Tighten validation of hvncat implementation (#43940)

base/abstractarray.jl

@@ -2364,6 +2364,24 @@ function _typed_hvncat_dims(::Type{T}, dims::NTuple{N, Int}, row_first::Bool, as
 
  outdims = zeros(Int, N)
 
+ # validate shapes for lowest level of concatenation
+ d = findfirst(>(1), dims)
+ if d !== nothing # all dims are 1
+ nblocks = length(as) ÷ dims[d]
+ for b ∈ 1:nblocks
+ offset = ((b - 1) * dims[d])
+ startelementi = offset + 1
+ for i ∈ offset .+ (2:dims[d])
+ for dd ∈ 1:N
+ dd == d && continue
+ if size(as[startelementi], dd) != size(as[i], dd)
+ throw(ArgumentError("incompatible shape in element $i"))
+ end
+ end
+ end
+ end
+ end
+
  # discover number of rows or columns
  for i ∈ 1:dims[d1]
  outdims[d1] += cat_size(as[i], d1)

test/abstractarray.jl

@@ -1534,6 +1534,10 @@ using Base: typed_hvncat
  @test Int[] == typed_hvncat(Int, 1) isa Array{Int, 1}
  @test Array{Int, 2}(undef, 0, 0) == typed_hvncat(Int, 2) isa Array{Int, 2}
  @test Array{Int, 3}(undef, 0, 0, 0) == typed_hvncat(Int, 3) isa Array{Int, 3}
+
+ # Issue 43933 - semicolon precedence mistake should produce an error
+ @test_throws ArgumentError [[1 1]; 2 ;; 3 ; [3 4]]
+ @test_throws ArgumentError [[1 ;;; 1]; 2 ;;; 3 ; [3 ;;; 4]]
 end
 
 @testset "keepat!" begin