Make transpose/adjoint of Vec an error. (#103)

src/tensor_ops_errors.jl

@@ -2,3 +2,9 @@
 function Base.:*(S1::AbstractTensor, S2::AbstractTensor)
     error("use `⋅` (`\\cdot`) for single contraction and `⊡` (`\\boxdot`) for double contraction instead of `*`")
 end
+
+for f in (:transpose, :adjoint)
+    @eval function LinearAlgebra.$f(::Vec)
+        throw(ArgumentError("the (no-op) $($f) is discontinued for `Tensors.Vec`"))
+    end
+end

src/transpose.jl

@@ -20,8 +20,6 @@ julia> A'
  0.566237  0.460085
 ```
 """
-@inline Base.transpose(S::Vec) = S
-
 @inline function Base.transpose(S::Tensor{2, dim}) where {dim}
     Tensor{2, dim}(@inline function(i, j) @inbounds S[j,i]; end)
 end

test/test_misc.jl

@@ -494,4 +494,10 @@ end
     A2 = rand(Tensor{2, 2})
     @test_throws DimensionMismatch A + A2
     @test_throws DimensionMismatch AA - A
+
+    # transpose/adjoint of Vec
+    x = rand(Vec{3})
+    @test_throws ArgumentError x'
+    @test_throws ArgumentError transpose(x)
+    @test_throws ArgumentError adjoint(x)
 end # of testset

test/test_ops.jl

@@ -133,7 +133,6 @@ end # of testsection
 end # of testsection
 
 @testsection "transpose" begin
-    @test (@inferred transpose(a))::Vec{dim, T} ≈ a' ≈ a
     @test (@inferred transpose(A))::Tensor{2, dim, T} ≈ Array(A)'
     @test transpose(transpose(A)) ≈ A
     @test (@inferred transpose(A_sym))::SymmetricTensor{2, dim, T} ≈ A_sym ≈ Array(A_sym)'