Resolve ambiguity for convert(::Type{<:Scalar}, ::StaticArray) (#808)

Author: Liozou

src/convert.jl

@@ -8,6 +8,7 @@
 
 # this covers most conversions and "statically-sized reshapes"
 @inline convert(::Type{SA}, sa::StaticArray) where {SA<:StaticArray} = SA(Tuple(sa))
+@inline convert(::Type{SA}, sa::StaticArray) where {SA<:Scalar} = SA((sa[],)) # disambiguation
 @inline convert(::Type{SA}, sa::SA) where {SA<:StaticArray} = sa
 @inline convert(::Type{SA}, x::Tuple) where {SA<:StaticArray} = SA(x) # convert -> constructor. Hopefully no loops...
 

test/ambiguities.jl

@@ -3,11 +3,11 @@
 
 const allowable_ambiguities =
     if VERSION < v"1.1"
-        4
+        3
     elseif VERSION < v"1.2"
-        2
-    else
         1
+    else
+        0
     end
 
 @test length(detect_ambiguities(Base, LinearAlgebra, StaticArrays)) <= allowable_ambiguities

test/convert.jl

@@ -14,4 +14,8 @@ end # testset
     # Issue #651
     @testinf SVector{0,Float64}(Any[]) === SVector{0,Float64}()
     @testinf SVector{0,Float64}(Int8[]) === SVector{0,Float64}()
+
+    # PR #808
+    @test Scalar{Int}[SVector{1,Int}(3), SVector{1,Float64}(2.0)] == [Scalar{Int}(3), Scalar{Int}(2)]
+    @test Scalar[SVector{1,Int}(3), SVector{1,Float64}(2.0)] == [Scalar{Int}(3), Scalar{Float64}(2.0)]
 end