Symtab.py

#
#   Symbol Table
#

from __future__ import absolute_import

import re
import copy
import operator

try:
    import __builtin__ as builtins
except ImportError:  # Py3
    import builtins

from ..Utils import try_finally_contextmanager
from .Errors import warning, error, InternalError
from .StringEncoding import EncodedString
from . import Options, Naming
from . import PyrexTypes
from .PyrexTypes import py_object_type, unspecified_type
from .TypeSlots import (
    pyfunction_signature, pymethod_signature, richcmp_special_methods,
    get_slot_table, get_property_accessor_signature)
from . import Future

from . import Code

iso_c99_keywords = {
    'auto', 'break', 'case', 'char', 'const', 'continue', 'default', 'do',
    'double', 'else', 'enum', 'extern', 'float', 'for', 'goto', 'if',
    'int', 'long', 'register', 'return', 'short', 'signed', 'sizeof',
    'static', 'struct', 'switch', 'typedef', 'union', 'unsigned', 'void',
    'volatile', 'while',
    '_Bool', '_Complex'', _Imaginary', 'inline', 'restrict',
}


def c_safe_identifier(cname):
    # There are some C limitations on struct entry names.
    if ((cname[:2] == '__' and not (cname.startswith(Naming.pyrex_prefix)
                                    or cname in ('__weakref__', '__dict__')))
            or cname in iso_c99_keywords):
        cname = Naming.pyrex_prefix + cname
    return cname

def punycodify_name(cname, mangle_with=None):
    # if passed the mangle_with should be a byte string
    # modified from  PEP489
    try:
        cname.encode('ascii')
    except UnicodeEncodeError:
        cname = cname.encode('punycode').replace(b'-', b'_').decode('ascii')
        if mangle_with:
            # sometimes it necessary to mangle unicode names alone where
            # they'll be inserted directly into C, because the punycode
            # transformation can turn them into invalid identifiers
            cname = "%s_%s" % (mangle_with, cname)
        elif cname.startswith(Naming.pyrex_prefix):
            # a punycode name could also be a valid ascii variable name so
            # change the prefix to distinguish
            cname = cname.replace(Naming.pyrex_prefix,
                                  Naming.pyunicode_identifier_prefix, 1)

    return cname




class BufferAux(object):
    writable_needed = False

    def __init__(self, buflocal_nd_var, rcbuf_var):
        self.buflocal_nd_var = buflocal_nd_var
        self.rcbuf_var = rcbuf_var

    def __repr__(self):
        return "<BufferAux %r>" % self.__dict__


class Entry(object):
    # A symbol table entry in a Scope or ModuleNamespace.
    #
    # name             string     Python name of entity
    # cname            string     C name of entity
    # type             PyrexType  Type of entity
    # doc              string     Doc string
    # annotation       ExprNode   PEP 484/526 annotation
    # init             string     Initial value
    # visibility       'private' or 'public' or 'extern'
    # is_builtin       boolean    Is an entry in the Python builtins dict
    # is_cglobal       boolean    Is a C global variable
    # is_pyglobal      boolean    Is a Python module-level variable
    #                               or class attribute during
    #                               class construction
    # is_member        boolean    Is an assigned class member
    # is_pyclass_attr  boolean    Is a name in a Python class namespace
    # is_variable      boolean    Is a variable
    # is_cfunction     boolean    Is a C function
    # is_cmethod       boolean    Is a C method of an extension type
    # is_builtin_cmethod boolean  Is a C method of a builtin type (implies is_cmethod)
    # is_unbound_cmethod boolean  Is an unbound C method of an extension type
    # is_final_cmethod   boolean  Is non-overridable C method
    # is_inline_cmethod  boolean  Is inlined C method
    # is_anonymous     boolean    Is a anonymous pyfunction entry
    # is_type          boolean    Is a type definition
    # is_cclass        boolean    Is an extension class
    # is_cpp_class     boolean    Is a C++ class
    # is_const         boolean    Is a constant
    # is_property      boolean    Is a property of an extension type:
    # doc_cname        string or None  C const holding the docstring
    # getter_cname     string          C func for getting property
    # setter_cname     string          C func for setting or deleting property
    # is_cproperty     boolean         Is an inline property of an external type
    # is_self_arg      boolean    Is the "self" arg of an exttype method
    # is_arg           boolean    Is the arg of a method
    # is_local         boolean    Is a local variable
    # in_closure       boolean    Is referenced in an inner scope
    # in_subscope      boolean    Belongs to a generator expression scope
    # is_readonly      boolean    Can't be assigned to
    # func_cname       string     C func implementing Python func
    # func_modifiers   [string]   C function modifiers ('inline')
    # pos              position   Source position where declared
    # namespace_cname  string     If is_pyglobal, the C variable
    #                               holding its home namespace
    # pymethdef_cname  string     PyMethodDef structure
    # signature        Signature  Arg & return types for Python func
    # as_variable      Entry      Alternative interpretation of extension
    #                               type name or builtin C function as a variable
    # xdecref_cleanup  boolean    Use Py_XDECREF for error cleanup
    # in_cinclude      boolean    Suppress C declaration code
    # enum_values      [Entry]    For enum types, list of values
    # qualified_name   string     "modname.funcname" or "modname.classname"
    #                               or "modname.classname.funcname"
    # is_declared_generic  boolean  Is declared as PyObject * even though its
    #                                 type is an extension type
    # as_module        None       Module scope, if a cimported module
    # is_inherited     boolean    Is an inherited attribute of an extension type
    # pystring_cname   string     C name of Python version of string literal
    # is_interned      boolean    For string const entries, value is interned
    # is_identifier    boolean    For string const entries, value is an identifier
    # used             boolean
    # is_special       boolean    Is a special method or property accessor
    #                               of an extension type
    # defined_in_pxd   boolean    Is defined in a .pxd file (not just declared)
    # api              boolean    Generate C API for C class or function
    # utility_code     string     Utility code needed when this entry is used
    #
    # buffer_aux       BufferAux or None  Extra information needed for buffer variables
    # inline_func_in_pxd boolean  Hacky special case for inline function in pxd file.
    #                             Ideally this should not be necessary.
    # might_overflow   boolean    In an arithmetic expression that could cause
    #                             overflow (used for type inference).
    # utility_code_definition     For some Cython builtins, the utility code
    #                             which contains the definition of the entry.
    #                             Currently only supported for CythonScope entries.
    # error_on_uninitialized      Have Control Flow issue an error when this entry is
    #                             used uninitialized
    # cf_used          boolean    Entry is used
    # is_fused_specialized boolean Whether this entry of a cdef or def function
    #                              is a specialization
    # is_cgetter       boolean    Is a c-level getter function
    # is_cpp_optional  boolean    Entry should be declared as std::optional (cpp_locals directive)
    # known_standard_library_import     Either None (default), an empty string (definitely can't be determined)
    #                             or a string of "modulename.something.attribute"
    #                             Used for identifying imports from typing/dataclasses etc
    # pytyping_modifiers          Python type modifiers like "typing.ClassVar" but also "dataclasses.InitVar"
    # enum_int_value  None or int  If known, the int that corresponds to this enum value

    # TODO: utility_code and utility_code_definition serves the same purpose...

    inline_func_in_pxd = False
    borrowed = 0
    init = ""
    annotation = None
    pep563_annotation = None
    visibility = 'private'
    is_builtin = 0
    is_cglobal = 0
    is_pyglobal = 0
    is_member = 0
    is_pyclass_attr = 0
    is_variable = 0
    is_cfunction = 0
    is_cmethod = 0
    is_builtin_cmethod = False
    is_unbound_cmethod = 0
    is_final_cmethod = 0
    is_inline_cmethod = 0
    is_anonymous = 0
    is_type = 0
    is_cclass = 0
    is_cpp_class = 0
    is_const = 0
    is_property = 0
    is_cproperty = 0
    doc_cname = None
    getter_cname = None
    setter_cname = None
    is_self_arg = 0
    is_arg = 0
    is_local = 0
    in_closure = 0
    from_closure = 0
    in_subscope = 0
    is_declared_generic = 0
    is_readonly = 0
    pyfunc_cname = None
    func_cname = None
    func_modifiers = []
    final_func_cname = None
    doc = None
    as_variable = None
    xdecref_cleanup = 0
    in_cinclude = 0
    as_module = None
    is_inherited = 0
    pystring_cname = None
    is_identifier = 0
    is_interned = 0
    used = 0
    is_special = 0
    defined_in_pxd = 0
    is_implemented = 0
    api = 0
    utility_code = None
    is_overridable = 0
    buffer_aux = None
    prev_entry = None
    might_overflow = 0
    fused_cfunction = None
    is_fused_specialized = False
    utility_code_definition = None
    needs_property = False
    in_with_gil_block = 0
    from_cython_utility_code = None
    error_on_uninitialized = False
    cf_used = True
    outer_entry = None
    is_cgetter = False
    is_cpp_optional = False
    known_standard_library_import = None
    pytyping_modifiers = None
    enum_int_value = None

    def __init__(self, name, cname, type, pos = None, init = None):
        self.name = name
        self.cname = cname
        self.type = type
        self.pos = pos
        self.init = init
        self.overloaded_alternatives = []
        self.cf_assignments = []
        self.cf_references = []
        self.inner_entries = []
        self.defining_entry = self

    def __repr__(self):
        return "%s(<%x>, name=%s, type=%s)" % (type(self).__name__, id(self), self.name, self.type)

    def already_declared_here(self):
        error(self.pos, "Previous declaration is here")

    def redeclared(self, pos):
        error(pos, "'%s' does not match previous declaration" % self.name)
        self.already_declared_here()

    def all_alternatives(self):
        return [self] + self.overloaded_alternatives

    def all_entries(self):
        return [self] + self.inner_entries

    def __lt__(left, right):
        if isinstance(left, Entry) and isinstance(right, Entry):
            return (left.name, left.cname) < (right.name, right.cname)
        else:
            return NotImplemented

    @property
    def cf_is_reassigned(self):
        return len(self.cf_assignments) > 1

    def make_cpp_optional(self):
        assert self.type.is_cpp_class
        self.is_cpp_optional = True
        assert not self.utility_code  # we're not overwriting anything?
        self.utility_code_definition = Code.UtilityCode.load_cached("OptionalLocals", "CppSupport.cpp")

    def declared_with_pytyping_modifier(self, modifier_name):
        return modifier_name in self.pytyping_modifiers if self.pytyping_modifiers else False


class InnerEntry(Entry):
    """
    An entry in a closure scope that represents the real outer Entry.
    """
    from_closure = True

    def __init__(self, outer_entry, scope):
        Entry.__init__(self, outer_entry.name,
                       outer_entry.cname,
                       outer_entry.type,
                       outer_entry.pos)
        self.outer_entry = outer_entry
        self.scope = scope

        # share state with (outermost) defining entry
        outermost_entry = outer_entry
        while outermost_entry.outer_entry:
            outermost_entry = outermost_entry.outer_entry
        self.defining_entry = outermost_entry
        self.inner_entries = outermost_entry.inner_entries
        self.cf_assignments = outermost_entry.cf_assignments
        self.cf_references = outermost_entry.cf_references
        self.overloaded_alternatives = outermost_entry.overloaded_alternatives
        self.is_cpp_optional = outermost_entry.is_cpp_optional
        self.inner_entries.append(self)

    def __getattr__(self, name):
        if name.startswith('__'):
            # we wouldn't have been called if it was there
            raise AttributeError(name)
        return getattr(self.defining_entry, name)

    def all_entries(self):
        return self.defining_entry.all_entries()


class Scope(object):
    # name              string             Unqualified name
    # outer_scope       Scope or None      Enclosing scope
    # entries           {string : Entry}   Python name to entry, non-types
    # const_entries     [Entry]            Constant entries
    # type_entries      [Entry]            Struct/union/enum/typedef/exttype entries
    # sue_entries       [Entry]            Struct/union/enum entries
    # arg_entries       [Entry]            Function argument entries
    # var_entries       [Entry]            User-defined variable entries
    # pyfunc_entries    [Entry]            Python function entries
    # cfunc_entries     [Entry]            C function entries
    # c_class_entries   [Entry]            All extension type entries
    # cname_to_entry    {string : Entry}   Temp cname to entry mapping
    # return_type       PyrexType or None  Return type of function owning scope
    # is_builtin_scope  boolean            Is the builtin scope of Python/Cython
    # is_py_class_scope boolean            Is a Python class scope
    # is_c_class_scope  boolean            Is an extension type scope
    # is_local_scope    boolean            Is a local (i.e. function/method/generator) scope
    # is_closure_scope  boolean            Is a closure scope
    # is_generator_expression_scope boolean   A subset of closure scope used for generator expressions
    # is_passthrough    boolean            Outer scope is passed directly
    # is_cpp_class_scope  boolean          Is a C++ class scope
    # is_property_scope boolean            Is a extension type property scope
    # is_c_dataclass_scope     boolean or "frozen"  is a cython.dataclasses.dataclass
    # scope_prefix      string             Disambiguator for C names
    # in_cinclude       boolean            Suppress C declaration code
    # qualified_name    string             "modname" or "modname.classname"
    #                                        Python strings in this scope
    # nogil             boolean            In a nogil section
    # directives        dict               Helper variable for the recursive
    #                                      analysis, contains directive values.
    # is_internal       boolean            Is only used internally (simpler setup)
    # scope_predefined_names  list of str   Class variable containing special names defined by
    #                                      this type of scope (e.g. __builtins__, __qualname__)

    is_builtin_scope = 0
    is_py_class_scope = 0
    is_c_class_scope = 0
    is_closure_scope = 0
    is_local_scope = False
    is_generator_expression_scope = 0
    is_comprehension_scope = 0
    is_passthrough = 0
    is_cpp_class_scope = 0
    is_property_scope = 0
    is_module_scope = 0
    is_c_dataclass_scope = False
    is_internal = 0
    scope_prefix = ""
    in_cinclude = 0
    nogil = 0
    fused_to_specific = None
    return_type = None
    scope_predefined_names = []
    # Do ambiguous type names like 'int' and 'float' refer to the C types? (Otherwise, Python types.)
    in_c_type_context = True

    def __init__(self, name, outer_scope, parent_scope):
        # The outer_scope is the next scope in the lookup chain.
        # The parent_scope is used to derive the qualified name of this scope.
        self.name = name
        self.outer_scope = outer_scope
        self.parent_scope = parent_scope
        mangled_name = "%d%s_" % (len(name), name.replace('.', '_dot_'))
        qual_scope = self.qualifying_scope()
        if qual_scope:
            self.qualified_name = qual_scope.qualify_name(name)
            self.scope_prefix = qual_scope.scope_prefix + mangled_name
        else:
            self.qualified_name = EncodedString(name)
            self.scope_prefix = mangled_name
        self.entries = {}
        self.subscopes = set()
        self.const_entries = []
        self.type_entries = []
        self.sue_entries = []
        self.arg_entries = []
        self.var_entries = []
        self.pyfunc_entries = []
        self.cfunc_entries = []
        self.c_class_entries = []
        self.defined_c_classes = []
        self.imported_c_classes = {}
        self.cname_to_entry = {}
        self.identifier_to_entry = {}
        self.num_to_entry = {}
        self.obj_to_entry = {}
        self.buffer_entries = []
        self.lambda_defs = []
        self.id_counters = {}
        for var_name in self.scope_predefined_names:
            self.declare_var(EncodedString(var_name), py_object_type, pos=None)

    def __deepcopy__(self, memo):
        return self

    def merge_in(self, other, merge_unused=True, allowlist=None):
        # Use with care...
        entries = []
        for name, entry in other.entries.items():
            if not allowlist or name in allowlist:
                if entry.used or merge_unused:
                    entries.append((name, entry))

        self.entries.update(entries)

        for attr in ('const_entries',
                     'type_entries',
                     'sue_entries',
                     'arg_entries',
                     'var_entries',
                     'pyfunc_entries',
                     'cfunc_entries',
                     'c_class_entries'):
            self_entries = getattr(self, attr)
            names = set(e.name for e in self_entries)
            for entry in getattr(other, attr):
                if (entry.used or merge_unused) and entry.name not in names:
                    self_entries.append(entry)

    def __str__(self):
        return "<%s %s>" % (self.__class__.__name__, self.qualified_name)

    def qualifying_scope(self):
        return self.parent_scope

    def mangle(self, prefix, name = None):
        if name:
            return punycodify_name("%s%s%s" % (prefix, self.scope_prefix, name))
        else:
            return self.parent_scope.mangle(prefix, self.name)

    def mangle_internal(self, name):
        # Mangle an internal name so as not to clash with any
        # user-defined name in this scope.
        prefix = "%s%s_" % (Naming.pyrex_prefix, name)
        return self.mangle(prefix)
        #return self.parent_scope.mangle(prefix, self.name)

    def mangle_class_private_name(self, name):
        if self.parent_scope:
            return self.parent_scope.mangle_class_private_name(name)
        return name

    def next_id(self, name=None):
        # Return a cname fragment that is unique for this module
        counters = self.global_scope().id_counters
        try:
            count = counters[name] + 1
        except KeyError:
            count = 0
        counters[name] = count
        if name:
            if not count:
                # unique names don't need a suffix, reoccurrences will get one
                return name
            return '%s%d' % (name, count)
        else:
            return '%d' % count

    def global_scope(self):
        """ Return the module-level scope containing this scope. """
        return self.outer_scope.global_scope()

    def builtin_scope(self):
        """ Return the module-level scope containing this scope. """
        return self.outer_scope.builtin_scope()

    def iter_local_scopes(self):
        yield self
        if self.subscopes:
            for scope in sorted(self.subscopes, key=operator.attrgetter('scope_prefix')):
                yield scope

    @try_finally_contextmanager
    def new_c_type_context(self, in_c_type_context=None):
        old_c_type_context = self.in_c_type_context
        if in_c_type_context is not None:
            self.in_c_type_context = in_c_type_context
        yield
        self.in_c_type_context = old_c_type_context

    def declare(self, name, cname, type, pos, visibility, shadow = 0, is_type = 0, create_wrapper = 0):
        # Create new entry, and add to dictionary if
        # name is not None. Reports a warning if already
        # declared.
        if type.is_buffer and not isinstance(self, LocalScope):  # and not is_type:
            error(pos, 'Buffer types only allowed as function local variables')
        if not self.in_cinclude and cname and re.match("^_[_A-Z]+$", cname):
            # See https://www.gnu.org/software/libc/manual/html_node/Reserved-Names.html#Reserved-Names
            warning(pos, "'%s' is a reserved name in C." % cname, -1)

        entries = self.entries
        if name and name in entries and not shadow and not self.is_builtin_scope:
            old_entry = entries[name]

            # Reject redeclared C++ functions only if they have the same type signature.
            cpp_override_allowed = False
            if type.is_cfunction and old_entry.type.is_cfunction and self.is_cpp():
                for alt_entry in old_entry.all_alternatives():
                    if type == alt_entry.type:
                        if name == '<init>' and not type.args:
                            # Cython pre-declares the no-args constructor - allow later user definitions.
                            cpp_override_allowed = True
                        break
                else:
                    cpp_override_allowed = True

            if cpp_override_allowed:
                # C++ function/method overrides with different signatures are ok.
                pass
            elif self.is_cpp_class_scope and entries[name].is_inherited:
                # Likewise ignore inherited classes.
                pass
            elif visibility == 'extern':
                # Silenced outside of "cdef extern" blocks, until we have a safe way to
                # prevent pxd-defined cpdef functions from ending up here.
                warning(pos, "'%s' redeclared " % name, 1 if self.in_cinclude else 0)
            elif visibility != 'ignore':
                error(pos, "'%s' redeclared " % name)
                entries[name].already_declared_here()
        entry = Entry(name, cname, type, pos = pos)
        entry.in_cinclude = self.in_cinclude
        entry.create_wrapper = create_wrapper
        if name:
            entry.qualified_name = self.qualify_name(name)
#            if name in entries and self.is_cpp():
#                entries[name].overloaded_alternatives.append(entry)
#            else:
#                entries[name] = entry
            if not shadow:
                entries[name] = entry

        if type.is_memoryviewslice:
            entry.init = type.default_value

        entry.scope = self
        entry.visibility = visibility
        return entry

    def qualify_name(self, name):
        return EncodedString("%s.%s" % (self.qualified_name, name))

    def declare_const(self, name, type, value, pos, cname = None, visibility = 'private', api = 0, create_wrapper = 0):
        # Add an entry for a named constant.
        if not cname:
            if self.in_cinclude or (visibility == 'public' or api):
                cname = name
            else:
                cname = self.mangle(Naming.enum_prefix, name)
        entry = self.declare(name, cname, type, pos, visibility, create_wrapper = create_wrapper)
        entry.is_const = 1
        entry.value_node = value
        return entry

    def declare_type(self, name, type, pos,
            cname = None, visibility = 'private', api = 0, defining = 1,
            shadow = 0, template = 0):
        # Add an entry for a type definition.
        if not cname:
            cname = name
        entry = self.declare(name, cname, type, pos, visibility, shadow,
                             is_type=True)
        entry.is_type = 1
        entry.api = api
        if defining:
            self.type_entries.append(entry)

        # don't replace an entry that's already set
        if not template and getattr(type, "entry", None) is None:
            type.entry = entry

        # here we would set as_variable to an object representing this type
        return entry

    def declare_typedef(self, name, base_type, pos, cname = None,
                        visibility = 'private', api = 0):
        if not cname:
            if self.in_cinclude or (visibility != 'private' or api):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        try:
            if self.is_cpp_class_scope:
                namespace = self.outer_scope.lookup(self.name).type
            else:
                namespace = None
            type = PyrexTypes.create_typedef_type(name, base_type, cname,
                                                  (visibility == 'extern'),
                                                  namespace)
        except ValueError as e:
            error(pos, e.args[0])
            type = PyrexTypes.error_type
        entry = self.declare_type(name, type, pos, cname,
                                  visibility = visibility, api = api)
        type.qualified_name = entry.qualified_name
        return entry

    def declare_struct_or_union(self, name, kind, scope,
                                typedef_flag, pos, cname = None,
                                visibility = 'private', api = 0,
                                packed = False):
        # Add an entry for a struct or union definition.
        if not cname:
            if self.in_cinclude or (visibility == 'public' or api):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        entry = self.lookup_here(name)
        if not entry:
            in_cpp = self.is_cpp()
            type = PyrexTypes.CStructOrUnionType(
                name, kind, scope, typedef_flag, cname, packed,
                in_cpp = in_cpp)
            entry = self.declare_type(name, type, pos, cname,
                visibility = visibility, api = api,
                defining = scope is not None)
            self.sue_entries.append(entry)
            type.entry = entry
        else:
            if not (entry.is_type and entry.type.is_struct_or_union
                    and entry.type.kind == kind):
                warning(pos, "'%s' redeclared  " % name, 0)
            elif scope and entry.type.scope:
                warning(pos, "'%s' already defined  (ignoring second definition)" % name, 0)
            else:
                self.check_previous_typedef_flag(entry, typedef_flag, pos)
                self.check_previous_visibility(entry, visibility, pos)
                if scope:
                    entry.type.scope = scope
                    self.type_entries.append(entry)
        if self.is_cpp_class_scope:
            entry.type.namespace = self.outer_scope.lookup(self.name).type
        return entry

    def declare_cpp_class(self, name, scope,
            pos, cname = None, base_classes = (),
            visibility = 'extern', templates = None):
        if cname is None:
            if self.in_cinclude or (visibility != 'private'):
                cname = name
            else:
                cname = self.mangle(Naming.type_prefix, name)
        base_classes = list(base_classes)
        entry = self.lookup_here(name)
        if not entry:
            type = PyrexTypes.CppClassType(
                name, scope, cname, base_classes, templates = templates)
            entry = self.declare_type(name, type, pos, cname,
                visibility = visibility, defining = scope is not None)
            self.sue_entries.append(entry)
        else:
            if not (entry.is_type and entry.type.is_cpp_class):
                error(pos, "'%s' redeclared " % name)
                entry.already_declared_here()
                return None
            elif scope and entry.type.scope:
                warning(pos, "'%s' already defined  (ignoring second definition)" % name, 0)
            else:
                if scope:
                    entry.type.scope = scope
                    self.type_entries.append(entry)
            if base_classes:
                if entry.type.base_classes and entry.type.base_classes != base_classes:
                    error(pos, "Base type does not match previous declaration")
                    entry.already_declared_here()
                else:
                    entry.type.base_classes = base_classes
            if templates or entry.type.templates:
                if templates != entry.type.templates:
                    error(pos, "Template parameters do not match previous declaration")
                    entry.already_declared_here()

        def declare_inherited_attributes(entry, base_classes):
            for base_class in base_classes:
                if base_class is PyrexTypes.error_type:
                    continue
                if base_class.scope is None:
                    error(pos, "Cannot inherit from incomplete type")
                else:
                    declare_inherited_attributes(entry, base_class.base_classes)
                    entry.type.scope.declare_inherited_cpp_attributes(base_class)
        if scope:
            declare_inherited_attributes(entry, base_classes)
            scope.declare_var(name="this", cname="this", type=PyrexTypes.CPtrType(entry.type), pos=entry.pos)
        if self.is_cpp_class_scope:
            entry.type.namespace = self.outer_scope.lookup(self.name).type
        return entry

    def check_previous_typedef_flag(self, entry, typedef_flag, pos):
        if typedef_flag != entry.type.typedef_flag:
            error(pos, "'%s' previously declared using '%s'" % (
                entry.name, ("cdef", "ctypedef")[entry.type.typedef_flag]))

    def check_previous_visibility(self, entry, visibility, pos):
        if entry.visibility != visibility:
            error(pos, "'%s' previously declared as '%s'" % (
                entry.name, entry.visibility))

    def declare_enum(self, name, pos, cname, scoped, typedef_flag,
            visibility='private', api=0, create_wrapper=0, doc=None):
        if name:
            if not cname:
                if (self.in_cinclude or visibility == 'public'
                        or visibility == 'extern' or api):
                    cname = name
                else:
                    cname = self.mangle(Naming.type_prefix, name)
            if self.is_cpp_class_scope:
                namespace = self.outer_scope.lookup(self.name).type
            else:
                namespace = None

            if scoped:
                type = PyrexTypes.CppScopedEnumType(name, cname, namespace, doc=doc)
            else:
                type = PyrexTypes.CEnumType(name, cname, typedef_flag, namespace, doc=doc)
        else:
            type = PyrexTypes.c_anon_enum_type
        entry = self.declare_type(name, type, pos, cname = cname,
            visibility = visibility, api = api)
        if scoped:
            entry.utility_code = Code.UtilityCode.load_cached("EnumClassDecl", "CppSupport.cpp")
            self.use_entry_utility_code(entry)
        entry.create_wrapper = create_wrapper
        entry.enum_values = []

        self.sue_entries.append(entry)
        return entry

    def declare_tuple_type(self, pos, components):
        return self.outer_scope.declare_tuple_type(pos, components)

    def declare_var(self, name, type, pos,
                    cname=None, visibility='private',
                    api=False, in_pxd=False, is_cdef=False, pytyping_modifiers=None):
        # Add an entry for a variable.
        if not cname:
            if visibility != 'private' or api:
                cname = name
            else:
                cname = self.mangle(Naming.var_prefix, name)
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_variable = 1
        if type.is_cpp_class and visibility != 'extern':
            if self.directives['cpp_locals']:
                entry.make_cpp_optional()
            else:
                type.check_nullary_constructor(pos)
        if in_pxd and visibility != 'extern':
            entry.defined_in_pxd = 1
            entry.used = 1
        if api:
            entry.api = 1
            entry.used = 1
        if pytyping_modifiers:
            entry.pytyping_modifiers = pytyping_modifiers
        return entry

    def _reject_pytyping_modifiers(self, pos, modifiers, allowed=()):
        if not modifiers:
            return
        for modifier in modifiers:
            if modifier not in allowed:
                error(pos, "Modifier '%s' is not allowed here." % modifier)

    def declare_assignment_expression_target(self, name, type, pos):
        # In most cases declares the variable as normal.
        # For generator expressions and comprehensions the variable is declared in their parent
        return self.declare_var(name, type, pos)

    def declare_builtin(self, name, pos):
        name = self.mangle_class_private_name(name)
        return self.outer_scope.declare_builtin(name, pos)

    def _declare_pyfunction(self, name, pos, visibility='extern', entry=None):
        if entry and not entry.type.is_cfunction:
            error(pos, "'%s' already declared" % name)
            error(entry.pos, "Previous declaration is here")
        entry = self.declare_var(name, py_object_type, pos, visibility=visibility)
        entry.signature = pyfunction_signature
        self.pyfunc_entries.append(entry)
        return entry

    def declare_pyfunction(self, name, pos, allow_redefine=False, visibility='extern'):
        # Add an entry for a Python function.
        entry = self.lookup_here(name)
        if not allow_redefine:
            return self._declare_pyfunction(name, pos, visibility=visibility, entry=entry)
        if entry:
            if entry.type.is_unspecified:
                entry.type = py_object_type
            elif entry.type is not py_object_type:
                return self._declare_pyfunction(name, pos, visibility=visibility, entry=entry)
        else:  # declare entry stub
            self.declare_var(name, py_object_type, pos, visibility=visibility)
        entry = self.declare_var(None, py_object_type, pos,
                                 cname=name, visibility='private')
        entry.name = EncodedString(name)
        entry.qualified_name = self.qualify_name(name)
        entry.signature = pyfunction_signature
        entry.is_anonymous = True
        return entry

    def declare_lambda_function(self, lambda_name, pos):
        # Add an entry for an anonymous Python function.
        func_cname = self.mangle(Naming.lambda_func_prefix + u'funcdef_', lambda_name)
        pymethdef_cname = self.mangle(Naming.lambda_func_prefix + u'methdef_', lambda_name)
        qualified_name = self.qualify_name(lambda_name)

        entry = self.declare(None, func_cname, py_object_type, pos, 'private')
        entry.name = EncodedString(lambda_name)
        entry.qualified_name = qualified_name
        entry.pymethdef_cname = pymethdef_cname
        entry.func_cname = func_cname
        entry.signature = pyfunction_signature
        entry.is_anonymous = True
        return entry

    def add_lambda_def(self, def_node):
        self.lambda_defs.append(def_node)

    def register_pyfunction(self, entry):
        self.pyfunc_entries.append(entry)

    def declare_cfunction(self, name, type, pos,
                          cname=None, visibility='private', api=0, in_pxd=0,
                          defining=0, modifiers=(), utility_code=None, overridable=False):
        # Add an entry for a C function.
        if not cname:
            if visibility != 'private' or api:
                cname = name
            else:
                cname = self.mangle(Naming.func_prefix, name)
        entry = self.lookup_here(name)
        if entry:
            if not in_pxd and visibility != entry.visibility and visibility == 'extern':
                # Previously declared, but now extern => treat this
                # as implementing the function, using the new cname
                defining = True
                visibility = entry.visibility
                entry.cname = cname
                entry.func_cname = cname
            if visibility != 'private' and visibility != entry.visibility:
                warning(pos, "Function '%s' previously declared as '%s', now as '%s'" % (
                    name, entry.visibility, visibility), 1)
            if overridable != entry.is_overridable:
                warning(pos, "Function '%s' previously declared as '%s'" % (
                    name, 'cpdef' if overridable else 'cdef'), 1)
            if entry.type.same_as(type):
                # Fix with_gil vs nogil.
                entry.type = entry.type.with_with_gil(type.with_gil)
            else:
                if visibility == 'extern' and entry.visibility == 'extern':
                    can_override = self.is_builtin_scope
                    if self.is_cpp():
                        can_override = True
                    elif cname and not can_override:
                        # if all alternatives have different cnames,
                        # it's safe to allow signature overrides
                        for alt_entry in entry.all_alternatives():
                            if not alt_entry.cname or cname == alt_entry.cname:
                                break  # cname not unique!
                        else:
                            can_override = True
                    if can_override:
                        temp = self.add_cfunction(name, type, pos, cname, visibility, modifiers)
                        temp.overloaded_alternatives = entry.all_alternatives()
                        entry = temp
                    else:
                        warning(pos, "Function signature does not match previous declaration", 1)
                        entry.type = type
                elif not in_pxd and entry.defined_in_pxd and type.compatible_signature_with(entry.type):
                    # TODO: check that this was done by a signature optimisation and not a user error.
                    #warning(pos, "Function signature does not match previous declaration", 1)
                    entry.type = type
                else:
                    error(pos, "Function signature does not match previous declaration")
        else:
            entry = self.add_cfunction(name, type, pos, cname, visibility, modifiers)
            entry.func_cname = cname
            entry.is_overridable = overridable
        if in_pxd and visibility != 'extern':
            entry.defined_in_pxd = 1
        if api:
            entry.api = 1
        if not defining and not in_pxd and visibility != 'extern':
            error(pos, "Non-extern C function '%s' declared but not defined" % name)
        if defining:
            entry.is_implemented = True
        if modifiers:
            entry.func_modifiers = modifiers
        if utility_code:
            assert not entry.utility_code, "duplicate utility code definition in entry %s (%s)" % (name, cname)
            entry.utility_code = utility_code
        if overridable:
            # names of cpdef functions can be used as variables and can be assigned to
            var_entry = Entry(name, cname, py_object_type)   # FIXME: cname?
            var_entry.qualified_name = self.qualify_name(name)
            var_entry.is_variable = 1
            var_entry.is_pyglobal = 1
            var_entry.scope = entry.scope
            entry.as_variable = var_entry
        type.entry = entry
        return entry

    def declare_cgetter(self, name, return_type, pos=None, cname=None,
                        visibility="private", modifiers=(), defining=False, **cfunc_type_config):
        assert all(
            k in ('exception_value', 'exception_check', 'nogil', 'with_gil', 'is_const_method', 'is_static_method')
            for k in cfunc_type_config
        )
        cfunc_type = PyrexTypes.CFuncType(
            return_type,
            [PyrexTypes.CFuncTypeArg("self", self.parent_type, None)],
            **cfunc_type_config)
        entry = self.declare_cfunction(
            name, cfunc_type, pos, cname=None, visibility=visibility, modifiers=modifiers, defining=defining)
        entry.is_cgetter = True
        if cname is not None:
            entry.func_cname = cname
        return entry

    def add_cfunction(self, name, type, pos, cname, visibility, modifiers, inherited=False):
        # Add a C function entry without giving it a func_cname.
        entry = self.declare(name, cname, type, pos, visibility)
        entry.is_cfunction = 1
        if modifiers:
            entry.func_modifiers = modifiers
        if inherited or type.is_fused:
            self.cfunc_entries.append(entry)
        else:
            # For backwards compatibility reasons, we must keep all non-fused methods
            # before all fused methods, but separately for each type.
            i = len(self.cfunc_entries)
            for cfunc_entry in reversed(self.cfunc_entries):
                if cfunc_entry.is_inherited or not cfunc_entry.type.is_fused:
                    break
                i -= 1
            self.cfunc_entries.insert(i, entry)
        return entry

    def find(self, name, pos):
        # Look up name, report error if not found.
        entry = self.lookup(name)
        if entry:
            return entry
        else:
            error(pos, "'%s' is not declared" % name)

    def find_imported_module(self, path, pos):
        # Look up qualified name, must be a module, report error if not found.
        # Path is a list of names.
        scope = self
        for name in path:
            entry = scope.find(name, pos)
            if not entry:
                return None
            if entry.as_module:
                scope = entry.as_module
            else:
                error(pos, "'%s' is not a cimported module" % '.'.join(path))
                return None
        return scope

    def lookup(self, name):
        # Look up name in this scope or an enclosing one.
        # Return None if not found.

        mangled_name = self.mangle_class_private_name(name)
        entry = (self.lookup_here(name)  # lookup here also does mangling