Make vec just return the argument for MVector and SizedVector. (#982)

* Make `vec` just return the argument for `MVector` and `SizedVector`.

* bump version

Author: mateuszbaran

Project.toml

@@ -1,6 +1,6 @@
 name = "StaticArrays"
 uuid = "90137ffa-7385-5640-81b9-e52037218182"
-version = "1.3.0"
+version = "1.3.1"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/abstractarray.jl

@@ -190,11 +190,17 @@ homogenize_shape(shape::Tuple{Vararg{HeterogeneousShape}}) = map(last, shape)
 @inline function reshape(a::StaticArray, s::Tuple{SOneTo,Vararg{SOneTo}})
     return __reshape(a, map(u -> last(u), s), homogenize_shape(s))
 end
-@inline function __reshape(a, shape, ::Size{S}) where {S}
-    return SizedArray{Tuple{S...}}(Base._reshape(a, shape))
+@inline function __reshape(a, shape, s::Size)
+    return _maybewrap_reshape(Base._reshape(a, shape), Size(a), s)
 end
-@inline function __reshape(a::SizedArray, shape, ::Size{S}) where {S}
-    return SizedArray{Tuple{S...}}(Base._reshape(a.data, shape))
+@inline function __reshape(a::SizedArray, shape, s::Size)
+    return _maybewrap_reshape(Base._reshape(a.data, shape), Size(a), s)
+end
+@inline function _maybewrap_reshape(a, ::Size{Sa}, ::Size{S}) where {Sa,S}
+    return SizedArray{Tuple{S...}}(a)
+end
+@inline function _maybewrap_reshape(a::StaticArray, ::Size{S}, ::Size{S}) where {S}
+    return a
 end
 
 reshape(a::Vector, ::Size{S}) where {S} = SizedArray{Tuple{S...}}(a)

test/abstractarray.jl

@@ -115,6 +115,11 @@ using StaticArrays, Test, LinearAlgebra
         @test_throws DimensionMismatch reshape([1 2 3], axes(SMatrix{2,2}(1,2,3,4)))
 
         @test @inferred(vec(SMatrix{2, 2}([1 2; 3 4])))::SVector{4,Int} == [1, 3, 2, 4]
+        a = @MVector [1, 2, 3, 4]
+        @test @inferred(vec(a)) === a
+
+        as = SizedVector(a)
+        @test @inferred(vec(as)) === as
 
         # AbstractArray
         # CartesianIndex