Fixed #4318: Array.each_product fails on empty arrays

crystal-lang · Apr 20, 2017 · 0f65ea4 · 0f65ea4
1 parent 7b43477
commit 0f65ea4
Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/spec/std/array_spec.cr b/spec/std/array_spec.cr
@@ -1785,6 +1785,14 @@ describe "Array" do
   end
 
   describe "Array.each_product" do
+    it "one empty array" do
+      empty = [] of Int32
+      res = [] of Array(Int32)
+      Array.each_product([empty, [1, 2, 3]]) { |r| res << r }
+      Array.each_product([[1, 2, 3], empty]) { |r| res << r }
+      res.size.should eq(0)
+    end
+
     it "single array" do
       res = [] of Array(Int32)
       Array.each_product([[1]]) { |r| res << r }

diff --git a/src/array.cr b/src/array.cr
@@ -1178,10 +1178,11 @@ class Array(T)
   end
 
   def self.each_product(arrays : Array(Array), reuse = false)
-    pool = arrays.map &.first
     lens = arrays.map &.size
     return if lens.any? &.==(0)
 
+    pool = arrays.map &.first
+
     n = arrays.size
     indices = Array.new(n, 0)