From 304c0e78bcb0af2a3ddf0aa1843bc376f083c12d Mon Sep 17 00:00:00 2001
From: Julien Reichardt <git@jrei.ch>
Date: Tue, 16 Jun 2020 00:18:58 +0200
Subject: [PATCH] Fix slow compile times for big StaticArray

Fixes #2485
---
 src/static_array.cr | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/static_array.cr b/src/static_array.cr
index 646b31da09a0..b8a32eff0070 100644
--- a/src/static_array.cr
+++ b/src/static_array.cr
@@ -62,11 +62,13 @@ struct StaticArray(T, N)
   # ```
   # StaticArray(Int32, 3).new { |i| i * 2 } # => StaticArray[0, 2, 4]
   # ```
-  def self.new(&block : Int32 -> T)
+  def self.new(& : Int32 -> T)
     array = uninitialized self
-    N.times do |i|
-      array.to_unsafe[i] = yield i
-    end
+    buf = array.to_unsafe
+    # Using a macro prevents slow compile times: https://github.com/crystal-lang/crystal/issues/2485
+    {% for i in 0...N %}
+    buf[{{i.id}}] = yield {{i.id}}
+    {% end %}
     array
   end