From 4fc5c90853290fc358c9d5113d2a5b1758e40e30 Mon Sep 17 00:00:00 2001
From: Markus Heikkinen <ittevien@gmail.com>
Date: Thu, 15 Mar 2018 18:32:08 +0200
Subject: [PATCH] Msvc needs /O1 (which implies /Os) to generate smallest
 binaries

---
 src/lib.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 9ec2309..7fa768e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1054,8 +1054,8 @@ impl Build {
                 cmd.args.push(crt_flag.into());
 
                 match &opt_level[..] {
-                    "z" | "s" => cmd.args.push("/Os".into()),
-                    "1" => cmd.args.push("/O1".into()),
+                    // Msvc uses /O1 to enable all optimizations that minimize code size.
+                    "z" | "s" | "1" => cmd.args.push("/O1".into()),
                     // -O3 is a valid value for gcc and clang compilers, but not msvc. Cap to /O2.
                     "2" | "3" => cmd.args.push("/O2".into()),
                     _ => {}