reflect: add test for passing float32 signaling NaNs

Update #40724

Change-Id: I110cdb7c4a2c5db6b85ca951143430555261abf3
Reviewed-on: https://go-review.googlesource.com/c/go/+/348017
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/reflect/abi_test.go

@@ -9,6 +9,7 @@ package reflect_test
 
 import (
 	"internal/abi"
+	"math"
 	"math/rand"
 	"reflect"
 	"runtime"
@@ -962,3 +963,27 @@ func genValue(t *testing.T, typ reflect.Type, r *rand.Rand) reflect.Value {
 	}
 	return v
 }
+
+func TestSignalingNaNArgument(t *testing.T) {
+	v := reflect.ValueOf(func(x float32) {
+		// make sure x is a signaling NaN.
+		u := math.Float32bits(x)
+		if u != snan {
+			t.Fatalf("signaling NaN not correct: %x\n", u)
+		}
+	})
+	v.Call([]reflect.Value{reflect.ValueOf(math.Float32frombits(snan))})
+}
+
+func TestSignalingNaNReturn(t *testing.T) {
+	v := reflect.ValueOf(func() float32 {
+		return math.Float32frombits(snan)
+	})
+	var x float32
+	reflect.ValueOf(&x).Elem().Set(v.Call(nil)[0])
+	// make sure x is a signaling NaN.
+	u := math.Float32bits(x)
+	if u != snan {
+		t.Fatalf("signaling NaN not correct: %x\n", u)
+	}
+}

src/reflect/all_test.go

@@ -4428,8 +4428,9 @@ func TestConvertPanic(t *testing.T) {
 
 var gFloat32 float32
 
+const snan uint32 = 0x7f800001
+
 func TestConvertNaNs(t *testing.T) {
-	const snan uint32 = 0x7f800001
 	type myFloat32 float32
 	x := V(myFloat32(math.Float32frombits(snan)))
 	y := x.Convert(TypeOf(float32(0)))