Fix findmax and findmin with iterables

The state is not guaranteed to be equivalent to the index
of the element.

(cherry picked from commit bbaaf54)
ref #14086

Author: nalimilan

base/abstractarray.jl

@@ -408,9 +408,6 @@ start(A::AbstractArray) = (@_inline_meta(); itr = eachindex(A); (itr, start(itr)
 next(A::AbstractArray,i) = (@_inline_meta(); (idx, s) = next(i[1], i[2]); (A[idx], (i[1], s)))
 done(A::AbstractArray,i) = done(i[1], i[2])
 
-iterstate(i) = i
-iterstate(i::Tuple{UnitRange{Int},Int}) = i[2]
-
 # eachindex iterates over all indices. LinearSlow definitions are later.
 eachindex(A::AbstractArray) = (@_inline_meta(); eachindex(linearindexing(A), A))
 

base/array.jl

@@ -830,36 +830,36 @@ function findmax(a)
     if isempty(a)
         throw(ArgumentError("collection must be non-empty"))
     end
-    i = start(a)
-    mi = i
-    m, i = next(a, i)
-    while !done(a, i)
-        iold = i
-        ai, i = next(a, i)
+    s = start(a)
+    mi = i = 1
+    m, s = next(a, s)
+    while !done(a, s)
+        ai, s = next(a, s)
+        i += 1
         if ai > m || m!=m
             m = ai
-            mi = iold
+            mi = i
         end
     end
-    return (m, iterstate(mi))
+    return (m, mi)
 end
 
 function findmin(a)
     if isempty(a)
         throw(ArgumentError("collection must be non-empty"))
     end
-    i = start(a)
-    mi = i
-    m, i = next(a, i)
-    while !done(a, i)
-        iold = i
-        ai, i = next(a, i)
+    s = start(a)
+    mi = i = 1
+    m, s = next(a, s)
+    while !done(a, s)
+        ai, s = next(a, s)
+        i += 1
         if ai < m || m!=m
             m = ai
-            mi = iold
+            mi = i
         end
     end
-    return (m, iterstate(mi))
+    return (m, mi)
 end
 
 indmax(a) = findmax(a)[2]

base/multidimensional.jl

@@ -3,7 +3,7 @@
 ### Multidimensional iterators
 module IteratorsMD
 
-import Base: eltype, length, start, done, next, last, getindex, setindex!, linearindexing, min, max, eachindex, ndims, iterstate
+import Base: eltype, length, start, done, next, last, getindex, setindex!, linearindexing, min, max, eachindex, ndims
 importall ..Base.Operators
 import Base: simd_outer_range, simd_inner_length, simd_index, @generated
 import Base: @nref, @ncall, @nif, @nexprs, LinearFast, LinearSlow, to_index
@@ -59,8 +59,6 @@ immutable CartesianRange{I<:CartesianIndex}
     stop::I
 end
 
-iterstate{CR<:CartesianRange,CI<:CartesianIndex}(i::Tuple{CR,CI}) = Base._sub2ind(i[1].stop.I, i[2].I)
-
 @generated function CartesianRange{N}(I::CartesianIndex{N})
     startargs = fill(1, N)
     :(CartesianRange($I($(startargs...)), I))

test/arrayops.jl

@@ -306,7 +306,7 @@ for i = 1:3
 end
 @test isequal(a,findn(z))
 
-#argmin argmax
+#findmin findmax indmin indmax
 @test indmax([10,12,9,11]) == 2
 @test indmin([10,12,9,11]) == 3
 @test findmin([NaN,3.2,1.8]) == (1.8,3)
@@ -316,6 +316,16 @@ end
 @test findmin([3.2,1.8,NaN,2.0]) == (1.8,2)
 @test findmax([3.2,1.8,NaN,2.0]) == (3.2,1)
 
+# #14085
+@test findmax(4:9) == (9,6)
+@test indmax(4:9) == 6
+@test findmin(4:9) == (4,1)
+@test indmin(4:9) == 1
+@test findmax(5:-2:1) == (5,1)
+@test indmax(5:-2:1) == 1
+@test findmin(5:-2:1) == (1,3)
+@test indmin(5:-2:1) == 3
+
 ## permutedims ##
 
 #keeps the num of dim