nan-boxing: use GCC pragmas to disable aliasing warnings.

* arith.c (flo): The line of code which triggers the
aliasing diagnostic is wrapped with GNU-C-specific
pramgas that disable the diagnostic just for that line.

* lib.h (c_f): Likewise.

* configure: Drop the test which adds -Wno-strict-aliasing
to the DIAG_FLAGS;

1 files changed, 7 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index 35a237fa..c2f42408 100644
--- a/lib.h
+++ b/lib.h
@@ -625,7 +625,14 @@ INLINE double c_f(val num)
 {
 #if CONFIG_NAN_BOXING
   ucnum u = coerce(ucnum, num) - NAN_FLNUM_DELTA;
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+#endif
   return *coerce(double *, &u);
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
 #else
   return num->fl.n;
 #endif