Fix :noshift construction of an empty SubString (JuliaLang#51923)

lazarusA · Dec 30, 2023 · 2091058 · 2091058
1 parent 9deee46
commit 2091058
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/base/strings/substring.jl b/base/strings/substring.jl
@@ -37,7 +37,7 @@ struct SubString{T<:AbstractString} <: AbstractString
  return new(s, i-1, nextind(s,j)-i)
  end
  function SubString{T}(s::T, i::Int, j::Int, ::Val{:noshift}) where T<:AbstractString
- @boundscheck begin
+ @boundscheck if !(i == j == 0)
  si, sj = i + 1, prevind(s, j + i + 1)
  @inbounds isvalid(s, si) || string_index_err(s, si)
  @inbounds isvalid(s, sj) || string_index_err(s, sj)

diff --git a/test/strings/basic.jl b/test/strings/basic.jl
@@ -203,6 +203,12 @@ end
  @test (@views (x[3], x[1:2], x[[1,4]])) isa Tuple{Char, SubString, String}
  @test (@views (x[3], x[1:2], x[[1,4]])) == ('c', "ab", "ad")
  end
+
+ @testset ":noshift constructor" begin
+ @test SubString("", 0, 0, Val(:noshift)) == ""
+ @test SubString("abcd", 0, 1, Val(:noshift)) == "a"
+ @test SubString("abcd", 0, 4, Val(:noshift)) == "abcd"
+ end
 end