clean up and simplify code generation code for fused types

Cython/Compiler/FusedNode.py

@@ -260,22 +260,17 @@ class FusedCFuncDefNode(StatListNode):
         Genereate Cython code for instance checks, matching an object to
         specialized types.
         """
-        if_ = 'if'
         for specialized_type in normal_types:
             # all_numeric = all_numeric and specialized_type.is_numeric
-            py_type_name = specialized_type.py_type_name()
-            specialized_type_name = specialized_type.specialization_string
-            pyx_code.context.update(locals())
+            pyx_code.context.update(
+                py_type_name=specialized_type.py_type_name(),
+                specialized_type_name=specialized_type.specialization_string,
+            )
             pyx_code.put_chunk(
                 u"""
-                    {{if_}} isinstance(arg, {{py_type_name}}):
+                    elif isinstance(arg, {{py_type_name}}):
                         dest_sig[{{dest_sig_idx}}] = '{{specialized_type_name}}'
                 """)
-            if_ = 'elif'
-
-        if not normal_types:
-            # we need an 'if' to match the following 'else'
-            pyx_code.putln("if 0: pass")
 
     def _dtype_name(self, dtype):
         if dtype.is_typedef:
@@ -398,8 +393,6 @@ class FusedCFuncDefNode(StatListNode):
         to each specialization, which obtains the buffer each time and tries
         to match the format string.
         """
-        if buffer_types:
-            if pyx_code.indenter(u"else:"):
         # The first thing to find a match in this loop breaks out of the loop
         if pyx_code.indenter(u"while 1:"):
             pyx_code.put_chunk(
@@ -435,10 +428,6 @@ class FusedCFuncDefNode(StatListNode):
             pyx_code.putln("break")
             pyx_code.dedent()
 
-                pyx_code.dedent()
-        else:
-            pyx_code.putln("else: %s" % self.no_match)
-
     def _buffer_declarations(self, pyx_code, decl_code, all_buffer_types):
         """
         If we have any buffer specializations, write out some variable
@@ -569,7 +558,7 @@ class FusedCFuncDefNode(StatListNode):
                     # FIXME: use a typed signature - currently fails badly because
                     #        default arguments inherit the types we specify here!
 
-                    dest_sig = [{{for _ in range(n_fused)}}None,{{endfor}}]
+                    dest_sig = [None] * {{n_fused}}
 
                     if kwargs is None:
                         kwargs = {}
@@ -606,10 +595,19 @@ class FusedCFuncDefNode(StatListNode):
 
                 normal_types, buffer_types = self._split_fused_types(arg)
                 self._unpack_argument(pyx_code)
+
+                # we need an 'if' to allow the following elif/else branches
+                pyx_code.putln("if 0: pass")
+                if normal_types:
                     self._fused_instance_checks(normal_types, pyx_code, env)
+                if pyx_code.indenter("else:"):
+                    if buffer_types:
                         self._buffer_checks(buffer_types, pyx_code, decl_code, env)
-                fused_index += 1
+                    else:
+                        pyx_code.putln(self.no_match)
+                    pyx_code.dedent()
 
+                fused_index += 1
                 all_buffer_types.update(buffer_types)
 
             if arg.default:
@@ -646,7 +644,9 @@ class FusedCFuncDefNode(StatListNode):
         fragment_code = pyx_code.getvalue()
         # print decl_code.getvalue()
         # print fragment_code
-        fragment = TreeFragment.TreeFragment(fragment_code, level='module')
+        from .Optimize import ConstantFolding
+        fragment = TreeFragment.TreeFragment(
+            fragment_code, level='module', pipeline=[ConstantFolding()])
         ast = TreeFragment.SetPosTransform(self.node.pos)(fragment.root)
         UtilityCode.declare_declarations_in_scope(
             decl_code.getvalue(), env.global_scope())