Merge pull request #20909 from charris/backport-20881

BUG: fix f2py's define for threading when building with Mingw

numpy/f2py/cfuncs.py

@@ -572,18 +572,20 @@
 """
 cppmacros["F2PY_THREAD_LOCAL_DECL"] = """\
 #ifndef F2PY_THREAD_LOCAL_DECL
-#if defined(_MSC_VER) \\
-      || defined(_WIN32) || defined(_WIN64) \\
-      || defined(__MINGW32__) || defined(__MINGW64__)
+#if defined(_MSC_VER)
 #define F2PY_THREAD_LOCAL_DECL __declspec(thread)
+#elif defined(__MINGW32__) || defined(__MINGW64__)
+#define F2PY_THREAD_LOCAL_DECL __thread
 #elif defined(__STDC_VERSION__) \\
       && (__STDC_VERSION__ >= 201112L) \\
       && !defined(__STDC_NO_THREADS__) \\
-      && (!defined(__GLIBC__) || __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 12))
+      && (!defined(__GLIBC__) || __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 12)) \\
+      && !defined(__OpenBSD__)
 /* __STDC_NO_THREADS__ was first defined in a maintenance release of glibc 2.12,
    see https://lists.gnu.org/archive/html/commit-hurd/2012-07/msg00180.html,
    so `!defined(__STDC_NO_THREADS__)` may give false positive for the existence
-   of `threads.h` when using an older release of glibc 2.12 */
+   of `threads.h` when using an older release of glibc 2.12
+   See gh-19437 for details on OpenBSD */
 #include <threads.h>
 #define F2PY_THREAD_LOCAL_DECL thread_local
 #elif defined(__GNUC__) \\