From 0dded87808a2640558e0364f7e46da71ad2f3fac Mon Sep 17 00:00:00 2001
From: Kenta Sato <bicycle1885@gmail.com>
Date: Tue, 12 Mar 2019 04:06:52 +0900
Subject: [PATCH] allow chop to take an empty string (#31312)

(cherry picked from commit 023c8e4b068eff37e8dcafc9fed317f25eb871b8)
---
 base/strings/util.jl | 3 +++
 test/strings/util.jl | 1 +
 2 files changed, 4 insertions(+)

diff --git a/base/strings/util.jl b/base/strings/util.jl
index ad27f9c7f84e6..ff9beab76b9c5 100644
--- a/base/strings/util.jl
+++ b/base/strings/util.jl
@@ -96,6 +96,9 @@ julia> chop(a, head = 5, tail = 5)
 ```
 """
 function chop(s::AbstractString; head::Integer = 0, tail::Integer = 1)
+    if isempty(s)
+        return SubString(s)
+    end
     SubString(s, nextind(s, firstindex(s), head), prevind(s, lastindex(s), tail))
 end
 
diff --git a/test/strings/util.jl b/test/strings/util.jl
index 17d1f9355006c..20de96ee9ce87 100644
--- a/test/strings/util.jl
+++ b/test/strings/util.jl
@@ -301,6 +301,7 @@ end
     @test chomp("foo\r\n") == "foo"
     @test chomp("fo∀\r\n") == "fo∀"
     @test chomp("fo∀") == "fo∀"
+    @test chop("") == ""
     @test chop("fooε") == "foo"
     @test chop("foεo") == "foε"
     @test chop("∃∃∃∃") == "∃∃∃"