Reverts this commit in the cln repo:

commit 2f7994014542920ad6ca726fbd8d023a5f49abc2
Author: Richard Kreckel <kreckel@ginac.de>
Date:   Sun Oct 27 14:57:36 2019 +0100

    Replace typedef int[<negative>] trick with static_assert.

diff -u -r ../src/m4/floatparam.m4 ./m4/floatparam.m4
--- ../src/m4/floatparam.m4	2019-10-27 14:41:55.000000000 +0100
+++ ./m4/floatparam.m4	2019-11-28 08:21:28.161830204 +0100
@@ -22,16 +22,20 @@
         epsilon_bits=-1; y="($type)1.0"
         while true; do
           AC_TRY_COMPILE([],
-            [static_assert((($type)(($type)1.0 + ($type)($y)) == ($type)1.0)
-                         || ($type)(($type)(($type)1.0 + ($type)($y)) - ($type)1.0) != ($type)($y), "");],
+            [typedef int verify[2*(
+               (($type)(($type)1.0 + ($type)($y)) == ($type)1.0)
+               || ($type)(($type)(($type)1.0 + ($type)($y)) - ($type)1.0) != ($type)($y)
+             ) - 1];],
             [break;])
           epsilon_bits=`expr $epsilon_bits + 1`; y="$y * ($type)0.5"
         done
         negepsilon_bits=-1; y="($type)-1.0"
         while true; do
           AC_TRY_COMPILE([],
-            [static_assert((($type)(($type)1.0 + ($type)($y)) == ($type)1.0)
-                         || ($type)(($type)(($type)1.0 + ($type)($y)) - ($type)1.0) != ($type)($y), "");],
+            [typedef int verify[2*(
+               (($type)(($type)1.0 + ($type)($y)) == ($type)1.0)
+               || ($type)(($type)(($type)1.0 + ($type)($y)) - ($type)1.0) != ($type)($y)
+             ) - 1];],
             [break;])
           negepsilon_bits=`expr $negepsilon_bits + 1`; y="$y * ($type)0.5"
         done
@@ -64,22 +68,30 @@
         rounds=
         if test -z "$rounds"; then
           AC_TRY_COMPILE([],
-            [static_assert($ys1 == $y1 && $ys2 == $y2 && $zs1 == $z1 && $zs2 == $z2, "");],
+            [typedef int verify[2*(
+               $ys1 == $y1 && $ys2 == $y2 && $zs1 == $z1 && $zs2 == $z2
+             ) - 1];],
             [rounds=rounds_to_nearest])
         fi
         if test -z "$rounds"; then
           AC_TRY_COMPILE([],
-            [static_assert($ys1 == $y1 && $ys2 == $y1 && $zs1 == $z1 && $zs2 == $z1, "");],
+            [typedef int verify[2*(
+               $ys1 == $y1 && $ys2 == $y1 && $zs1 == $z1 && $zs2 == $z1
+             ) - 1];],
             [rounds=rounds_to_zero])
         fi
         if test -z "$rounds"; then
           AC_TRY_COMPILE([],
-            [static_assert($ys1 == $y2 && $ys2 == $y2 && $zs1 == $z1 && $zs2 == $z1, "");],
+            [typedef int verify[2*(
+               $ys1 == $y2 && $ys2 == $y2 && $zs1 == $z1 && $zs2 == $z1
+             ) - 1];],
             [rounds=rounds_to_infinity])
         fi
         if test -z "$rounds"; then
           AC_TRY_COMPILE([],
-            [static_assert($ys1 == $y1 && $ys2 == $y1 && $zs1 == $z2 && $zs2 == $z2, "");],
+            [typedef int verify[2*(
+               $ys1 == $y1 && $ys2 == $y1 && $zs1 == $z2 && $zs2 == $z2
+             ) - 1];],
             [rounds=rounds_to_minus_infinity])
         fi
         if test -n "$rounds"; then
diff -u -r ../src/m4/intparam.m4 ./m4/intparam.m4
--- ../src/m4/intparam.m4	2019-11-02 17:04:20.000000000 +0100
+++ ./m4/intparam.m4	2019-11-28 08:21:28.161830204 +0100
@@ -113,7 +113,7 @@
         echo "#error \"Integer types long long and unsigned long long have different sizes!!\""
       fi
     fi
-    AC_TRY_COMPILE([], [static_assert(sizeof(char*) <= sizeof(intptr_t), "");],
+    AC_TRY_COMPILE([], [typedef int verify[2*(sizeof(char*)<=sizeof (long))-1];],
       [], [echo "#error \"Type char * does not fit into an intptr_t!!\""])
     _AC_COMPUTE_INT([sizeof (char *)], [pointer_size])
     pointer_bitsize=`expr $pointer_size '*' $char_bitsize`
@@ -258,7 +258,7 @@
 [
   n=1; x="($1)2"
   while true; do
-    AC_TRY_COMPILE([], [static_assert(($1)($x) == 0, "");],
+    AC_TRY_COMPILE([], [typedef int verify[2*(($1)($x) == 0) - 1];],
       [$2=$n; break;],
       [if test $n = 1000; then $2=; break; fi;])
     n=`expr $n + 1`; x="$x * ($1)2"
@@ -290,7 +290,7 @@
 #else
 # define alignof(type)  offsetof (struct { char slot1; type slot2; }, slot2)
 #endif
-], [static_assert(alignof($1) == $n, "");],
+], [typedef int verify[2*(alignof($1) == $n) - 1];],
       [$2=$n; break;]
       [if test $n = 0; then $2=; break; fi])
     n=`expr $n '*' 2`
--- ../src/include/cln/number.h	2019-10-27 14:29:45.000000000 +0100
+++ ./include/cln/number.h	2019-11-28 08:21:28.161830204 +0100
@@ -257,8 +257,7 @@
 inline const type& the(const cl_number& x)
 {
 	// check that sizeof(type)==sizeof(cl_number)
-	static_assert(sizeof(type)==sizeof(cl_number),
-	              "sizeof(type)!=sizeof(cl_number)");
+	int (*dummy1)(int assertion1 [1 - 2 * (sizeof(type) != sizeof(cl_number))]); (void)dummy1;
 	return *(const type *) &x;
 }
 // Conversions to subtypes without checking, macro version: