fix: Add `libs/python3.lib` to libpython target for SABI builds on Windows (#1820)
When targeting the Python Stable ABI on Windows (by setting the
Py_LIMITED_API macro to a Python minimum version hex), the unversioned
python3.lib needs to be linked instead of the versioned one (e.g.
python38.lib for Python 3.8).
Python's own config sets the library to link by default in a header
called pyconfig.h
(https://github.com/python/cpython/blob/9cc9e277254023c0ca08e1a9e379fd89475ca9c2/PC/pyconfig.h#L270),
which prompts the linker to search for python3.lib if a stable ABI
extension is built using `@rules_python` toolchains.
Since this library is not exported on Windows in the
`python_repository()` rule, building Python C++ extensions with
rules_python toolchains fails in the linking step, because the library
is never copied. Consequently, it is added now to allow Python SABI
extensions to be built (and linked) on Windows with `@rules_python`.
Since Python takes responsibility for linking the correct lib on
Windows, and never both at the same time, no other changes are made.
---------
Co-authored-by: Richard Levasseur <richardlev@gmail.com>
Co-authored-by: Richard Levasseur <rlevasseur@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc66afa..37a9e71 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -95,6 +95,9 @@
([2169](https://github.com/bazelbuild/rules_python/issues/2169)).
* (workspace) Corrected protobuf's name to com_google_protobuf, the name is
hardcoded in Bazel, WORKSPACE mode.
+* (repositories): Add libs/python3.lib and pythonXY.dll to the `libpython` target
+ defined by a repository template. This enables stable ABI builds of Python extensions
+ on Windows (by defining Py_LIMITED_API).
{#v0-0-0-added}
### Added
diff --git a/python/private/hermetic_runtime_repo_setup.bzl b/python/private/hermetic_runtime_repo_setup.bzl
index d041be5..64d721e 100644
--- a/python/private/hermetic_runtime_repo_setup.bzl
+++ b/python/private/hermetic_runtime_repo_setup.bzl
@@ -89,6 +89,14 @@
}),
system_provided = True,
)
+ cc_import(
+ name = "abi3_interface",
+ interface_library = select({
+ _IS_FREETHREADED: "libs/python3t.lib",
+ "//conditions:default": "libs/python3.lib",
+ }),
+ system_provided = True,
+ )
native.filegroup(
name = "includes",
@@ -97,7 +105,7 @@
cc_library(
name = "python_headers",
deps = select({
- "@bazel_tools//src/conditions:windows": [":interface"],
+ "@bazel_tools//src/conditions:windows": [":interface", ":abi3_interface"],
"//conditions:default": None,
}),
hdrs = [":includes"],
@@ -156,15 +164,22 @@
"lib/libpython{major}.{minor}t.dylib".format(**version_dict),
],
":is_freethreaded_windows": [
- "python3.dll",
+ "python3t.dll",
+ "python{major}{minor}t.dll".format(**version_dict),
"libs/python{major}{minor}t.lib".format(**version_dict),
+ "libs/python3t.lib",
],
"@platforms//os:linux": [
"lib/libpython{major}.{minor}.so".format(**version_dict),
"lib/libpython{major}.{minor}.so.1.0".format(**version_dict),
],
"@platforms//os:macos": ["lib/libpython{major}.{minor}.dylib".format(**version_dict)],
- "@platforms//os:windows": ["python3.dll", "libs/python{major}{minor}.lib".format(**version_dict)],
+ "@platforms//os:windows": [
+ "python3.dll",
+ "python{major}{minor}.dll".format(**version_dict),
+ "libs/python{major}{minor}.lib".format(**version_dict),
+ "libs/python3.lib",
+ ],
}),
)
diff --git a/tests/cc/current_py_cc_libs/BUILD.bazel b/tests/cc/current_py_cc_libs/BUILD.bazel
index 2180555..9f33599 100644
--- a/tests/cc/current_py_cc_libs/BUILD.bazel
+++ b/tests/cc/current_py_cc_libs/BUILD.bazel
@@ -33,3 +33,21 @@
"@rules_python//python/cc:current_py_cc_libs",
],
)
+
+# This is technically a headers test, but since the pyconfig.h header
+# designates the appropriate lib to link on Win+MSVC, this test verifies that
+# the expected Windows libraries are all present in the expected location.
+# Since we define the Py_LIMITED_API macro, we expect the linker to go search
+# for libs/python3.lib.
+# buildifier: disable=native-cc
+cc_test(
+ name = "python_libs_linking_windows_test",
+ srcs = ["python_libs_linking_test.cc"],
+ defines = ["Py_LIMITED_API=0x030A0000"],
+ env = {"HELLO": "world"},
+ target_compatible_with = ["@platforms//os:windows"],
+ deps = [
+ "@rules_python//python/cc:current_py_cc_headers",
+ "@rules_python//python/cc:current_py_cc_libs",
+ ],
+)
diff --git a/tests/cc/current_py_cc_libs/python_libs_linking_test.cc b/tests/cc/current_py_cc_libs/python_libs_linking_test.cc
index 1ecce08..2f26a2c 100644
--- a/tests/cc/current_py_cc_libs/python_libs_linking_test.cc
+++ b/tests/cc/current_py_cc_libs/python_libs_linking_test.cc
@@ -12,7 +12,7 @@
// To make it actually run, more custom initialization is necessary.
// See https://docs.python.org/3/c-api/intro.html#embedding-python
Py_Initialize();
- PyRun_SimpleString("print('Hello, world')\n");
+ Py_BytesMain(argc, argv);
Py_Finalize();
return 0;
}
