<p dir="auto">Here is a minimal working example.</p>
<div class="highlight highlight-source-julia notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="module MWE

module A
    struct S
        x
    end
    export S
end

module B
    using ..A
    f(x::S) = x  # stops &quot;working&quot; if I comment it out
    S() = S(1)
end

end  # module

MWE.A.S()  # works!"><pre class="notranslate"><span class="pl-k">module</span> MWE

<span class="pl-k">module</span> A
    <span class="pl-k">struct</span> S
        x
    <span class="pl-k">end</span>
    <span class="pl-k">export</span> S
<span class="pl-k">end</span>

<span class="pl-k">module</span> B
    <span class="pl-k">using</span> <span class="pl-k">..</span>A
    <span class="pl-en">f</span>(x<span class="pl-k">::</span><span class="pl-c1">S</span>) <span class="pl-k">=</span> x  <span class="pl-c"><span class="pl-c">#</span> stops "working" if I comment it out</span>
    <span class="pl-en">S</span>() <span class="pl-k">=</span> <span class="pl-c1">S</span>(<span class="pl-c1">1</span>)
<span class="pl-k">end</span>

<span class="pl-k">end</span>  <span class="pl-c"><span class="pl-c">#</span> module</span>

MWE<span class="pl-k">.</span>A<span class="pl-k">.</span><span class="pl-c1">S</span>()  <span class="pl-c"><span class="pl-c">#</span> works!</span></pre></div>
<p dir="auto">I tried to find if the issue is already posted but I couldn't find any.  I checked the MWE with 1.1.0-DEV.98 and 1.0.0.</p>
<p dir="auto">Not sure if this is intended:</p>
<div class="highlight highlight-source-julia notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="julia&gt; UUID
ERROR: UndefVarError: UUID not defined

julia&gt; using Random: UUID

julia&gt; UUID(x::String) = UUID(rand(UInt128)) # OK?
UUID

julia&gt; UUID(&quot;foo&quot;)
8c68d00a-33d1-777d-c4a1-0a41759d1581

julia&gt; using Base: getindex

julia&gt; struct Foo end

julia&gt; getindex(::Foo) = print(&quot;Hello&quot;)
ERROR: error in method definition: function Base.getindex must be explicitly imported to be extended"><pre class="notranslate">julia<span class="pl-k">&gt;</span> UUID
ERROR<span class="pl-k">:</span> UndefVarError<span class="pl-k">:</span> UUID not defined

julia<span class="pl-k">&gt;</span> <span class="pl-k">using</span> Random<span class="pl-k">:</span> UUID

julia<span class="pl-k">&gt;</span> <span class="pl-en">UUID</span>(x<span class="pl-k">::</span><span class="pl-c1">String</span>) <span class="pl-k">=</span> <span class="pl-c1">UUID</span>(<span class="pl-c1">rand</span>(UInt128)) <span class="pl-c"><span class="pl-c">#</span> OK?</span>
UUID

julia<span class="pl-k">&gt;</span> <span class="pl-c1">UUID</span>(<span class="pl-s"><span class="pl-pds">"</span>foo<span class="pl-pds">"</span></span>)
<span class="pl-c1">8</span>c68d00a<span class="pl-k">-</span><span class="pl-c1">33</span>d1<span class="pl-k">-</span><span class="pl-c1">777</span>d<span class="pl-k">-</span>c4a1<span class="pl-k">-</span><span class="pl-c1">0</span>a41759d1581

julia<span class="pl-k">&gt;</span> <span class="pl-k">using</span> Base<span class="pl-k">:</span> getindex

julia<span class="pl-k">&gt;</span> <span class="pl-k">struct</span> Foo <span class="pl-k">end</span>

julia<span class="pl-k">&gt;</span> <span class="pl-en">getindex</span>(<span class="pl-k">::</span><span class="pl-c1">Foo</span>) <span class="pl-k">=</span> <span class="pl-c1">print</span>(<span class="pl-s"><span class="pl-pds">"</span>Hello<span class="pl-pds">"</span></span>)
ERROR<span class="pl-k">:</span> error <span class="pl-k">in</span> method definition<span class="pl-k">:</span> <span class="pl-k">function</span> Base<span class="pl-k">.</span>getindex must be explicitly imported to be extended</pre></div>