julia> VERSION
v"1.2.0-DEV.212"

julia> A = [1 2; 3 4]
2×2 Array{Int64,2}:
 1  2
 3  4
julia> X = Symmetric(A, :L)
2×2 Symmetric{Int64,Array{Int64,2}}:
 1  3
 3  4
julia> Symmetric(X) == Symmetric(X, :U) # result contradicts 2.
ERROR: ArgumentError: Cannot construct Symmetric; uplo doesn't match
Stacktrace:
 [1] Symmetric(::Symmetric{Int64,Array{Int64,2}}, ::Symbol) at
      /home/julia/julia/usr/share/julia/stdlib/v1.2/LinearAlgebra/src/symmetric.jl:162
 [2] top-level scope at REPL[87]:1

julia> Symmetric(X) == Symmetric(Matrix(X))
true
julia> Symmetric(Matrix(X), :U) # result contradicts 1.
2×2 Symmetric{Int64,Array{Int64,2}}:
 1  3
 3  4
julia> Symmetric(Matrix(X), :L)
2×2 Symmetric{Int64,Array{Int64,2}}:
 1  3
 3  4