Use eltype in adjoint matvec

Author: jishnub

src/matmul.jl

@@ -932,7 +932,7 @@ function __generic_matvecmul!(f::F, C::AbstractVector, A::AbstractVecOrMat, B::A
     @inbounds begin
         if length(B) == 0
             for k = eachindex(C)
-                @stable_muladdmul _modify!(MulAddMul(alpha,beta), false, C, k)
+                @stable_muladdmul _modify!(MulAddMul(alpha,beta), zero(eltype(C)), C, k)
             end
         else
             for k = eachindex(C)

test/matmul.jl

@@ -1180,6 +1180,9 @@ end
     w = similar(v, size(A,1))
     mul!(w, A, v)
     @test all(iszero, w)
+    A = fill(m, 0, 2)
+    mul!(w, A', v)
+    @test all(iszero, w)
 end
 
 end # module TestMatmul