Fix findmax and findmin with iterables

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

Author: nalimilan

base/array.jl

@@ -821,36 +821,38 @@ 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)
+    s = start(a)
+    mi = i = 1
+    m, s = next(a, s)
+    while !done(a, s)
+        i += 1
         iold = i
-        ai, i = next(a, i)
+        ai, s = next(a, s)
         if ai > m || m!=m
             m = ai
             mi = iold
         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)
+    s = start(a)
+    mi = i = 1
+    m, s = next(a, s)
+    while !done(a, s)
+        i += 1
         iold = i
-        ai, i = next(a, i)
+        ai, s = next(a, s)
         if ai < m || m!=m
             m = ai
             mi = iold
         end
     end
-    return (m, iterstate(mi))
+    return (m, mi)
 end
 
 indmax(a) = findmax(a)[2]

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