Add NEWS.md; slightly better deprecation message

and a few breadcrumbs to help guide the deprecation removal process

NEWS.md

@@ -279,6 +279,11 @@ Deprecated or removed
   * The keyword `immutable` is fully deprecated to `struct`, and
     `type` is fully deprecated to `mutable struct` ([#19157], [#20418]).
 
+  * Indexing into multidimensional arrays with more than one index but fewer indices than there are
+    dimensions is no longer permitted when those trailing dimensions have lengths greater than 1.
+    Instead, reshape the array or add trailing indices so the dimensionality and number of indices
+    match ([#14770], [#23628]).
+
   * The method `srand(rng, filename, n=4)` has been deprecated ([#21359]).
 
   * The `cholfact`/`cholfact!` methods that accepted an `uplo` symbol have been deprecated

base/deprecated.jl

@@ -1726,7 +1726,9 @@ function countnz(x)
 end
 
 # issue #14470
-# This definition will gracefully supercede the real definition until deprecations are removed
+# TODO: More deprecations must be removed in src/cgutils.cpp:emit_array_nd_index()
+# TODO: Re-enable the disabled tests marked PLI
+# On the Julia side, this definition will gracefully supercede the new behavior (already coded)
 @inline function checkbounds_indices(::Type{Bool}, IA::Tuple{Any,Vararg{Any}}, ::Tuple{})
     any(x->unsafe_length(x)==0, IA) && return false
     any(x->unsafe_length(x)!=1, IA) && return _depwarn_for_trailing_indices(IA)
@@ -1737,7 +1739,7 @@ function _depwarn_for_trailing_indices(n::Integer) # Called by the C boundscheck
     true
 end
 function _depwarn_for_trailing_indices(t::Tuple)
-    depwarn("omitting indices for non-singleton trailing dimensions is deprecated. Add `$(map(first, t))` as trailing indices or use `reshape` to make the dimensionality of the array match the number of indices.", (:getindex, :setindex!, :view))
+    depwarn("omitting indices for non-singleton trailing dimensions is deprecated. Add `$(join(map(first, t),','))` as trailing indices or use `reshape` to make the dimensionality of the array match the number of indices.", (:getindex, :setindex!, :view))
     true
 end