Fix Issues reported by PVS-Studio static analyzer

* vm.c (vm_set_main_stack): remove unnecessary check.  toplevel
  binding must be initialized.  [Bug #12611] (N1)
* win32/win32.c (w32_symlink): fix return type.  [Bug #12611] (N3)
* string.c (rb_str_split_m): simplify the condition.
  [Bug #12611](N4)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55729 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,13 @@
+Fri Jul 22 19:55:20 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm.c (vm_set_main_stack): remove unnecessary check.  toplevel
+	  binding must be initialized.  [Bug #12611] (N1)
+
+	* win32/win32.c (w32_symlink): fix return type.  [Bug #12611] (N3)
+
+	* string.c (rb_str_split_m): simplify the condition.
+	  [Bug #12611](N4)
+
 Fri Jul 22 17:13:37 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>
 
 	* string.c (String#dump): Change escaping of non-ASCII characters in

string.c

@@ -7235,7 +7235,7 @@ rb_str_split_m(int argc, VALUE *argv, VALUE str)
 		    beg = start;
 		}
 		else {
-                    if (ptr+start == ptr+len)
+                    if (start == len)
                         start++;
                     else
                         start += rb_enc_fast_mbclen(ptr+start,ptr+len,enc);

vm.c

@@ -379,7 +379,7 @@ vm_set_main_stack(rb_thread_t *th, const rb_iseq_t *iseq)
     vm_set_eval_stack(th, iseq, 0, &env->block);
 
     /* save binding */
-    if (bind && iseq->body->local_size > 0) {
+    if (iseq->body->local_size > 0) {
 	bind->env = vm_make_env_object(th, th->cfp);
     }
 }

win32/win32.c

@@ -4947,7 +4947,7 @@ w32_symlink(UINT cp, const char *src, const char *link)
     DWORD flag = 0;
     BOOLEAN ret;
 
-    typedef DWORD (WINAPI *create_symbolic_link_func)(WCHAR*, WCHAR*, DWORD);
+    typedef BOOLEAN (WINAPI *create_symbolic_link_func)(WCHAR*, WCHAR*, DWORD);
     static create_symbolic_link_func create_symbolic_link =
 	(create_symbolic_link_func)-1;