Suppress self-assignment warning.

Cython/Compiler/Nodes.py

@@ -4089,8 +4089,7 @@ class GeneratorBodyDefNode(DefNode):
                 lenv.scope_class.type.cast_code('%s->closure' %
                                                 Naming.generator_cname)))
             # FIXME: this silences a potential "unused" warning => try to avoid unused closures in more cases
-            code.putln("if (1); else %s = %s;" % (
-                Naming.cur_scope_cname, Naming.cur_scope_cname))
+            code.putln("CYTHON_MAYBE_UNUSED_VAR(%s);" % Naming.cur_scope_cname)
 
         code.mark_pos(self.pos)
         code.putln("")

Cython/Utility/ModuleSetupCode.c

@@ -399,6 +399,14 @@
 # endif
 #endif
 
+#ifndef CYTHON_MAYBE_UNUSED_VAR
+#  if defined(__cplusplus)
+     template<class T> void CYTHON_MAYBE_UNUSED_VAR( const T& ) { }
+#  else
+#    define CYTHON_MAYBE_UNUSED_VAR(x) (void)(x)
+#  endif
+#endif
+
 #ifndef CYTHON_NCP_UNUSED
 # if CYTHON_COMPILING_IN_CPYTHON
 #  define CYTHON_NCP_UNUSED