 +398,7 @@ mrb_file_s_symlink(mrb_state *mrb, mrb_value klass)
   if (symlink(src, dst) == -1) {
     mrb_locale_free(src);
     mrb_locale_free(dst);
-    mrb_sys_fail(mrb, mrb_str_to_cstr(mrb, mrb_format(mrb, "(%S, %S)", from, to)));
+    mrb_sys_fail(mrb, RSTRING_PTR(mrb_format(mrb, "(%v, %v)", from, to)));
   }
   mrb_locale_free(src);
   mrb_locale_free(dst);
diff --git a/mrbgems/mruby-io/src/io.c b/mrbgems/mruby-io/src/io.c
index 99441f16b..a0b6c6780 100644
--- a/mrbgems/mruby-io/src/io.c
+++ b/mrbgems/mruby-io/src/io.c
@@ -127,7 +127,7 @@ mrb_io_modestr_to_flags(mrb_state *mrb, const char *mode)
       flags |= FMODE_WRITABLE | FMODE_APPEND | FMODE_CREATE;
       break;
     default:
-      mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %S", mrb_str_new_cstr(mrb, mode));
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %s", mode);
   }
 
   while (*m) {
@@ -141,7 +141,7 @@ mrb_io_modestr_to_flags(mrb_state *mrb, const char *mode)
       case ':':
         /* XXX: PASSTHROUGH*/
       default:
-        mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %S", mrb_str_new_cstr(mrb, mode));
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "illegal access mode %s", mode);
     }
   }
 
@@ -191,8 +191,7 @@ mrb_fd_cloexec(mrb_state *mrb, int fd)
 
   flags = fcntl(fd, F_GETFD);
   if (flags == -1) {
-    mrb_bug(mrb, "mrb_fd_cloexec: fcntl(%S, F_GETFD) failed: %S",
-      mrb_fixnum_value(fd), mrb_fixnum_value(errno));
+    mrb_bug(mrb, "mrb_fd_cloexec: fcntl(%d, F_GETFD) failed: %d", fd, errno);
   }
   if (fd <= 2) {
     flags2 = flags & ~FD_CLOEXEC; /* Clear CLOEXEC for standard file descriptors: 0, 1, 2. */
@@ -202,8 +201,7 @@ mrb_fd_cloexec(mrb_state *mrb, int fd)
   }
   if (flags != flags2) {
     if (fcntl(fd, F_SETFD, flags2) == -1) {
-      mrb_bug(mrb, "mrb_fd_cloexec: fcntl(%S, F_SETFD, %S) failed: %S",
-        mrb_fixnum_value(fd), mrb_fixnum_value(flags2), mrb_fixnum_value(errno));
+      mrb_bug(mrb, "mrb_fd_cloexec: fcntl(%d, F_SETFD, %d) failed: %d", fd, flags2, errno);
     }
   }
 #endif
@@ -381,7 +379,7 @@ mrb_io_s_popen(mrb_state *mrb, mrb_value klass)
       CloseHandle(ifd[1]);
       CloseHandle(ofd[0]);
       CloseHandle(ofd[1]);
-      mrb_raisef(mrb, E_IO_ERROR, "command not found: %S", cmd);
+      mrb_raisef(mrb, E_IO_ERROR, "command not found: %v", cmd);
     }
     CloseHandle(pi.hThread);
     CloseHandle(ifd[0]);
@@ -494,7 +492,7 @@ mrb_io_s_popen(mrb_state *mrb, mrb_value klass)
           close(fd);
         }
         mrb_proc_exec(pname);
-        mrb_raisef(mrb, E_IO_ERROR, "command not found: %S", cmd);
+        mrb_raisef(mrb, E_IO_ERROR, "command not found: %v", cmd);
         _exit(127);
       }
       result = mrb_nil_value();
@@ -783,9 +781,7 @@ reopen:
       }
     }
 
-    emsg = mrb_format(mrb, "open %S", mrb_str_new_cstr(mrb, pathname));
-    mrb_str_modify(mrb, mrb_str_ptr(emsg));
-    mrb_sys_fail(mrb, RSTRING_PTR(emsg));
+    mrb_sys_fail(mrb, RSTRING_PTR(mrb_format(mrb, "open %s", pathname)));
   }
   mrb_locale_free(fname);
 
@@ -1068,7 +1064,7 @@ mrb_io_s_select(mrb_state *mrb, mrb_value klass)
   mrb_get_args(mrb, "*", &argv, &argc);
 
   if (argc < 1 || argc > 4) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%S for 1..4)", mrb_fixnum_value(argc));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%i for 1..4)", argc);
   }
 
   timeout = mrb_nil_value();
diff --git a/mrbgems/mruby-io/test/mruby_io_test.c b/mrbgems/mruby-io/test/mruby_io_test.c
index 3312d6c7e..2c8a75fc9 100644
--- a/mrbgems/mruby-io/test/mruby_io_test.c
+++ b/mrbgems/mruby-io/test/mruby_io_test.c
@@ -136,9 +136,9 @@ mrb_io_test_io_setup(mrb_state *mrb, mrb_value self)
   sun0.sun_family = AF_UNIX;
   snprintf(sun0.sun_path, sizeof(sun0.sun_path), "%s", socketname);
   if (bind(fd3, (struct sockaddr *)&sun0, sizeof(sun0)) == -1) {
-    mrb_raisef(mrb, E_RUNTIME_ERROR, "can't bind AF_UNIX socket to %S: %S",
-               mrb_str_new_cstr(mrb, sun0.sun_path),
-               mrb_fixnum_value(errno));
+    mrb_raisef(mrb, E_RUNTIME_ERROR, "can't bind AF_UNIX socket to %s: %d",
+               sun0.sun_path,
+               errno);
   }
   close(fd3);
 #endif
diff --git a/mrbgems/mruby-kernel-ext/src/kernel.c b/mrbgems/mruby-kernel-ext/src/kernel.c
index 8e7e03c56..376751e10 100644
--- a/mrbgems/mruby-kernel-ext/src/kernel.c
+++ b/mrbgems/mruby-kernel-ext/src/kernel.c
@@ -31,22 +31,21 @@ mrb_f_caller(mrb_state *mrb, mrb_value self)
         }
       }
       else {
-        v = mrb_to_int(mrb, v);
-        lev = mrb_fixnum(v);
+        lev = mrb_int(mrb, v);
         if (lev < 0) {
-          mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative level (%S)", v);
+          mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative level (%v)", v);
         }
         n = bt_len - lev;
       }
       break;
     case 2:
-      lev = mrb_fixnum(mrb_to_int(mrb, v));
-      n = mrb_fixnum(mrb_to_int(mrb, length));
+      lev = mrb_int(mrb, v);
+      n = mrb_int(mrb, length);
       if (lev < 0) {
-        mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative level (%S)", v);
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative level (%v)", v);
       }
       if (n < 0) {
-        mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative size (%S)", length);
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative size (%v)", length);
       }
       break;
     default:
diff --git a/mrbgems/mruby-math/src/math.c b/mrbgems/mruby-math/src/math.c
index c6d4ca414..88b33771b 100644
--- a/mrbgems/mruby-math/src/math.c
+++ b/mrbgems/mruby-math/src/math.c
@@ -18,8 +18,7 @@ domain_error(mrb_state *mrb, const char *func)
 {
   struct RClass *math = mrb_module_get(mrb, "Math");
   struct RClass *domainerror = mrb_class_get_under(mrb, math, "DomainError");
-  mrb_value str = mrb_str_new_cstr(mrb, func);
-  mrb_raisef(mrb, domainerror, "Numerical argument is out of domain - %S", str);
+  mrb_raisef(mrb, domainerror, "Numerical argument is out of domain - %s", func);
 }
 
 /* math functions not provided by Microsoft Visual C++ 2012 or older */
diff --git a/mrbgems/mruby-metaprog/src/metaprog.c b/mrbgems/mruby-metaprog/src/metaprog.c
index 62daa5227..97f53051f 100644
--- a/mrbgems/mruby-metaprog/src/metaprog.c
+++ b/mrbgems/mruby-metaprog/src/metaprog.c
@@ -414,7 +414,7 @@ check_cv_name_sym(mrb_state *mrb, mrb_sym id)
   mrb_int len;
   const char *name = mrb_sym2name_len(mrb, id, &len);
   if (!cv_name_p(mrb, name, len)) {
-    mrb_name_error(mrb, id, "'%S' is not allowed as a class variable name", mrb_sym2str(mrb, id));
+    mrb_name_error(mrb, id, "'%n' is not allowed as a class variable name", id);
   }
 }
 
@@ -454,12 +454,10 @@ mrb_mod_remove_cvar(mrb_state *mrb, mrb_value mod)
   if (!mrb_undef_p(val)) return val;
 
   if (mrb_cv_defined(mrb, mod, id)) {
-    mrb_name_error(mrb, id, "cannot remove %S for %S",
-                   mrb_sym2str(mrb, id), mod);
+    mrb_name_error(mrb, id, "cannot remove %n for %v", id, mod);
   }
 
-  mrb_name_error(mrb, id, "class variable %S not defined for %S",
-                 mrb_sym2str(mrb, id), mod);
+  mrb_name_error(mrb, id, "class variable %n not defined for %v", id, mod);
 
  /* not reached */
  return mrb_nil_value();
@@ -622,8 +620,7 @@ remove_method(mrb_state *mrb, mrb_value mod, mrb_sym mid)
     }
   }
 
-  mrb_name_error(mrb, mid, "method '%S' not defined in %S",
-                 mrb_sym2str(mrb, mid), mod);
+  mrb_name_error(mrb, mid, "method '%n' not defined in %v", mid, mod);
 }
 
 /* 15.2.2.4.41 */
diff --git a/mrbgems/mruby-method/src/method.c b/mrbgems/mruby-method/src/method.c
index d94db1cb2..b5050368d 100644
--- a/mrbgems/mruby-method/src/method.c
+++ b/mrbgems/mruby-method/src/method.c
@@ -29,8 +29,7 @@ unbound_method_bind(mrb_state *mrb, mrb_value self)
         if (mrb_type(owner) == MRB_TT_SCLASS) {
           mrb_raise(mrb, E_TYPE_ERROR, "singleton method called for a different object");
         } else {
-          const char *s = mrb_class_name(mrb, mrb_class_ptr(owner));
-          mrb_raisef(mrb, E_TYPE_ERROR, "bind argument must be an instance of %S", mrb_str_new_static(mrb, s, strlen(s)));
+          mrb_raisef(mrb, E_TYPE_ERROR, "bind argument must be an instance of %v", owner);
         }
   }
   me = method_object_alloc(mrb, mrb_class_get(mrb, "Method"));
@@ -289,7 +288,6 @@ static void
 mrb_search_method_owner(mrb_state *mrb, struct RClass *c, mrb_value obj, mrb_sym name, struct RClass **owner, struct RProc **proc, mrb_bool unbound)
 {
   mrb_value ret;
-  const char *s;
 
   *owner = c;
   *proc = method_search_vm(mrb, owner, name);
@@ -313,13 +311,7 @@ mrb_search_method_owner(mrb_state *mrb, struct RClass *c, mrb_value obj, mrb_sym
   return;
 
 name_error:
-  s = mrb_class_name(mrb, c);
-  mrb_raisef(
-    mrb, E_NAME_ERROR,
-    "undefined method '%S' for class '%S'",
-    mrb_sym2str(mrb, name),
-    mrb_str_new_static(mrb, s, strlen(s))
-  );
+  mrb_raisef(mrb, E_NAME_ERROR, "undefined method '%n' for class '%C'", name, c);
 }
 
 static mrb_value
diff --git a/mrbgems/mruby-pack/src/pack.c b/mrbgems/mruby-pack/src/pack.c
index 9f091194b..159ba09ac 100644
--- a/mrbgems/mruby-pack/src/pack.c
+++ b/mrbgems/mruby-pack/src/pack.c
@@ -529,8 +529,8 @@ utf8_to_uv(mrb_state *mrb, const char *p, long *lenp)
     mrb_raise(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character");
   }
   if (n > *lenp) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character (expected %S bytes, given %S bytes)",
-               mrb_fixnum_value(n), mrb_fixnum_value(*lenp));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed UTF-8 character (expected %d bytes, given %d bytes)",
+               n, *lenp);
   }
   *lenp = n--;
   if (n != 0) {
@@ -976,7 +976,7 @@ alias:
       case 4: t = 'L'; goto alias;
       case 8: t = 'Q'; goto alias;
       default:
-        mrb_raisef(mrb, E_RUNTIME_ERROR, "mruby-pack does not support sizeof(int) == %S", mrb_fixnum_value(sizeof(int)));
+        mrb_raisef(mrb, E_RUNTIME_ERROR, "mruby-pack does not support sizeof(int) == %d", (int)sizeof(int));
     }
     break;
   case 'i':
@@ -985,7 +985,7 @@ alias:
       case 4: t = 'l'; goto alias;
       case 8: t = 'q'; goto alias;
       default:
-        mrb_raisef(mrb, E_RUNTIME_ERROR, "mruby-pack does not support sizeof(int) == %S", mrb_fixnum_value(sizeof(int)));
+        mrb_raisef(mrb, E_RUNTIME_ERROR, "mruby-pack does not support sizeof(int) == %d", (int)sizeof(int));
     }
     break;
   case 'L':
@@ -1086,8 +1086,7 @@ alias:
       count = -1;
     } else if (ch == '_' || ch == '!' || ch == '<' || ch == '>') {
       if (strchr("sSiIlLqQ", (int)t) == NULL) {
-        char ch_str = (char)ch;
-        mrb_raisef(mrb, E_ARGUMENT_ERROR, "'%S' allowed only after types sSiIlLqQ", mrb_str_new(mrb, &ch_str, 1));
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "'%c' allowed only after types sSiIlLqQ", ch);
       }
       if (ch == '_' || ch == '!') {
         flags |= PACK_FLAG_s;
@@ -1156,7 +1155,7 @@ mrb_pack_pack(mrb_state *mrb, mrb_value ary)
 #endif
       else if (type == PACK_TYPE_STRING) {
         if (!mrb_string_p(o)) {
-          mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %S into String", mrb_class_path(mrb, mrb_obj_class(mrb, o)));
+          mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %T into String", o);
         }
       }
 
diff --git a/mrbgems/mruby-socket/src/socket.c b/mrbgems/mruby-socket/src/socket.c
index 9b06274dc..eaca27779 100644
--- a/mrbgems/mruby-socket/src/socket.c
+++ b/mrbgems/mruby-socket/src/socket.c
@@ -171,7 +171,7 @@ mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
 
   error = getaddrinfo(hostname, servname, &hints, &res0);
   if (error) {
-    mrb_raisef(mrb, E_SOCKET_ERROR, "getaddrinfo: %S", mrb_str_new_cstr(mrb, gai_strerror(error)));
+    mrb_raisef(mrb, E_SOCKET_ERROR, "getaddrinfo: %s", gai_strerror(error));
   }
   mrb_cv_set(mrb, klass, mrb_intern_lit(mrb, "_lastai"), mrb_cptr_value(mrb, res0));
 
@@ -206,7 +206,7 @@ mrb_addrinfo_getnameinfo(mrb_state *mrb, mrb_value self)
   }
   error = getnameinfo((struct sockaddr *)RSTRING_PTR(sastr), (socklen_t)RSTRING_LEN(sastr), RSTRING_PTR(host), NI_MAXHOST, RSTRING_PTR(serv), NI_MAXSERV, (int)flags);
   if (error) {
-    mrb_raisef(mrb, E_SOCKET_ERROR, "getnameinfo: %S", mrb_str_new_cstr(mrb, gai_strerror(error)));
+    mrb_raisef(mrb, E_SOCKET_ERROR, "getnameinfo: %s", gai_strerror(error));
   }
   ary = mrb_ary_new_capa(mrb, 2);
   mrb_str_resize(mrb, host, strlen(RSTRING_PTR(host)));
@@ -476,7 +476,7 @@ mrb_basicsocket_setsockopt(mrb_state *mrb, mrb_value self)
     optname = mrb_fixnum(mrb_funcall(mrb, so, "optname", 0));
     optval = mrb_funcall(mrb, so, "data", 0);
   } else {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%S for 3)", mrb_fixnum_value(argc));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "wrong number of arguments (%i for 3)", argc);
   }
 
   s = socket_fd(mrb, self);
@@ -702,7 +702,7 @@ mrb_socket_sockaddr_un(mrb_state *mrb, mrb_value klass)
 
   mrb_get_args(mrb, "S", &path);
   if ((size_t)RSTRING_LEN(path) > sizeof(sunp->sun_path) - 1) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "too long unix socket path (max: %S bytes)", mrb_fixnum_value(sizeof(sunp->sun_path) - 1));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "too long unix socket path (max: %d bytes)", (int)sizeof(sunp->sun_path) - 1);
   }
   s = mrb_str_buf_new(mrb, sizeof(struct sockaddr_un));
   sunp = (struct sockaddr_un *)RSTRING_PTR(s);
diff --git a/mrbgems/mruby-sprintf/src/sprintf.c b/mrbgems/mruby-sprintf/src/sprintf.c
index 985ffe276..c8d51962e 100644
--- a/mrbgems/mruby-sprintf/src/sprintf.c
+++ b/mrbgems/mruby-sprintf/src/sprintf.c
@@ -81,7 +81,7 @@ mrb_fix2binstr(mrb_state *mrb, mrb_value x, int base)
   char d;
 
   if (base != 2) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "invalid radix %S", mrb_fixnum_value(base));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "invalid radix %d", base);
   }
   if (val == 0) {
     return mrb_str_new_lit(mrb, "0");
@@ -144,10 +144,10 @@ check_next_arg(mrb_state *mrb, int posarg, int nextarg)
 {
   switch (posarg) {
   case -1:
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unnumbered(%S) mixed with numbered", mrb_fixnum_value(nextarg));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unnumbered(%d) mixed with numbered", nextarg);
     break;
   case -2:
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unnumbered(%S) mixed with named", mrb_fixnum_value(nextarg));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unnumbered(%d) mixed with named", nextarg);
     break;
   default:
     break;
@@ -158,26 +158,26 @@ static void
 check_pos_arg(mrb_state *mrb, mrb_int posarg, mrb_int n)
 {
   if (posarg > 0) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "numbered(%S) after unnumbered(%S)",
-               mrb_fixnum_value(n), mrb_fixnum_value(posarg));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "numbered(%i) after unnumbered(%i)",
+               n, posarg);
   }
   if (posarg == -2) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "numbered(%S) after named", mrb_fixnum_value(n));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "numbered(%i) after named", n);
   }
   if (n < 1) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "invalid index - %S$", mrb_fixnum_value(n));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "invalid index - %i$", n);
   }
 }
 
 static void
-check_name_arg(mrb_state *mrb, int posarg, const char *name, mrb_int len)
+check_name_arg(mrb_state *mrb, int posarg, const char *name, size_t len)
 {
   if (posarg > 0) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "named%S after unnumbered(%S)",
-               mrb_str_new(mrb, (name), (len)), mrb_fixnum_value(posarg));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "named%l after unnumbered(%d)",
+               name, len, posarg);
   }
   if (posarg == -1) {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "named%S after numbered", mrb_str_new(mrb, (name), (len)));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "named%l after numbered", name, len);
   }
 }
 
@@ -580,7 +580,7 @@ mrb_str_format(mrb_state *mrb, mrb_int argc, const mrb_value *argv, mrb_value fm
 retry:
     switch (*p) {
       default:
-        mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed format string - \\%%S", mrb_str_new(mrb, p, 1));
+        mrb_raisef(mrb, E_ARGUMENT_ERROR, "malformed format string - %%%c", *p);
         break;
 
       case ' ':
@@ -619,7 +619,7 @@ retry:
         GETNUM(n, width);
         if (*p == '$') {
           if (!mrb_undef_p(nextvalue)) {
-            mrb_raisef(mrb, E_ARGUMENT_ERROR, "value given twice - %S$", mrb_fixnum_value(n));
+            mrb_raisef(mrb, E_ARGUMENT_ERROR, "value given twice - %i$", n);
           }
           nextvalue = GETPOSARG(n);
           p++;
@@ -639,14 +639,14 @@ retry:
         for (; p < end && *p != term; )
           p++;
         if (id) {
-          mrb_raisef(mrb, E_ARGUMENT_ERROR, "name%S after <%S>",
-                     mrb_str_new(mrb, start, p - start + 1), mrb_sym2str(mrb, id));
+          mrb_raisef(mrb, E_ARGUMENT_ERROR, "name%l after <%n>",
+                     start, p - start + 1, id);
         }
         symname = mrb_str_new(mrb, start + 1, p - start - 1);
         id = mrb_intern_str(mrb, symname);
-        nextvalue = GETNAMEARG(mrb_symbol_value(id), start, (mrb_int)(p - start + 1));
+        nextvalue = GETNAMEARG(mrb_symbol_value(id), start, p - start + 1);
         if (mrb_undef_p(nextvalue)) {
-          mrb_raisef(mrb, E_KEY_ERROR, "key%S not found", mrb_str_new(mrb, start, p - start + 1));
+          mrb_raisef(mrb, E_KEY_ERROR, "key%l not found", start, p - start + 1);
         }
         if (term == '}') goto format_s;
         p++;
@@ -1089,7 +1089,7 @@ retry:
   if (posarg >= 0 && nextarg < argc) {
     const char *mesg = "too many arguments for format string";
     if (mrb_test(ruby_debug)) mrb_raise(mrb, E_ARGUMENT_ERROR, mesg);
-    if (mrb_test(ruby_verbose)) mrb_warn(mrb, "%S", mrb_str_new_cstr(mrb, mesg));
+    if (mrb_test(ruby_verbose)) mrb_warn(mrb, "%s", mesg);
   }
 #endif
   mrb_str_resize(mrb, result, blen);
diff --git a/mrbgems/mruby-string-ext/src/string.c b/mrbgems/mruby-string-ext/src/string.c
index 80b277444..a946140dd 100644
--- a/mrbgems/mruby-string-ext/src/string.c
+++ b/mrbgems/mruby-string-ext/src/string.c
@@ -40,7 +40,7 @@ int_chr_binary(mrb_state *mrb, mrb_value num)
   mrb_value str;
 
   if (cp < 0 || 0xff < cp) {
-    mrb_raisef(mrb, E_RANGE_ERROR, "%S out of char range", num);
+    mrb_raisef(mrb, E_RANGE_ERROR, "%v out of char range", num);
   }
   c = (char)cp;
   str = mrb_str_new(mrb, &c, 1);
@@ -59,7 +59,7 @@ int_chr_utf8(mrb_state *mrb, mrb_value num)
   uint32_t ascii_flag = 0;
 
   if (cp < 0 || 0x10FFFF < cp) {
-    mrb_raisef(mrb, E_RANGE_ERROR, "%S out of char range", num);
+    mrb_raisef(mrb, E_RANGE_ERROR, "%v out of char range", num);
   }
   if (cp < 0x80) {
     utf8[0] = (char)cp;
@@ -114,7 +114,7 @@ mrb_str_setbyte(mrb_state *mrb, mrb_value str)
 
   len = RSTRING_LEN(str);
   if (pos < -len || len <= pos)
-    mrb_raisef(mrb, E_INDEX_ERROR, "index %S out of string", mrb_fixnum_value(pos));
+    mrb_raisef(mrb, E_INDEX_ERROR, "index %i out of string", pos);
   if (pos < 0)
     pos += len;
 
@@ -583,8 +583,7 @@ str_tr(mrb_state *mrb, mrb_value str, mrb_value p1, mrb_value p2, mrb_bool squee
           continue;
         }
         if (c > 0x80) {
-          mrb_raisef(mrb, E_ARGUMENT_ERROR, "character (%S) out of range",
-                     mrb_fixnum_value((mrb_int)c));
+          mrb_raisef(mrb, E_ARGUMENT_ERROR, "character (%i) out of range", c);
         }
 	lastch = c;
 	s[i] = (char)c;
@@ -956,7 +955,7 @@ mrb_int_chr(mrb_state *mrb, mrb_value num)
   }
 #endif
   else {
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unknown encoding name - %S", enc);
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "unknown encoding name - %v", enc);
   }
   /* not reached */
   return mrb_nil_value();
diff --git a/mrbgems/mruby-struct/src/struct.c b/mrbgems/mruby-struct/src/struct.c
index e04fe13ad..ebe711ed3 100644
--- a/mrbgems/mruby-struct/src/struct.c
+++ b/mrbgems/mruby-struct/src/struct.c
@@ -66,8 +66,8 @@ struct_members(mrb_state *mrb, mrb_value s)
     }
     else {
       mrb_raisef(mrb, E_TYPE_ERROR,
-                 "struct size differs (%S required %S given)",
-                 mrb_fixnum_value(RARRAY_LEN(members)), mrb_fixnum_value(RSTRUCT_LEN(s)));
+                 "struct size differs (%i required %i given)",
+                 RARRAY_LEN(members), RSTRUCT_LEN(s));
     }
   }
   return members;
@@ -205,10 +205,10 @@ make_struct(mrb_state *mrb, mrb_value name, mrb_value members, struct RClass *kl
     mrb_to_str(mrb, name);
     id = mrb_obj_to_sym(mrb, name);
     if (!mrb_const_name_p(mrb, RSTRING_PTR(name), RSTRING_LEN(name))) {
-      mrb_name_error(mrb, id, "identifier %S needs to be constant", name);
+      mrb_name_error(mrb, id, "identifier %v needs to be constant", name);
     }
     if (mrb_const_defined_at(mrb, mrb_obj_value(klass), id)) {
-      mrb_warn(mrb, "redefining constant Struct::%S", name);
+      mrb_warn(mrb, "redefining constant Struct::%v", name);
       mrb_const_remove(mrb, mrb_obj_value(klass), id);
     }
     c = mrb_define_class_under(mrb, klass, RSTRING_PTR(name), klass);
@@ -388,7 +388,7 @@ struct_aref_sym(mrb_state *mrb, mrb_value obj, mrb_sym id)
       return ptr[i];
     }
   }
-  mrb_name_error(mrb, id, "no member '%S' in struct", mrb_sym2str(mrb, id));
+  mrb_name_error(mrb, id, "no member '%n' in struct", id);
   return mrb_nil_value();       /* not reached */
 }
 
@@ -399,12 +399,10 @@ struct_aref_int(mrb_state *mrb, mrb_value s, mrb_int i)
 
   if (idx < 0)
     mrb_raisef(mrb, E_INDEX_ERROR,
-               "offset %S too small for struct(size:%S)",
-               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+               "offset %i too small for struct(size:%i)", i, RSTRUCT_LEN(s));
   if (RSTRUCT_LEN(s) <= idx)
     mrb_raisef(mrb, E_INDEX_ERROR,
-               "offset %S too large for struct(size:%S)",
-               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+               "offset %i too large for struct(size:%i)", i, RSTRUCT_LEN(s));
   return RSTRUCT_PTR(s)[idx];
 }
 
@@ -437,7 +435,7 @@ mrb_struct_aref(mrb_state *mrb, mrb_value s)
     mrb_value sym = mrb_check_intern_str(mrb, idx);
 
     if (mrb_nil_p(sym)) {
-      mrb_name_error(mrb, mrb_intern_str(mrb, idx), "no member '%S' in struct", idx);
+      mrb_name_error(mrb, mrb_intern_str(mrb, idx), "no member '%v' in struct", idx);
     }
     idx = sym;
   }
@@ -465,7 +463,7 @@ mrb_struct_aset_sym(mrb_state *mrb, mrb_value s, mrb_sym id, mrb_value val)
       return val;
     }
   }
-  mrb_name_error(mrb, id, "no member '%S' in struct", mrb_sym2str(mrb, id));
+  mrb_name_error(mrb, id, "no member '%n' in struct", id);
   return val;                   /* not reach */
 }
 
@@ -504,7 +502,7 @@ mrb_struct_aset(mrb_state *mrb, mrb_value s)
     mrb_value sym = mrb_check_intern_str(mrb, idx);
 
     if (mrb_nil_p(sym)) {
-      mrb_name_error(mrb, mrb_intern_str(mrb, idx), "no member '%S' in struct", idx);
+      mrb_name_error(mrb, mrb_intern_str(mrb, idx), "no member '%v' in struct", idx);
     }
     idx = sym;
   }
@@ -516,13 +514,11 @@ mrb_struct_aset(mrb_state *mrb, mrb_value s)
   if (i < 0) i = RSTRUCT_LEN(s) + i;
   if (i < 0) {
     mrb_raisef(mrb, E_INDEX_ERROR,
-               "offset %S too small for struct(size:%S)",
-               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+               "offset %i too small for struct(size:%i)", i, RSTRUCT_LEN(s));
   }
   if (RSTRUCT_LEN(s) <= i) {
     mrb_raisef(mrb, E_INDEX_ERROR,
-               "offset %S too large for struct(size:%S)",
-               mrb_fixnum_value(i), mrb_fixnum_value(RSTRUCT_LEN(s)));
+               "offset %i too large for struct(size:%i)", i, RSTRUCT_LEN(s));
   }
   mrb_struct_modify(mrb, s);
   return RSTRUCT_PTR(s)[i] = val;
diff --git a/mrbgems/mruby-time/src/time.c b/mrbgems/mruby-time/src/time.c
index 16461095c..9b0549bea 100644
--- a/mrbgems/mruby-time/src/time.c
+++ b/mrbgems/mruby-time/src/time.c
@@ -267,7 +267,7 @@ mrb_to_time_t(mrb_state *mrb, mrb_value obj, time_t *usec)
   return t;
 
 out_of_range:
-  mrb_raisef(mrb, E_ARGUMENT_ERROR, "%S out of Time range", obj);
+  mrb_raisef(mrb, E_ARGUMENT_ERROR, "%v out of Time range", obj);
 
   /* not reached */
   if (usec) { *usec = 0; }
@@ -293,7 +293,7 @@ time_update_datetime(mrb_state *mrb, struct mrb_time *self, int dealloc)
     mrb_sec sec = (mrb_sec)t;
 
     if (dealloc) mrb_free(mrb, self);
-    mrb_raisef(mrb, E_ARGUMENT_ERROR, "%S out of Time range", mrb_sec_value(mrb, sec));
+    mrb_raisef(mrb, E_ARGUMENT_ERROR, "%v out of Time range", mrb_sec_value(mrb, sec));
     /* not reached */
     return NULL;
   }