Added ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE macro and has_atomic_always_lock_free trait

Fixed coditional unit tests in test_atomic

Author: John Wellbelove

include/etl/platform.h

@@ -434,6 +434,15 @@ SOFTWARE.
   #else
     #define ETL_HAS_ATOMIC 0
   #endif
+  #if ((ETL_USING_CPP17 && (ETL_USING_STL || defined(ETL_IN_UNIT_TEST))) || \
+        defined(ETL_COMPILER_ARM5)  || \
+        defined(ETL_COMPILER_ARM6)  || \
+        defined(ETL_COMPILER_GCC)   || \
+        defined(ETL_COMPILER_CLANG))
+    #define ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE 1
+  #else
+    #define ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE 0
+  #endif
 #endif
 
 //*************************************
@@ -524,6 +533,7 @@ namespace etl
     static ETL_CONSTANT bool has_8bit_types                   = (ETL_USING_8BIT_TYPES == 1);
     static ETL_CONSTANT bool has_64bit_types                  = (ETL_USING_64BIT_TYPES == 1);
     static ETL_CONSTANT bool has_atomic                       = (ETL_HAS_ATOMIC == 1);
+    static ETL_CONSTANT bool has_atomic_always_lock_free      = (ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE == 1);
     static ETL_CONSTANT bool has_nullptr                      = (ETL_HAS_NULLPTR == 1);
     static ETL_CONSTANT bool has_char8_t                      = (ETL_HAS_CHAR8_T == 1);
     static ETL_CONSTANT bool has_native_char8_t               = (ETL_HAS_NATIVE_CHAR8_T == 1);

test/test_atomic.cpp

@@ -76,10 +76,10 @@ namespace
 
       CHECK_EQUAL(compare.is_lock_free(), test.is_lock_free());
 
-//#if ETL_NOT_USING_STL && ETL_HAS_ATOMIC
-//      CHECK_TRUE(etl::atomic<int>::is_always_lock_free);
-//      CHECK_TRUE(test.is_always_lock_free);
-//#endif
+#if ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE
+      CHECK_TRUE(etl::atomic<int>::is_always_lock_free);
+      CHECK_TRUE(test.is_always_lock_free);
+#endif
     }
 
     //*************************************************************************
@@ -90,28 +90,28 @@ namespace
 
       CHECK_EQUAL(compare.is_lock_free(), test.is_lock_free());
 
-#if ETL_NOT_USING_STL && ETL_HAS_ATOMIC
+#if ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE
       CHECK_TRUE(etl::atomic<int*>::is_always_lock_free);
       CHECK_TRUE(test.is_always_lock_free);
 #endif
     }
 
-//#if ETL_NOT_USING_STL && ETL_HAS_ATOMIC
-//    //*************************************************************************
-//    TEST(test_atomic_is_always_lock_free)
-//    {
-//      struct S 
-//      {
-//        int a;
-//        int b;
-//        int c;
-//      };
-//
-//      CHECK_TRUE(etl::atomic<int>::is_always_lock_free);
-//      CHECK_TRUE(etl::atomic<int*>::is_always_lock_free);
-//      CHECK_FALSE(etl::atomic<S>::is_always_lock_free);
-//    }
-//#endif
+#if ETL_HAS_ATOMIC_ALWAYS_LOCK_FREE
+    //*************************************************************************
+    TEST(test_atomic_is_always_lock_free)
+    {
+      struct S 
+      {
+        int a;
+        int b;
+        int c;
+      };
+
+      CHECK_TRUE(etl::atomic<int>::is_always_lock_free);
+      CHECK_TRUE(etl::atomic<int*>::is_always_lock_free);
+      CHECK_FALSE(etl::atomic<S>::is_always_lock_free);
+    }
+#endif
 
     //*************************************************************************
     TEST(test_atomic_integer_load)