Patch Float.frexp significant stats where int_of_float is undefined on nan and infinity

Author: jmid

test/core/QCheck2_tests.ml

@@ -1048,7 +1048,8 @@ module Stats = struct
 
   let float_tests = (* Float.frexp nan (and infinity) is undefined and may return a 32766 exponent on Alpine *)
     let float_expon_dist  = ("exponent",    fun f -> if Float.(is_nan f || is_infinite f) then 0 else snd (Float.frexp f)) in
-    let float_signif_dist = ("significant", fun f -> let s = fst (Float.frexp f) in int_of_float (s *. 1000000.)) in
+    let float_signif_dist = ("significant", fun f -> if Float.(is_nan f || is_infinite f) (* int_of_float is undefined on nan and infinity *)
+                                                     then 0 else let s = fst (Float.frexp f) in int_of_float (s *. 1000000.)) in
     let float_fpclass f = match Float.classify_float f with
       | FP_normal    -> "FP_normal"
       | FP_subnormal -> "FP_subnormal"

test/core/QCheck_tests.ml

@@ -1111,9 +1111,10 @@ module Stats = struct
       Test.make ~name:"exponential -10. dist" ~count:5_000 (add_stat float_dist (exponential (-10.))) (fun _ -> true);
     ]
 
-  let float_tests =
+  let float_tests = (* Float.frexp nan (and infinity) is undefined and may return a 32766 exponent on Alpine *)
     let float_expon_dist  = ("exponent",    fun f -> if Float.(is_nan f || is_infinite f) then 0 else snd (Float.frexp f)) in
-    let float_signif_dist = ("significant", fun f -> let s = fst (Float.frexp f) in int_of_float (s *. 1000000.)) in
+    let float_signif_dist = ("significant", fun f -> if Float.(is_nan f || is_infinite f) (* int_of_float is undefined on nan and infinity *)
+                                                     then 0 else let s = fst (Float.frexp f) in int_of_float (s *. 1000000.)) in
     let float_fpclass f = match Float.classify_float f with
       | FP_normal    -> "FP_normal"
       | FP_subnormal -> "FP_subnormal"