Fix behavior of foldr on single-element arrays (JuliaLang#21497)

Fixes JuliaLang#21493
tekverkp · Apr 23, 2017 · 5955d79 · 5955d79
1 parent 459797d
commit 5955d79
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Showing 2 changed files with 2 additions and 1 deletion.
diff --git a/base/reduce.jl b/base/reduce.jl
@@ -104,7 +104,7 @@ foldl(op, itr) = mapfoldl(identity, op, itr)
 function mapfoldr_impl(f, op, v0, itr, i::Integer)
  # Unroll the while loop once; if v0 is known, the call to op may
  # be evaluated at compile time
- if isempty(itr)
+ if isempty(itr) || i == 0
  return r_promote(op, v0)
  else
  x = itr[i]

diff --git a/test/reduce.jl b/test/reduce.jl
@@ -22,6 +22,7 @@
 @test foldr(+, Int16[]) === Int32(0)
 @test foldr(-, 1:5) == 3
 @test foldr(-, 10, 1:5) == -7
+@test foldr(+, [1]) == 1 # Issue #21493
 
 @test Base.mapfoldr(abs2, -, 2:5) == -14
 @test Base.mapfoldr(abs2, -, 10, 2:5) == -4