[C11] Claim conformance to WG14 N1482

This paper added a pile of macros for atomic initialization which we
started supporting in Clang 4.0.

Author: AaronBallman

clang/test/C/C11/n1482.c

@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -verify -ffreestanding -std=c11 %s
+// expected-no-diagnostics
+
+/* WG14 N1482: Clang 4
+ * Explicit initializers for atomics
+ *
+ * NB: We can only test the compile time behavior from the paper, not the
+ * runtime behavior.
+ */
+
+#include <stdatomic.h>
+
+#ifndef ATOMIC_BOOL_LOCK_FREE
+#error "Missing ATOMIC_BOOL_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_CHAR_LOCK_FREE
+#error "Missing ATOMIC_CHAR_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_CHAR16_T_LOCK_FREE
+#error "Missing ATOMIC_CHAR16_T_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_CHAR32_T_LOCK_FREE
+#error "Missing ATOMIC_CHAR32_T_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_WCHAR_T_LOCK_FREE
+#error "Missing ATOMIC_WCHAR_T_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_SHORT_LOCK_FREE
+#error "Missing ATOMIC_SHORT_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_INT_LOCK_FREE
+#error "Missing ATOMIC_INT_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_LONG_LOCK_FREE
+#error "Missing ATOMIC_LONG_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_LLONG_LOCK_FREE
+#error "Missing ATOMIC_LLONG_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_POINTER_LOCK_FREE
+#error "Missing ATOMIC_POINTER_LOCK_FREE"
+#endif
+
+#ifndef ATOMIC_VAR_INIT
+#error "Missing ATOMIC_VAR_INIT"
+#endif
+
+#ifndef atomic_init
+#error "Missing atomic_init"
+#endif

clang/www/c_status.html

@@ -548,7 +548,7 @@ <h2 id="c11">C11 implementation status</h2>
     <tr>
       <td>Explicit initializers for atomics</td>
       <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1482.htm">N1482</a></td>
-      <td class="unknown" align="center">Unknown</td>
+      <td class="full" align="center">Clang 4</td>
     </tr>
     <tr>
       <td>Atomics proposal (minus ternary op)</td>