String#sub: fix incorrect behaviour with multibyte string. Fixes #3258

crystal-lang · Sep 5, 2016 · 8bd15bc · 8bd15bc
1 parent fa22a8d
commit 8bd15bc
Showing 2 changed files with 5 additions and 1 deletion.
diff --git a/spec/std/string_spec.cr b/spec/std/string_spec.cr
@@ -845,6 +845,10 @@ describe "String" do
       "fここ bここr bここここz".sub("ここ", "そこ").should eq("fそこ bここr bここここz")
     end
 
+    it "subs with string and string (#3258)" do
+      "私は日本人です".sub("日本", "スペイン").should eq("私はスペイン人です")
+    end
+
     it "subs with string and block" do
       result = "foo boo".sub("oo") { |value|
         value.should eq("oo")

diff --git a/src/string.cr b/src/string.cr
@@ -1366,7 +1366,7 @@ class String
   # "hello yellow".sub("ll") { "dd" } # => "heddo yellow"
   # ```
   def sub(string : String, &block)
-    index = self.index(string)
+    index = self.byte_index(string)
     return self unless index
 
     String.build(bytesize) do |buffer|