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[python] Anchor the cpyrt header probe on the extension module #25

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[python] Anchor the cpyrt header probe on the extension module #25

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85 changes: 17 additions & 68 deletions python/cppjit/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@
]

import ctypes
import importlib.util
import os
import sys
import sysconfig
Expand Down Expand Up @@ -334,82 +335,30 @@ def add_library_path(path):
if os.path.exists(apipath) and os.path.exists(os.path.join(apipath, "Python.h")):
add_include_path(apipath)

# add access to extra headers for dispatcher (cpyrt only (?))
# add access to the cpyrt dispatcher API headers, which install next to the
# extension module; anchoring on the extension resolves editable and regular
# installs alike. CPPJIT_API_PATH overrides ("none" disables the lookup).
if not ispypy:
try:
apipath_extra = os.environ["CPPJIT_API_PATH"]
apipath_extra = os.environ.get("CPPJIT_API_PATH")
if apipath_extra:
if os.path.basename(apipath_extra) == "cpyrt":
apipath_extra = os.path.dirname(apipath_extra)
except KeyError:
apipath_extra = None

if apipath_extra is None:
try:
import pkg_resources as pr

d = pr.get_distribution("cpyrt")
for line in d.get_metadata_lines("RECORD"):
if "API.h" in line:
part = line[0 : line.find(",")]

ape = os.path.join(d.location, part)
if os.path.exists(ape):
apipath_extra = os.path.dirname(os.path.dirname(ape))

del part, d, pr
except Exception:
pass

if apipath_extra is None:
# for the monorepo: headers are at cppjit_backend/include/
_cppjit_inc = os.path.join(
os.path.dirname(os.path.dirname(__file__)), "cppjit_backend", "include"
)
if os.path.exists(os.path.join(_cppjit_inc, "cpyrt")):
apipath_extra = _cppjit_inc
del _cppjit_inc

if apipath_extra is None:
ldversion = sysconfig.get_config_var("LDVERSION")
if not ldversion:
ldversion = sys.version[:3]
else:
_spec = importlib.util.find_spec("libcppjit")
if _spec is not None and _spec.origin:
apipath_extra = os.path.join(
os.path.dirname(_spec.origin), "cppjit_backend", "include"
)
del _spec

@Vipul-Cariappa Vipul-Cariappa Aug 18, 2026

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Suggested change
del _spec

Why do we need to explicitly delete here? Wouldn't the GC collect it if it doesn't have any active references?

@aaronj0 aaronj0 Aug 18, 2026 •
edited
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This is in module scope, the GC will only collect _spec once nothing references it, but here the module itself keeps a reference for the process lifetime (the assignment retains it as cppjit._spec), and it shows up in dir(cppjit). The del drops that. We already do del on apipath_extra, include_path, apipath, ispypy for the same reason (also only required at init time and not a part of dir(cppjit))


apipath_extra = os.path.join(
os.path.dirname(apipath), "site", "python" + ldversion
)
if not os.path.exists(os.path.join(apipath_extra, "cpyrt")):
import glob

import libcppjit

ape = os.path.dirname(libcppjit.__file__)
# a "normal" structure finds the include directory up to 3 levels up,
# ie. dropping lib/pythonx.y[md]/site-packages
for i in range(3):
if os.path.exists(os.path.join(ape, "include")):
break
ape = os.path.dirname(ape)

ape = os.path.join(ape, "include")
if os.path.exists(os.path.join(ape, "cpyrt")):
apipath_extra = ape
else:
# add back pythonx.y or site/pythonx.y if present
for p in glob.glob(
os.path.join(ape, "python" + sys.version[:3] + "*")
) + glob.glob(os.path.join(ape, "*", "python" + sys.version[:3] + "*")):
if os.path.exists(os.path.join(p, "cpyrt")):
apipath_extra = p
break

if apipath_extra.lower() != "none":
if not os.path.exists(os.path.join(apipath_extra, "cpyrt")):
if apipath_extra and apipath_extra.lower() != "none":
if os.path.isdir(os.path.join(apipath_extra, "cpyrt")):
add_include_path(apipath_extra)
else:
warnings.warn(
"cpyrt API not found (tried: %s); set CPPJIT_API_PATH envar to the 'cpyrt' API directory to fix"
% apipath_extra
)
else:
add_include_path(apipath_extra)

del apipath_extra

Expand Down
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