Implement LWG 2835 - fix <tgmath.h>

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324923 91177308-0d34-0410-b5e6-96231b3b80d8

include/tgmath.h

@@ -14,16 +14,24 @@
 /*
     tgmath.h synopsis
 
-#include <complex.h>
-#include <math.h>
+#include <ctgmath>
 
 */
 
-#include <complex.h>
-#include <math.h>
+#include <__config>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
+#ifdef __cplusplus
+
+#include <ctgmath>
+
+#else  // __cplusplus
+
+#include_next <tgmath.h>
+
+#endif  // __cplusplus
+
 #endif  // _LIBCPP_TGMATH_H

www/cxx1z_status.html

@@ -467,7 +467,7 @@
 	<tr><td><a href="https://wg21.link/LWG2824">2824</a></td><td>list::sort should say that the order of elements is unspecified if an exception is thrown</td><td>Kona</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2826">2826</a></td><td>string_view iterators use old wording</td><td>Kona</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2834">2834</a></td><td>Resolution LWG 2223 is missing wording about end iterators</td><td>Kona</td><td>Complete</td></tr>
-	<tr><td><a href="https://wg21.link/LWG2835">2835</a></td><td>LWG 2536 seems to misspecify &lt;tgmath.h&gt;</td><td>Kona</td><td></td></tr>
+	<tr><td><a href="https://wg21.link/LWG2835">2835</a></td><td>LWG 2536 seems to misspecify &lt;tgmath.h&gt;</td><td>Kona</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2837">2837</a></td><td>gcd and lcm should support a wider range of input values</td><td>Kona</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2838">2838</a></td><td>is_literal_type specification needs a little cleanup</td><td>Kona</td><td>Complete</td></tr>
 	<tr><td><a href="https://wg21.link/LWG2842">2842</a></td><td>in_place_t check for optional::optional(U&amp;&amp;) should decay U</td><td>Kona</td><td>Complete</td></tr>