compiling, crashing when run

unittests/testcfg/rtems/include/cmath

@@ -0,0 +1,39 @@
+#pragma once
+
+#include_next <cmath>
+
+extern "C++"
+{
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+
+#undef lround
+#undef erfc
+#undef round
+
+
+using ::lround;
+
+long
+  lround(float __x);
+
+  constexpr long
+  lround(long double __x);
+
+using ::erfc;
+  
+constexpr float
+  erfc(float __x);
+
+  constexpr long double
+  erfc(long double __x);
+  
+  constexpr float
+  round(float __x);
+
+  using ::round;
+  
+  constexpr long double
+  round(long double __x);
+}
+}