-#ifndef PERL_GET_CONTEXT
-# define PERL_GET_CONTEXT PTHREAD_GETSPECIFIC(PL_thr_key)
-#endif
-
-#ifndef PERL_SET_CONTEXT
-# define PERL_SET_CONTEXT(t) \
- STMT_START { \
- int _eC_; \
- if ((_eC_ = pthread_setspecific(PL_thr_key, (void *)(t)))) \
- Perl_croak_nocontext("panic: pthread_setspecific (%d) [%s:%d]", \
- _eC_, __FILE__, __LINE__); \
+#if defined(PERL_THREAD_LOCAL) && !defined(PERL_GET_CONTEXT) && !defined(PERL_SET_CONTEXT) && !defined(__cplusplus)
+/* Use C11 thread-local storage, where possible.
+ * Frustratingly we can't use it for C++ extensions, C++ and C disagree on the
+ * syntax used for thread local storage, meaning that the working token that
+ * Configure probed for C turns out to be a compiler error on C++. Great.
+ * (Well, unless one or both is supporting non-standard syntax as an extension)
+ * As Configure doesn't have a way to probe for C++ dialects, we just take the
+ * safe option and do the same as 5.34.0 and earlier - use pthreads on C++.
+ * Of course, if C++ XS extensions really want to avoid *all* this overhead,
+ * they should #define PERL_NO_GET_CONTEXT and pass aTHX/aTHX_ explicitly) */
+# define PERL_USE_THREAD_LOCAL
+extern PERL_THREAD_LOCAL void *PL_current_context;
+
+# define PERL_GET_CONTEXT PL_current_context
+
+/* We must also call pthread_setspecific() always, as C++ code has to read it
+ * with pthreads (the #else side just below) */
+
+# define PERL_SET_CONTEXT(t) \
+ STMT_START { \
+ int _eC_; \
+ if ((_eC_ = pthread_setspecific(PL_thr_key, \
+ PL_current_context = (void *)(t)))) \
+ Perl_croak_nocontext("panic: pthread_setspecific (%d) [%s:%d]", \
+ _eC_, __FILE__, __LINE__); \