BUG: Fix CI failure by adding symbols to be exported on Cygwin

There are two types of Cython in the Cygwin environment.
One is a Cygwin package's Cython,
which does not add a `__declspec(dllexport)` attribute to symbols
due to its custom patch.
The other is Cython, which is installed with pip and has no custom patches,
so the symbols are added the `__declspec(dllexport)` attribute.

Since CI uses symbols in distributions.c by cffi, we need to export them.
The commit b797a0cb97a8a9e7e36962dc8c37c075967aa88b exports the symbols
by adding the `__declspec(dllexport)` attribute to them.
However, in the Cygwin package's Cython environment,
the symbols required for import are not exported
and the module cannot be imported.
https://cygwin.com/pipermail/cygwin/2022-January/250481.html

By the previous commit, the `__declspec(dllexport)` attribute is removed,
so in the environment, the required symbols are exported
and the module can be imported.
However, on the other hand, in the pip-installed Cython environment,
the symbols used by cffi are not exported, so CI failed.

This commit exports the symbols without `__declspec(dllexport)`
for use by cffi.
It exports both the symbols required for import
and the symbols used for cffi,
regardless of which Cython environment is used.

1 files changed, 7 insertions, 0 deletions

diff --git a/numpy/random/setup.py b/numpy/random/setup.py
index 866c0cb2f..01808e83c 100644
--- a/numpy/random/setup.py
+++ b/numpy/random/setup.py
@@ -50,6 +50,13 @@ def configuration(parent_package='', top_path=None):
         # Some bit generators require c99
         EXTRA_COMPILE_ARGS += ['-std=c99']
 
+    if sys.platform == 'cygwin':
+        # Export symbols without __declspec(dllexport) for using by cython.
+        # Using __declspec(dllexport) does not export other necessary symbols
+        # in Cygwin package's Cython enviroment, making it impossible to
+        # import modules.
+        EXTRA_LINK_ARGS += ['-Wl,--export-all-symbols']
+
     # Use legacy integer variable sizes
     LEGACY_DEFS = [('NP_RANDOM_LEGACY', '1')]
     PCG64_DEFS = []