From 1a19f9877ad1d582ac80f8e765eff879e00222ea Mon Sep 17 00:00:00 2001
From: Josh Stone <cuviper@gmail.com>
Date: Wed, 28 Oct 2015 16:05:51 -0700
Subject: [PATCH] Comment how the significand limits lossless int->float
 conversion

---
 src/libcore/num/mod.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 38ad19c3cbe13..a79bdd5961e96 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -1515,6 +1515,10 @@ impl_from! { u16, i32 }
 impl_from! { u16, i64 }
 impl_from! { u32, i64 }
 
+// Note: integers can only be represented with full precision in a float if
+// they fit in the significand, which is 24 bits in f32 and 53 bits in f64.
+// Lossy float conversions are not implemented at this time.
+
 // Signed -> Float
 impl_from! { i8, f32 }
 impl_from! { i8, f64 }