Macro Inconsistency using Module Qualification

[twavv]

For context, this is for JuliaGizmos/WebIO.jl#306.

Simplified, we want to have a macro that accepts a do-block argument.

macro foo(f, ex...)
    @show f
	return :(nothing)
end

This works just fine.

julia> @foo(a, b, c) do x, y, z
           println("Hello!")
       end
f = :((x, y, z)->begin
          #= REPL[2]:2 =#
          println("Hello!")
      end)

However, things get more interesting when we have to qualify the name of @foo because it's in a module.

julia> module FooModule
       macro foo(f, ex...)
           @show f
           return :(nothing)
       end
       end

Putting the @ on the macro name doesn't work.

julia> FooModule.@foo(a, b, c) do x, y z
           println("Hello!")
       end
ERROR: syntax: invalid syntax "FooModule.@foo # REPL[2], line 1 a b c do x, y
    # REPL[2], line 1
    z
    # REPL[2], line 2
    println("Hello!")
end"

while putting the @ in front of the module name does.

julia> @FooModule.foo(a, b, c) do x, y, z
           println("Hello!")
       end
f = :((x, y, z)->begin
          #= REPL[6]:2 =#
          println("Hello!")
      end)

The macro expansion returns strangeness (it should return Main.FooModule.nothing since that's... what the macro expands to).

julia> @macroexpand FooModule.@foo(a, b, c) do x, y z
           println("Hello!")
       end
:($(Expr(:., :FooModule, :($(Expr(:copyast, :($(QuoteNode(:(#= REPL[3]:1 =# @foo a b c do x, y
      #= REPL[3]:1 =#
      z
      #= REPL[3]:2 =#
      println("Hello!")
  end))))))))))

It's worth nothing that the macro expansion of @FooModule.foo doesn't even work.

This is adjacent to #1769.