Fix adjoint and transpose for 0×0 matrix, fixes #1066 (#1067)

Author: hyrodium

src/linalg.jl

@@ -69,15 +69,12 @@ end
 @inline transpose(a::Adjoint{<:Any,<:Union{StaticVector,StaticMatrix}}) = conj(a.parent)
 @inline transpose(a::Adjoint{<:Real,<:Union{StaticVector,StaticMatrix}}) = a.parent
 
-@generated function _transpose(::Size{S}, m::StaticMatrix) where {S}
-    Snew = (S[2], S[1])
-
-    exprs = [:(transpose(m[$(LinearIndices(S)[j1, j2])])) for j2 = 1:S[2], j1 = 1:S[1]]
-
+@generated function _transpose(::Size{S}, m::StaticMatrix{n1, n2, T}) where {n1, n2, S, T}
+    exprs = [:(transpose(m[$(LinearIndices(S)[j1, j2])])) for j2 in 1:n2, j1 in 1:n1]
     return quote
         $(Expr(:meta, :inline))
         elements = tuple($(exprs...))
-        @inbounds return similar_type($m, eltype(elements), Size($Snew))(elements)
+        @inbounds return similar_type($m, Base.promote_op(transpose, T), Size($(n2,n1)))(elements)
     end
 end
 
@@ -86,15 +83,12 @@ end
 @inline adjoint(a::Transpose{<:Real,<:Union{StaticVector,StaticMatrix}}) = a.parent
 @inline adjoint(a::Adjoint{<:Any,<:Union{StaticVector,StaticMatrix}}) = a.parent
 
-@generated function _adjoint(::Size{S}, m::StaticMatrix) where {S}
-    Snew = (S[2], S[1])
-
-    exprs = [:(adjoint(m[$(LinearIndices(S)[j1, j2])])) for j2 = 1:S[2], j1 = 1:S[1]]
-
+@generated function _adjoint(::Size{S}, m::StaticMatrix{n1, n2, T}) where {n1, n2, S, T}
+    exprs = [:(adjoint(m[$(LinearIndices(S)[j1, j2])])) for j2 in 1:n2, j1 in 1:n1]
     return quote
         $(Expr(:meta, :inline))
         elements = tuple($(exprs...))
-        @inbounds return similar_type($m, eltype(elements), Size($Snew))(elements)
+        @inbounds return similar_type($m, Base.promote_op(adjoint, T), Size($(n2,n1)))(elements)
     end
 end
 

test/linalg.jl

@@ -225,6 +225,14 @@ StaticArrays.similar_type(::Union{RotMat2,Type{RotMat2}}) = SMatrix{2,2,Float64,
         # Recursive adjoint/transpose correctly handles eltype (#708)
         @test (@inferred(adjoint(SMatrix{2,2}(fill([1,2], 2,2)))))::SMatrix == SMatrix{2,2}(fill(adjoint([1,2]), 2,2))
         @test (@inferred(transpose(SMatrix{2,2}(fill([1,2], 2,2)))))::SMatrix == SMatrix{2,2}(fill(transpose([1,2]), 2,2))
+
+        # 0×0 matrix
+        for T in (SMatrix{0,0,Float64}, MMatrix{0,0,Float64}, SizedMatrix{0,0,Float64})
+            m = T()
+            @test adjoint(m)::T == transpose(m)::T == m
+        end
+        @test adjoint(SMatrix{0,0,Vector{Int}}()) isa SMatrix{0,0,Adjoint{Int,Vector{Int}}}
+        @test transpose(SMatrix{0,0,Vector{Int}}()) isa SMatrix{0,0,Transpose{Int,Vector{Int}}}
     end
 
     @testset "normalization" begin