[PATCH] D7895: Anonymous namespaces are missing import DW_TAG_imported_module.

[David Blaikie via llvm-commits]

On Tue, Aug 18, 2015 at 4:40 PM, Robinson, Paul <
Paul_Robinson at playstation.sony.com> wrote:

>
>
> How is this goal (adding imported modules for anonymous namespaces)
> consistent with the lack of imported modules for outer namespaces in nested
> ones? These two scenarios seem quite the same to me.
>
>
>
> Sadly, the "lack of imported modules for outer namespaces in nested ones"
> is nothing more than the normal way scoping works everywhere (with two
> minor exceptions).
>

Given DWARF's desire to be language neutral (does the DWARF spec talk about
name lookup at all? I don't think the idea of searching outer namespaces is
part of the DWARF spec, nor would it seem it should be... ) I would be
surprised if the DWARF spec baked in one choice of lookup like this.


> Therefore the scenarios are far from the same.  Searching upward from the
> current scope through the parents to the top is implicit and will remain
> so.  Even COBOL does that; it just doesn't make _all_ names visible to the
> inner scope.
>

Perhaps I've misunderstood - how does it pick which names are visible?


>
>
> For COBOL, I deliberately pretended the funky rules didn't exist. As far
> as DWARF is concerned, COBOL scoping works exactly like everything else.
>

Doesn't that break the user experience (in the same way that the user
experience for anonymous namespaces is broken for clients consuming Clang's
debug info and not explicitly accounting for unnamed namespaces in some
way)/make it inconsistent with the way name lookup works when using the
language directly?


> For C++, adding explicit imports for anonymous namespaces means as far as
> DWARF is concerned, C++ scoping work exactly like everything else.
>
>
>
> That is: What I want will make all languages behave simply and
> consistently, for DWARF scoping purposes.
>
> Is that such an undesirable result?
>

It's not a desirable result to me. (the COBOL example still seems like it's
a counterproof of this, even if it were a desirable goal)


>  Still haven't heard anybody say what would *break* if we have explicit
> imports.
>

We just add debug info where it's not needed. We usually try to avoid that,
even if it's a small amount (which I'm sure it is), so far I don't agree
with the motivation.

- David
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