mention getindex() shouldn't return a "view" (#47099)

fix  #47078

---------

Co-authored-by: Milan Bouchet-Valat <[email protected]>
Co-authored-by: Tim Holy <[email protected]>

Author: 3 people

base/abstractarray.jl

@@ -1256,6 +1256,11 @@ end
 
 Return a subset of array `A` as specified by `inds`, where each `ind` may be,
 for example, an `Int`, an [`AbstractRange`](@ref), or a [`Vector`](@ref).
+
+When `inds` selects multiple elements, this function returns a newly
+allocated array. To index multiple elements without making a copy,
+use [`view`](@ref) instead.
+
 See the manual section on [array indexing](@ref man-array-indexing) for details.
 
 # Examples

doc/src/manual/interfaces.md

@@ -152,10 +152,10 @@ julia> collect(Iterators.reverse(Squares(4)))
 
 | Methods to implement | Brief description                |
 |:-------------------- |:-------------------------------- |
-| `getindex(X, i)`     | `X[i]`, indexed element access   |
-| `setindex!(X, v, i)` | `X[i] = v`, indexed assignment   |
+| `getindex(X, i)`     | `X[i]`, indexed access, non-scalar `i` should allocate a copy  |
+| `setindex!(X, v, i)` | `X[i] = v`, indexed assignment         |
 | `firstindex(X)`         | The first index, used in `X[begin]` |
-| `lastindex(X)`           | The last index, used in `X[end]` |
+| `lastindex(X)`           | The last index, used in `X[end]`   |
 
 For the `Squares` iterable above, we can easily compute the `i`th element of the sequence by squaring
 it.  We can expose this as an indexing expression `S[i]`. To opt into this behavior, `Squares`