async_posix.h: remove unreachable OPENSSL_SYS_TANDEM

The top-level #if requires !defined(OPENSSL_SYS_TANDEM):

  #if defined(OPENSSL_SYS_UNIX)                                 \
      && defined(OPENSSL_THREADS) && !defined(OPENSSL_NO_ASYNC) \
      && !defined(__ANDROID__) && !defined(__OpenBSD__)         \
      && !defined(OPENSSL_SYS_TANDEM)

so the nested

  #if defined(OPENSSL_SYS_TANDEM)
  #include <tdmsig.h>
  #else
  #include <ucontext.h>
  #endif

can never select the OPENSSL_SYS_TANDEM condition.

According to discussion on the issue 31074, removal of the second
(unreachable) condition is the way to go.

Fixes #31074

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
MergeDate: Thu May  7 20:11:08 2026
(Merged from https://github.com/openssl/openssl/pull/31076)

diff --git a/crypto/async/async_local.h b/crypto/async/async_local.h
index b41309ac41d8f6a98cdf3d0769dfcec6dec68a1f..e1d1113464640b1114f71b22ef8afb696c399e37 100644 (file)
--- a/crypto/async/async_local.h
+++ b/crypto/async/async_local.h
@@ -94,11 +94,7 @@ VOID CALLBACK async_start_func_win(PVOID unused);
  */
 #define USE_SWAPCONTEXT
 #endif
-#if defined(OPENSSL_SYS_TANDEM)
-#include <tdmsig.h>
-#else
 #include <ucontext.h>
-#endif
 #ifndef USE_SWAPCONTEXT
 #include <setjmp.h>
 #endif