Add convert() methods for Matrix from Vector and RowVector

Author: staticfloat

base/array.jl

@@ -320,6 +320,7 @@ oneunit(x::AbstractMatrix{T}) where {T} = _one(oneunit(T), x)
 
 convert(::Type{Vector}, x::AbstractVector{T}) where {T} = convert(Vector{T}, x)
 convert(::Type{Matrix}, x::AbstractMatrix{T}) where {T} = convert(Matrix{T}, x)
+convert(::Type{Matrix}, x::Vector) = Matrix(reshape(x, :, 1))
 
 convert(::Type{Array{T}}, x::Array{T,n}) where {T,n} = x
 convert(::Type{Array{T,n}}, x::Array{T,n}) where {T,n} = x

base/linalg/rowvector.jl

@@ -44,6 +44,9 @@ const ConjRowVector{T,CV<:ConjVector} = RowVector{T,CV}
     RowVector{T}(Vector{transpose_type(T)}(n[2])) :
     error("RowVector expects 1×N size, got $n")
 
+# Convenience constructor to Matrix
+convert(::Type{Matrix}, x::RowVector) = Matrix(reshape(x, 1, :))
+
 # Conversion of underlying storage
 convert(::Type{RowVector{T,V}}, rowvec::RowVector) where {T,V<:AbstractVector} =
     RowVector{T,V}(convert(V,rowvec.vec))

test/arrayops.jl

@@ -191,6 +191,13 @@ end
     @test convert(Vector{Float64}, b) == b
 end
 
+@testset "conversion from Vector/RowVector to Matrix (#21977)" begin
+    a = Vector([1, 2, 3])
+    am = Matrix([1; 2; 3])
+    @test convert(Matrix, a) == am
+    @test convert(Matrix, a') == am'
+end
+
 @testset "operations with IndexLinear ReshapedArray" begin
     b = collect(1:12)
     a = Base.ReshapedArray(b, (4,3), ())