A bug with using M: a as b

[tkf]

baremodule M1
    module Inner
        macro dummy end
    end
    using .Inner: @dummy as @sync
    # const var"@sync" = Inner.var"@dummy"  # this works
end

baremodule M2
    using ..M1: @sync
end

using Test
@test M2.var"@sync" === M1.var"@sync"

fails with

  Expression: Demo2.var"@sync" === Demo.var"@sync"
   Evaluated: var"@sync" === Main.Demo.Inner.var"@dummy"

[Pangoraw]

Seems like it is caused by the same problem as #43290 with a possible fix in #43291

Using #43291, both lhs and rhs resolve to the same binding:

julia> @test M2.var"@sync" === M1.var"@sync"
Test Passed
  Expression: M2.var"@sync" === M1.var"@sync"
   Evaluated: Main.M1.Inner.var"@dummy" === Main.M1.Inner.var"@dummy"