fix vector indexing (#1143)

* fix vector indexing

* add test

* bump

---------

Co-authored-by: Pepijn de Vos <pepijn.devos@juliahub.com>
Co-authored-by: Pepijn de Vos <pepijn.devos@juliacomputing.com>

Author: pepijndevos

Project.toml

@@ -1,6 +1,6 @@
 name = "StaticArrays"
 uuid = "90137ffa-7385-5640-81b9-e52037218182"
-version = "1.5.19"
+version = "1.5.20"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/indexing.jl

@@ -59,7 +59,7 @@ end
         else
             ind_expr = :($ind_expr + $stride * (inds[$i] - 1))
         end
-        stride *= S[i]
+        stride *= Size(S)[i]
     end
     return quote
         @_propagate_inbounds_meta

test/matrix_multiply.jl

@@ -436,5 +436,7 @@ mul_wrappers = [
         outvec2f = Vector{Float64}(undef, 2)
         mul!(outvec2f, mf, vf2)
         @test outvec2f ≈ [10.0, 22.0]
+
+        @test mul!(@MArray([0.0]), Diagonal([1]), @MArray([2.0])) == @MArray([2.0])
     end
 end