Fix up call convention determination for win32

ext/ffi_c/FunctionInfo.c

@@ -2,27 +2,19 @@
  * Copyright (c) 2009, Wayne Meissner
  * All rights reserved.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
+ * This file is part of ruby-ffi.
  *
- * * Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright notice
- *   this list of conditions and the following disclaimer in the documentation
- *   and/or other materials provided with the distribution.
- * * The name of the author or authors may not be used to endorse or promote
- *   products derived from this software without specific prior written permission.
+ * This code is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License version 3 only, as
+ * published by the Free Software Foundation.
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+ * version 3 for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * version 3 along with this work.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <sys/param.h>
@@ -98,6 +90,9 @@ fntype_initialize(int argc, VALUE* argv, VALUE self)
     ffi_status status;
     VALUE rbReturnType = Qnil, rbParamTypes = Qnil, rbOptions = Qnil;
     VALUE rbEnums = Qnil, rbConvention = Qnil, rbBlocking = Qnil;
+#if defined(_WIN32) || defined(__WIN32__)
+    VALUE rbConventionStr;
+#endif
     int i, nargs;
 
     nargs = rb_scan_args(argc, argv, "21", &rbReturnType, &rbParamTypes, &rbOptions);
@@ -158,8 +153,8 @@ fntype_initialize(int argc, VALUE* argv, VALUE self)
 
 
 #if defined(_WIN32) || defined(__WIN32__)
-    VALUE rbConventionStr = rb_funcall2(rbConvention, rb_intern("to_s"), 0, NULL);
-    fnInfo->abi = (rbConvention != Qnil && strcmp(StringValueCStr(rbConventionStr), "stdcall") == 0)
+    rbConventionStr = (rbConvention != Qnil) ? rb_funcall2(rbConvention, rb_intern("to_s"), 0, NULL) : Qnil;
+    fnInfo->abi = (rbConventionStr != Qnil && strcmp(StringValueCStr(rbConventionStr), "stdcall") == 0)
             ? FFI_STDCALL : FFI_DEFAULT_ABI;
 #else
     fnInfo->abi = FFI_DEFAULT_ABI;