Make raising a KeyError not the default for parsing names.

Cython/Compiler/Parsing.py

@@ -532,12 +532,8 @@ def p_atom(s):
 
 def p_name(s, name):
     pos = s.position()
-    if not s.compile_time_expr:
-        try:
+    if not s.compile_time_expr and name in s.compile_time_env:
         value = s.compile_time_env.lookup_here(name)
-        except KeyError:
-            pass
-        else:
         rep = repr(value)
         if isinstance(value, bool):
             return ExprNodes.BoolNode(pos, value = value)

Cython/Compiler/Scanning.pxd

 from Cython.Plex.Scanners cimport Scanner
 
+cdef class CompileTimeScope:
+    cdef public entries
+    cdef public outer
+
 cdef class PyrexScanner(Scanner):
     cdef public context
     cdef public list included_files

Cython/Compiler/Scanning.py

@@ -176,7 +176,7 @@ resword_dict = build_resword_dict()
 
 #------------------------------------------------------------------
 
-class CompileTimeScope(object):
+class CompileTimeScope:
 
     def __init__(self, outer = None):
         self.entries = {}
@@ -188,6 +188,9 @@ class CompileTimeScope(object):
     def lookup_here(self, name):
         return self.entries[name]
         
+    def __contains__(self, name):
+        return name in self.entries
+    
     def lookup(self, name):
         try:
             return self.lookup_here(name)