Ensure static array constructors create copies

Author: c42f

src/convert.jl

@@ -1,7 +1,8 @@
 (::Type{SA})(x::Tuple{Tuple{Tuple{<:Tuple}}}) where {SA <: StaticArray} = error("No precise constructor for $SA found. Length of input was $(length(x[1][1][1])).")
 
 @inline (::Type{SA})(x...) where {SA <: StaticArray} = SA(x)
-@inline (::Type{SA})(a::AbstractArray) where {SA <: StaticArray} = convert(SA, a) # Is this a good idea?
+@inline (::Type{SA})(a::StaticArray) where {SA<:StaticArray} = SA(Tuple(a))
+@inline (::Type{SA})(a::AbstractArray) where {SA <: StaticArray} = convert(SA, a)
 
 # this covers most conversions and "statically-sized reshapes"
 @inline convert(::Type{SA}, sa::StaticArray) where {SA<:StaticArray} = SA(Tuple(sa))

test/MVector.jl

@@ -16,6 +16,10 @@
         @test MVector((1,)).data === (1,)
         @test MVector((1.0,)).data === (1.0,)
 
+        # Constructors should create a copy (#335)
+        v = MVector(1,2)
+        @test MVector(v) !== v && MVector(v) == v
+
         @test ((@MVector [1.0])::MVector{1}).data === (1.0,)
         @test ((@MVector [1, 2, 3])::MVector{3}).data === (1, 2, 3)
         @test ((@MVector Float64[1,2,3])::MVector{3}).data === (1.0, 2.0, 3.0)