FIXED: #1511 Failure to normalize bigint to tagged int on Windows.

This happened when using GMP for integers that do not fit in a long
but do fit in a tagged integer.

Author: JanWielemaker

src/pl-gmp.c

@@ -1382,14 +1382,18 @@ put_mpz(DECL_LD Word at, mpz_t mpz)
 		   mpz_get_str(buf, 10, mpz));
 	});
 
-#if SIZEOF_LONG < SIZEOF_WORD
-  if ( mpz_cmp(mpz, MPZ_MIN_LONG) >= 0 &&
-       mpz_cmp(mpz, MPZ_MAX_LONG) <= 0 )
-#else
   if ( mpz_cmp(mpz, MPZ_MIN_TAGGED) >= 0 &&
        mpz_cmp(mpz, MPZ_MAX_TAGGED) <= 0 )
+  { int64_t v;
+
+#if SIZEOF_LONG < SIZEOF_WORD
+    bool rc = mpz_to_int64(mpz, &v);
+    assert(rc);
+    (void)rc;
+#else
+    static_assertion(sizeof(word) == sizeof(long));
+    v = mpz_get_si(mpz);
 #endif
-  { long v = mpz_get_si(mpz);
 
     if ( !ensureGlobalSpace(0, ALLOW_GC) )
       return false;

tests/core/test_arith.pl

@@ -1,9 +1,9 @@
 /*  Part of SWI-Prolog
 
     Author:        Jan Wielemaker
-    E-mail:        J.Wielemaker@vu.nl
-    WWW:           http://www.swi-prolog.org
-    Copyright (C): 1985-2024, University of Amsterdam
+    E-mail:        jan@swi-prolog.org
+    WWW:           https://www.swi-prolog.org
+    Copyright (C): 1985-2026, University of Amsterdam
 			      VU University Amsterdam
 			      CWI, Amsterdam
 			      SWI-Prolog Solutions b.v.
@@ -58,7 +58,8 @@
 		    float_compare,
 		    arith_misc,
 		    max_integer_size,
-		    moded_int
+		    moded_int,
+		    canonical_bignum
 		  ]).
 
 :- begin_tests(arith_basics).
@@ -946,6 +947,15 @@
 
 :- end_tests(moded_int).
 
+:- begin_tests(canonical_bignum).
+
+test(to_tagged, MantissaBits == 2251799813685249 ) :-
+    Bits = 0x7ff8000000000001,
+    MantissaWidth = 52,
+    MantissaBits is Bits /\ ((1 << MantissaWidth) - 1).
+
+:- end_tests(canonical_bignum).
+
 :- begin_tests(arith_misc).
 
 test(string) :-