X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fex.h;h=de0fbff6aa8a9da2c68a79f4dfa625569bcfde78;hp=f0e6db51f150b302393882064f7411222ff277cc;hb=0e22c5a63bb0f5792beba531d77944db18e3c191;hpb=67edef78ce992a8f6ad704bfac228b8dec6eacd2

diff --git a/ginac/ex.h b/ginac/ex.h
index f0e6db51..de0fbff6 100644
--- a/ginac/ex.h
+++ b/ginac/ex.h
@@ -3,7 +3,7 @@
  *  Interface to GiNaC's light-weight expression handles. */
 
 /*
- *  GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2015 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -32,6 +32,11 @@
 #include <stack>
 
 namespace GiNaC {
+#ifdef _MSC_VER
+  // MSVC produces a different symbol for _ex0 when it is declared inside   
+  // ex::is_zero() than when it is declared at top level as follows
+  extern const ex _ex0;
+#endif
 
 /** Helper class to initialize the library.  There must be one static object
  *  of this class in every object file that makes use of our flyweights in
@@ -204,7 +209,12 @@ public:
 	// comparison
 	int compare(const ex & other) const;
 	bool is_equal(const ex & other) const;
-	bool is_zero() const { extern const ex _ex0; return is_equal(_ex0); }
+	bool is_zero() const { 
+#ifndef _MSC_VER
+	  extern const ex _ex0;
+#endif
+	  return is_equal(_ex0); 
+	}
 	bool is_zero_matrix() const;
 	
 	// symmetry