factor: add platform sanity check

* src/factor.c: Check against theoretical platform.

diff --git a/src/factor.c b/src/factor.c
index 95383556a55832ad8479c2fbe48673d64d34417e..cb0df9e0962d0edd9c25128a3dcf8d08b6a23058 100644 (file)
--- a/src/factor.c
+++ b/src/factor.c
@@ -134,6 +134,12 @@ typedef intmax_t wide_int;
 #endif
 #define WIDE_UINT_MAX ((wide_uint) -1)
 
+/* Check that we are not on a theoretical (but allowed by
+   POSIX) platform where WIDE_UINT_MAX <= INT_MAX.
+   This could result in undefined behavior due to signed integer
+   overflow if a word promotes to int.  */
+static_assert (INT_MAX < WIDE_UINT_MAX);
+
 #ifndef USE_LONGLONG_H
 /* With the way we use longlong.h, it's only safe to use
    when UWtype = UHWtype, as there were various cases