X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/35c0995dde0c37486681630acdd8d26659a4732e..aa02ed367404c659ab7205ef9662ef92032d7786:/math/mpint.h

diff --git a/math/mpint.h b/math/mpint.h
index 7867f6a..f551980 100644
--- a/math/mpint.h
+++ b/math/mpint.h
@@ -42,6 +42,25 @@
 
 /*----- Generic translation macros ----------------------------------------*/
 
+/* --- Warning damage control --- *
+ *
+ * GCC (at least) isn't clever enough to work out that the division in
+ * @MP_FROMINT@ is actually safe (since it will only be executed if @_i >
+ * MPW_MAX@, which would prove that @(type)MPW_MAX + 1 != 0@).  So here's
+ * some machinery to shut it up.
+ */
+
+#if __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+#  define MP_FROMINT_MUFFLE_WARNING(x) do {				\
+	_Pragma("GCC diagnostic push")					\
+	_Pragma("GCC diagnostic ignored \"-Wdiv-by-zero\"")		\
+	x								\
+	_Pragma("GCC diagnostic pop")					\
+   } while (0)
+#else
+#  define MP_FROMINT_MUFFLE_WARNING(x) do { x } while (0)
+#endif
+
 /* --- @MP_FROMINT@ --- *
  *
  * Arguments:	@d@ = destination multiprecision integer
@@ -71,7 +90,7 @@
       if (_i <= MPW_MAX)						\
 	break;								\
       else								\
-	_i /= (type)MPW_MAX + 1;					\
+	MP_FROMINT_MUFFLE_WARNING({ _i /= (type)MPW_MAX + 1; });	\
     }									\
   } else {								\
     _d->f |= MP_NEG;							\
@@ -84,7 +103,7 @@
       if (_i >= -MPW_MAX)						\
 	break;								\
       else								\
-	_i /= (type)MPW_MAX + 1;					\
+	MP_FROMINT_MUFFLE_WARNING({ _i /= (type)MPW_MAX + 1; });	\
     }									\
   }									\
 									\