Fix zero-length array concatenation validation (#45383)

(cherry picked from commit 0a55a8e)

base/abstractarray.jl

@@ -2478,7 +2478,7 @@ function _typed_hvncat_shape(::Type{T}, shape::NTuple{N, Tuple}, row_first, as::
  shapelength == lengthas || throw(ArgumentError("number of elements does not match shape; expected $(shapelength), got $lengthas)"))
  # discover dimensions
  nd = max(N, cat_ndims(as[1]))
- outdims = zeros(Int, nd)
+ outdims = fill(-1, nd)
  currentdims = zeros(Int, nd)
  blockcounts = zeros(Int, nd)
  shapepos = ones(Int, nd)
@@ -2503,7 +2503,7 @@ function _typed_hvncat_shape(::Type{T}, shape::NTuple{N, Tuple}, row_first, as::
 
  isendblock = blockcounts[d] == shapev[d][shapepos[d]]
  if isendblock
- if outdims[d] == 0
+ if outdims[d] == -1
  outdims[d] = currentdims[d]
  elseif outdims[d] != currentdims[d]
  throw(ArgumentError("argument $i has a mismatched number of elements along axis $ad; \

test/abstractarray.jl

@@ -1465,9 +1465,7 @@ using Base: typed_hvncat
  v1 = zeros(Int, 0, 0, 0)
  for v2 ∈ (1, [1])
  for v3 ∈ (2, [2])
- # current behavior, not potentially dangerous.
- # should throw error like above loop
- @test [v1 ;;; v2 v3] == [v2 v3;;;]
+ @test_throws ArgumentError [v1 ;;; v2 v3]
  @test_throws ArgumentError [v1 ;;; v2]
  @test_throws ArgumentError [v1 v1 ;;; v2 v3]
  end