Fix error in validating complex row-first hvncat (#45365)

Author: BioTurboNick

base/abstractarray.jl

@@ -2396,14 +2396,17 @@ function _typed_hvncat_dims(::Type{T}, dims::NTuple{N, Int}, row_first::Bool, as
     # validate shapes for lowest level of concatenation
     d = findfirst(>(1), dims)
     if d !== nothing # all dims are 1
+        if row_first && d < 3
+            d = d == 1 ? 2 : 1
+        end
         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)
+                    if cat_size(as[startelementi], dd) != cat_size(as[i], dd)
                         throw(ArgumentError("incompatible shape in element $i"))
                     end
                 end

test/abstractarray.jl

@@ -1543,6 +1543,8 @@ using Base: typed_hvncat
     # 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]]
+
+    @test [[1 2; 3 4] [5; 6]; [7 8] 9;;;] == [1 2 5; 3 4 6; 7 8 9;;;]
 end
 
 @testset "keepat!" begin