Delete historical USE_LIMITED_API helper

Author: ngoldbaum

src/cffi/_cffi_include.h

@@ -13,16 +13,6 @@
    In that case, we guess what pyconfig.h will do to the macros above,
    and check our guess after the #include.
 
-   Note that on Windows, with CPython 3.x, you need >= 3.5 and virtualenv
-   version >= 16.0.0.  With older versions of either, you don't get a
-   copy of PYTHON3.DLL in the virtualenv.  We can't check the version of
-   CPython *before* we even include pyconfig.h.  ffi.set_source() puts
-   a ``#define _CFFI_NO_LIMITED_API'' at the start of this file if it is
-   running on Windows < 3.5, as an attempt at fixing it, but that's
-   arguably wrong because it may not be the target version of Python.
-   Still better than nothing I guess.  As another workaround, you can
-   remove the definition of Py_LIMITED_API here.
-
    See also 'py_limited_api' in cffi/setuptools_ext.py.
 */
 #if !defined(_CFFI_USE_EMBEDDING) && !defined(Py_LIMITED_API)

src/cffi/recompiler.py

@@ -7,12 +7,6 @@
 VERSION_EMBEDDED = 0x2701
 VERSION_CHAR16CHAR32 = 0x2801
 
-# Must not depend on the interpreter running the generator: the generated
-# source may be compiled for a different one (see cffi-gen-src).  Decisions
-# about the target, such as abi3t support, are made at compile time in
-# _cffi_include.h.
-USE_LIMITED_API = (sys.platform != 'win32' or sys.version_info < (3, 0) or
-                   sys.version_info >= (3, 5))
 
 class GlobalExpr:
     def __init__(self, name, address, type_op, size=0, check_value=0):
@@ -307,8 +301,6 @@ def write_c_source_to_f(self, f, preamble):
         prnt = self._prnt
         if self.ffi._embedding is not None:
             prnt('#define _CFFI_USE_EMBEDDING')
-        if not USE_LIMITED_API:
-            prnt('#define _CFFI_NO_LIMITED_API')
         #
         # first the '#include' (actually done by inlining the file's content)
         lines = self._rel_readlines('_cffi_include.h')

src/cffi/setuptools_ext.py

@@ -82,19 +82,10 @@ def _set_py_limited_api(Extension, kwds):
     it doesn't so far, creating troubles.  That's why we check
     for "not hasattr(sys, 'gettotalrefcount')" (the 2.7 compatible equivalent
     of 'd' not in sys.abiflags). (http://bugs.python.org/issue28401)
-
-    On Windows, with CPython <= 3.4, it's better not to use py_limited_api
-    because virtualenv *still* doesn't copy PYTHON3.DLL on these versions.
-    Recently (2020) we started shipping only >= 3.5 wheels, though.  So
-    we'll give it another try and set py_limited_api on Windows >= 3.5.
     """
     from cffi._shimmed_dist_utils import log
-    from cffi import recompiler
 
     if ('py_limited_api' not in kwds and not hasattr(sys, 'gettotalrefcount')
-            and recompiler.USE_LIMITED_API
-            # unlike USE_LIMITED_API, checking the running interpreter is
-            # correct here: setuptools generates and compiles in one process
             and (not sysconfig.get_config_var("Py_GIL_DISABLED")
                  or sys.version_info >= (3, 15))):
         import setuptools

testing/cffi1/test_recompiler.py

@@ -2600,7 +2600,6 @@ def test_emit_c_code_is_interpreter_independent():
     # the emitted source must be a pure function of the FFI object, with
     # no #defines derived from the interpreter running the generator
     import io
-    assert recompiler.USE_LIMITED_API   # constant on all supported Pythons
     ffi = FFI()
     ffi.cdef("int ff_interp_indep(int);")
     ffi.set_source("_CFFI_interp_indep",