1 files changed, 25 insertions, 0 deletions
diff --git a/src/runtime/float_test.go b/src/runtime/float_test.go
new file mode 100644
index 0000000..b2aa43d
--- /dev/null
+++ b/src/runtime/float_test.go
@@ -0,0 +1,25 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"testing"
+)
+
+func TestIssue48807(t *testing.T) {
+	for _, i := range []uint64{
+		0x8234508000000001, // from issue48807
+		1<<56 + 1<<32 + 1,
+	} {
+		got := float32(i)
+		dontwant := float32(float64(i))
+		if got == dontwant {
+			// The test cases above should be uint64s such that
+			// this equality doesn't hold. These examples trigger
+			// the case where using an intermediate float64 doesn't work.
+			t.Errorf("direct float32 conversion doesn't work: arg=%x got=%x dontwant=%x", i, got, dontwant)
+		}
+	}
+}