TST: add test package with internal shared libraries, installed in site-packages

Author: rgommers

tests/packages/sharedlib-in-package/meson.build

@@ -0,0 +1,9 @@
+# SPDX-FileCopyrightText: 2022 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+project('sharedlib-in-package', 'c', version: '1.0.0')
+
+py = import('python').find_installation(pure: false)
+
+subdir('mypkg')

tests/packages/sharedlib-in-package/mypkg/__init__.py

@@ -0,0 +1,54 @@
+# SPDX-FileCopyrightText: 2024 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+import os
+import sys
+
+from ._example import example_prod, example_sum
+
+
+# Note: the below function is used in the docs via a literalinclude directive.
+#       When making any changes to this file, please ensure the right set of
+#       lines is pulled into the docs, and adjust the :lines: attribute of
+#       the literalinclude if needed.
+
+
+def _enable_sharedlib_loading():
+    """
+    Ensure the shared libraries in this dir and the `sub` subdir can be loaded
+    on Windows.
+
+    One shared library is installed alongside this ``__init__.py`` file.
+    Windows can load it because it searches for DLLs in the directory a ``.pyd``
+    (Python extension module) is located in. Cygwin does not though. For a
+    shared library in another directory inside the package, Windows also needs
+    a hint.
+
+    This function is Windows-specific due to lack of RPATH support on Windows.
+    It cannot find shared libraries installed within wheels unless we either
+    amend the DLL search path or pre-load the DLL.
+
+    Note that `delvewheel` inserts a similar snippet into the main
+    `__init__.py` of a package when it vendors external shared libraries.
+
+    .. note::
+
+        `os.add_dll_directory` is only available for Python >=3.8, and with
+        the Conda `python` packages only works as advertised for >=3.10.
+        If you require support for older versions, pre-loading the DLL
+        with `ctypes.WinDLL` may be preferred (the SciPy code base has an
+        example of this).
+    """
+    basedir = os.path.dirname(__file__)
+    subdir = os.path.join(basedir, 'sub')
+    if os.name == "nt":
+        os.add_dll_directory(subdir)
+    elif sys.platform == "cygwin":
+        os.environ["PATH"] = f"{os.environ['PATH']}:{basedir}:{subdir}"
+
+
+_enable_sharedlib_loading()
+
+
+__all__ = ['example_prod', 'example_sum']

tests/packages/sharedlib-in-package/mypkg/_examplemod.c

@@ -0,0 +1,51 @@
+// SPDX-FileCopyrightText: 2022 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include <Python.h>
+
+#include "examplelib.h"
+#include "examplelib2.h"
+
+static PyObject* example_sum(PyObject* self, PyObject *args)
+{
+    int a, b;
+    if (!PyArg_ParseTuple(args, "ii", &a, &b)) {
+        return NULL;
+    }
+
+    long result = sum(a, b);
+
+    return PyLong_FromLong(result);
+}
+
+static PyObject* example_prod(PyObject* self, PyObject *args)
+{
+    int a, b;
+    if (!PyArg_ParseTuple(args, "ii", &a, &b)) {
+        return NULL;
+    }
+
+    long result = prod(a, b);
+
+    return PyLong_FromLong(result);
+}
+
+static PyMethodDef methods[] = {
+    {"example_prod", (PyCFunction)example_prod, METH_VARARGS, NULL},
+    {"example_sum", (PyCFunction)example_sum, METH_VARARGS, NULL},
+    {NULL, NULL, 0, NULL},
+};
+
+static struct PyModuleDef module = {
+    PyModuleDef_HEAD_INIT,
+    "_example",
+    NULL,
+    -1,
+    methods,
+};
+
+PyMODINIT_FUNC PyInit__example(void)
+{
+    return PyModule_Create(&module);
+}

tests/packages/sharedlib-in-package/mypkg/examplelib.c

@@ -0,0 +1,9 @@
+// SPDX-FileCopyrightText: 2022 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include "sub/mypkg_dll.h"
+
+MYPKG_DLL int sum(int a, int b) {
+	return a + b;
+}

tests/packages/sharedlib-in-package/mypkg/examplelib.h

@@ -0,0 +1,7 @@
+// SPDX-FileCopyrightText: 2022 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include "sub/mypkg_dll.h"
+
+MYPKG_DLL int sum(int a, int b);

tests/packages/sharedlib-in-package/mypkg/meson.build

@@ -0,0 +1,41 @@
+# SPDX-FileCopyrightText: 2022 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+if meson.get_compiler('c').get_id() in ['msvc', 'clang-cl', 'intel-cl']
+  export_dll_args = ['-DMYPKG_DLL_EXPORTS']
+  import_dll_args = ['-DMYPKG_DLL_IMPORTS']
+else
+  export_dll_args = []
+  import_dll_args = []
+endif
+
+example_lib = shared_library(
+    'examplelib',
+    'examplelib.c',
+    c_args: export_dll_args,
+    install: true,
+    install_dir: py.get_install_dir() / 'mypkg',
+)
+
+example_lib_dep = declare_dependency(
+  compile_args: import_dll_args,
+  link_with: example_lib,
+)
+
+subdir('sub')
+
+py.extension_module(
+    '_example',
+    '_examplemod.c',
+    dependencies: [example_lib_dep, example_lib2_dep],
+    include_directories: 'sub',
+    install: true,
+    subdir: 'mypkg',
+    install_rpath: '$ORIGIN',
+)
+
+py.install_sources(
+    ['__init__.py'],
+    subdir: 'mypkg',
+)

tests/packages/sharedlib-in-package/mypkg/sub/examplelib2.c

@@ -0,0 +1,9 @@
+// SPDX-FileCopyrightText: 2022 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include "mypkg_dll.h"
+
+MYPKG_DLL int prod(int a, int b) {
+	return a * b;
+}

tests/packages/sharedlib-in-package/mypkg/sub/examplelib2.h

@@ -0,0 +1,7 @@
+// SPDX-FileCopyrightText: 2022 The meson-python developers
+//
+// SPDX-License-Identifier: MIT
+
+#include "mypkg_dll.h"
+
+MYPKG_DLL int prod(int a, int b);

tests/packages/sharedlib-in-package/mypkg/sub/meson.build

@@ -0,0 +1,16 @@
+# SPDX-FileCopyrightText: 2022 The meson-python developers
+#
+# SPDX-License-Identifier: MIT
+
+example_lib2 = shared_library(
+    'examplelib2',
+    'examplelib2.c',
+    c_args: export_dll_args,
+    install: true,
+    install_dir: py.get_install_dir() / 'mypkg/sub',
+)
+
+example_lib2_dep = declare_dependency(
+  compile_args: import_dll_args,
+  link_with: example_lib2,
+)

tests/packages/sharedlib-in-package/mypkg/sub/mypkg_dll.h

@@ -0,0 +1,19 @@
+#pragma once
+
+// MYPKG_DLL
+// inspired by https://github.com/abseil/abseil-cpp/blob/20240116.2/absl/base/config.h#L736-L753
+// and https://github.com/scipy/scipy/blob/9ded83b51099eee745418ccbb30196db96c81f3f/scipy/_build_utils/src/scipy_dll.h
+//
+// When building the `examplelib` DLL, this macro expands to `__declspec(dllexport)`
+// so we can annotate symbols appropriately as being exported. When used in
+// headers consuming a DLL, this macro expands to `__declspec(dllimport)` so
+// that consumers know the symbol is defined inside the DLL. In all other cases,
+// the macro expands to nothing.
+// Note: MYPKG_DLL_{EX,IM}PORTS are set in mypkg/meson.build
+#if defined(MYPKG_DLL_EXPORTS)
+    #define MYPKG_DLL __declspec(dllexport)
+#elif defined(MYPKG_DLL_IMPORTS)
+    #define MYPKG_DLL __declspec(dllimport)
+#else
+    #define MYPKG_DLL
+#endif