libgcc: gthr-c11: add weak threads.h impl for gthr-c11

Add a weak threads.h implementation (C11 threads library)
so that gthr-c11.h has something to resolve when linking,
by default.

Signed-off-by: Christopher Friedt <chris@friedt.co>

libgcc/Makefile.in

@@ -436,6 +436,9 @@ LIB2ADD += enable-execute-stack.c
 LIB2ADDEH += $(srcdir)/emutls.c
 LIB2ADDEHSTATIC += $(srcdir)/emutls.c
 LIB2ADDEHSHARED += $(srcdir)/emutls.c
+LIB2ADDEH += $(srcdir)/c11-thrd-weak.c
+LIB2ADDEHSTATIC += $(srcdir)/c11-thrd-weak.c
+LIB2ADDEHSHARED += $(srcdir)/c11-thrd-weak.c
 
 # Library members defined in libgcc2.c.
 lib2funcs = _muldi3 _negdi2 _lshrdi3 _ashldi3 _ashrdi3 _cmpdi2 _ucmpdi2	   \

libgcc/c11-thrd-weak.c

@@ -0,0 +1,234 @@
+/* ISO C11 Standard: 7.26 - Thread support library  <threads.h>.
+   Copyright (C) 2018-2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* weak C11 thread.h implementations to support gthr-c11.h */
+
+#include <threads.h>
+
+#if SUPPORTS_WEAK
+
+__attribute__((weak))
+int thrd_create(thrd_t *__thr, thrd_start_t __func, void *__arg)
+{
+    (void) __thr;
+    (void) __func;
+    (void) __arg;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int thrd_equal(thrd_t __lhs, thrd_t __rhs)
+{
+    (void) __lhs;
+    (void) __rhs;
+
+    return 0;
+}
+
+__attribute__((weak))
+thrd_t thrd_current(void)
+{
+    return (thrd_t)-1;
+}
+
+__attribute__((weak))
+int thrd_sleep(const struct timespec *__time_point,
+		       struct timespec *__remaining)
+{
+    (void) __time_point;
+    (void) __remaining;
+
+    return -1;
+}
+
+__attribute__ ((__noreturn__))
+__attribute__((weak))
+void thrd_exit(int __res)
+{
+    (void) __res;
+
+    do {
+    } while(1);
+}
+
+__attribute__((weak))
+int thrd_detach (thrd_t __thr)
+{
+    (void) __thr;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int thrd_join(thrd_t __thr, int *__res)
+{
+    (void) __thr;
+    (void) __res;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+void thrd_yield(void)
+{
+}
+
+__attribute__((weak))
+int mtx_init (mtx_t *__mutex, int __type)
+{
+    (void) __mutex;
+    (void) __type;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int mtx_lock (mtx_t *__mutex)
+{
+    (void) __mutex;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int mtx_timedlock (mtx_t *__restrict __mutex,
+			  const struct timespec *__restrict __time_point)
+{
+    (void) __mutex;
+    (void) __time_point;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int mtx_trylock (mtx_t *__mutex)
+{
+    (void) __mutex;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int mtx_unlock (mtx_t *__mutex)
+{
+    (void) __mutex;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+void mtx_destroy (mtx_t *__mutex)
+{
+    (void) __mutex;
+}
+
+__attribute__((weak))
+void call_once(once_flag *__flag, void (*__func)(void))
+{
+    (void) __flag;
+    (void) __func;
+}
+
+__attribute__((weak))
+int cnd_init (cnd_t *__cond)
+{
+    (void) __cond;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int cnd_signal (cnd_t *__cond)
+{
+    (void) __cond;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int cnd_broadcast (cnd_t *__cond)
+{
+    (void) __cond;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int cnd_wait (cnd_t *__cond, mtx_t *__mutex)
+{
+    (void) __cond;
+    (void) __mutex;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+int cnd_timedwait (cnd_t *__restrict __cond,
+			  mtx_t *__restrict __mutex,
+			  const struct timespec *__restrict __time_point)
+{
+    (void) __cond;
+    (void) __mutex;
+    (void) __time_point;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+void cnd_destroy (cnd_t *__COND)
+{
+    (void) __COND;
+}
+
+
+/* Thread specific storage functions.  */
+
+__attribute__((weak))
+int tss_create (tss_t *__tss_id, tss_dtor_t __destructor)
+{
+    (void) __tss_id;
+    (void) __destructor;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+void *tss_get (tss_t __tss_id)
+{
+    (void) __tss_id;
+
+    return NULL;
+}
+
+__attribute__((weak))
+int tss_set (tss_t __tss_id, void *__val)
+{
+    (void) __tss_id;
+    (void) __val;
+
+    return thrd_error;
+}
+
+__attribute__((weak))
+void tss_delete (tss_t __tss_id)
+{
+    (void) __tss_id;
+}
+
+#endif /* SUPPORTS_WEAK */