From 4cb26d462ee6b76c373d2921dbedd5446eed61b2 Mon Sep 17 00:00:00 2001
From: Daniel Wong <drojfjord@gmail.com>
Date: Wed, 24 Jul 2019 04:21:46 +1000
Subject: [PATCH] Allow disabling all alpha optimizations (#181)

Fixes a bug where oxipng would crash if alpha optimizations were all disabled.
---
 src/reduction/alpha.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/reduction/alpha.rs b/src/reduction/alpha.rs
index b255e9f7..a13a9056 100644
--- a/src/reduction/alpha.rs
+++ b/src/reduction/alpha.rs
@@ -16,7 +16,10 @@ pub(crate) fn try_alpha_reductions(
     alphas: &HashSet<AlphaOptim>,
     eval: &Evaluator,
 ) {
-    assert!(!alphas.is_empty());
+    if alphas.is_empty() {
+        return;
+    }
+
     let alphas = alphas.iter().collect::<Vec<_>>();
     let alphas_iter = alphas.par_iter().with_max_len(1);
     alphas_iter