Merge pull request #17089 from pkofod/densecat

Make concatenation of vectors of matrices return dense matrix.

Author: tkelman

base/array.jl

@@ -731,6 +731,8 @@ hcat{T}(A::Union{Matrix{T}, Vector{T}}...) = typed_hcat(T, A...)
 vcat(A::Union{Matrix, Vector}...) = typed_vcat(promote_eltype(A...), A...)
 vcat{T}(A::Union{Matrix{T}, Vector{T}}...) = typed_vcat(T, A...)
 
+hvcat(rows::Tuple{Vararg{Int}}, xs::Vector...) = typed_hvcat(promote_eltype(xs...), rows, xs...)
+hvcat{T}(rows::Tuple{Vararg{Int}}, xs::Vector{T}...) = typed_hvcat(T, rows, xs...)
 
 hvcat(rows::Tuple{Vararg{Int}}, xs::Matrix...) = typed_hvcat(promote_eltype(xs...), rows, xs...)
 hvcat{T}(rows::Tuple{Vararg{Int}}, xs::Matrix{T}...) = typed_hvcat(T, rows, xs...)

test/abstractarray.jl

@@ -612,3 +612,20 @@ A = TSlowNIndexes(rand(2,2))
 @test @inferred(indices(rand(3,2), 1)) == 1:3
 @test @inferred(indices(rand(3,2), 2)) == 1:2
 @test @inferred(indices(rand(3,2), 3)) == 1:1
+
+#17088
+let
+    n = 10
+    M = rand(n, n)
+    # vector of vectors
+    v = [[M]; [M]] # using vcat
+    @test size(v) == (2,)
+    @test !issparse(v)
+    # matrix of vectors
+    m1 = [[M] [M]] # using hcat
+    m2 = [[M] [M];] # using hvcat
+    @test m1 == m2
+    @test size(m1) == (1,2)
+    @test !issparse(m1)
+    @test !issparse(m2)
+end