Attach filter's docstring to the AbstractArray filter fallback (r…

…ather than an Iterators.filter method not pulled into Base). (#19057)

base/array.jl

@@ -1637,7 +1637,25 @@ end
 
 ## Filter ##
 
-# given a function returning a boolean and an array, return matching elements
+"""
+    filter(function, collection)
+
+Return a copy of `collection`, removing elements for which `function` is `false`. For
+associative collections, the function is passed two arguments (key and value).
+
+```jldocttest
+julia> a = 1:10
+1:10
+
+julia> filter(isodd, a)
+5-element Array{Int64,1}:
+ 1
+ 3
+ 5
+ 7
+ 9
+```
+"""
 filter(f, As::AbstractArray) = As[map(f, As)::AbstractArray{Bool}]
 
 function filter!(f, a::Vector)

base/iterators.jl

@@ -176,25 +176,6 @@ immutable Filter{F,I}
     itr::I
 end
 
-"""
-    filter(function, collection)
-
-Return a copy of `collection`, removing elements for which `function` is `false`. For
-associative collections, the function is passed two arguments (key and value).
-
-```jldocttest
-julia> a = 1:10
-1:10
-
-julia> filter(isodd, a)
-5-element Array{Int64,1}:
- 1
- 3
- 5
- 7
- 9
-```
-"""
 filter(flt, itr) = Filter(flt, itr)
 
 start(f::Filter) = start_filter(f.flt, f.itr)