From 201d38d6fe1a8be5aa5237807103f49b4c8cb53c Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Fri, 25 Oct 2024 23:10:23 +0200
Subject: [PATCH]   * fix fpc_frac_real to properly thrown an exception on
 +/-Inf/NaN

---
 rtl/inc/genmath.inc | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/rtl/inc/genmath.inc b/rtl/inc/genmath.inc
index d4d41f722e..6637ded744 100644
--- a/rtl/inc/genmath.inc
+++ b/rtl/inc/genmath.inc
@@ -1757,15 +1757,24 @@ end;
 
 
 {$ifndef FPC_SYSTEM_HAS_FRAC}
+{$push}
+{ if we have to check manually fpu exceptions, then force the result assignment statement here to
+  throw one }
+{$CHECKFPUEXCEPTIONS+}
+{ turn off fastmath as it converts (d-d)/zero into 0 and thus not raising an exception }
+{$OPTIMIZATION NOFASTMATH}
 function fpc_frac_real(d : ValReal) : ValReal;compilerproc;
+  const
+    zero: ValReal = 0.0;
   begin
     { Nan or +/-Inf }
     if (float64high(d) and $7ff00000)=$7ff00000 then
       { return NaN }
-      result := (d-d)/0.0 
+      result := zero/zero
     else
       result := d - Int(d);
   end;
+{$pop}
 {$endif}