ICU-10271 when #include <atomic> doesn't work, don't use it (autoconf mode only)

X-SVN-Rev: 33978

diff --git a/icu4c/source/common/putilimp.h b/icu4c/source/common/putilimp.h
index fc6788e4877af0f19234b708b8c5f2460ee9f000..1ea9fc92150bb25619d20f716e7263a4c69af75e 100644 (file)
--- a/icu4c/source/common/putilimp.h
+++ b/icu4c/source/common/putilimp.h
@@ -197,7 +197,6 @@ typedef size_t uintptr_t;
 
 /** @} */
 
-
 /**
  * \def U_HAVE_STD_ATOMICS
  * Defines whether the standard C++11 <atomic> is available.
@@ -213,8 +212,16 @@ typedef size_t uintptr_t;
 #elif __clang__ && __clang_major__==3 && __clang_minor__<=1
     /* Clang 3.1. Atomics not fully implemented. */
 #   define U_HAVE_STD_ATOMICS 0
-#else 
-#   define U_HAVE_STD_ATOMICS 1
+#else
+#   if defined(U_HAVE_ATOMIC) /* autoconf detected or manually set */
+#       if U_HAVE_ATOMIC
+#          define U_HAVE_STD_ATOMICS 1 /* #include <atomic> works */
+#       else
+#          define U_HAVE_STD_ATOMICS 0 /* #include <atomic> doesn't work. */
+#       endif
+#   else
+#       define U_HAVE_STD_ATOMICS 0  /* Default: do not use */
+#   endif
 #endif
 
 #else