[PATCH] D45244: Add missing vtable anchors

[David Blaikie via llvm-commits]

Hmm - yeah, I'm not sure what the criteria would be for mixing
rtti/no-rtti, etc.

On Sun, Apr 15, 2018 at 8:45 PM weiming zhao <wmzhao.code at gmail.com> wrote:

> It’s very similar to the issue described in
> http://lists.llvm.org/pipermail/llvm-dev/2016-February/095671.html
> My code has RTTI and LLVM doesn’t. During static linking, it hits the
> “undefined type info” error. After I put the anchors, the issues are
> solved. My guess the weak vtable and the mixed RTTI/no-RTTI confused the
> linker somehow. I don’t know the exact reason though.
>
>
> On Apr 15, 2018, at 7:55 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Sat, Apr 14, 2018 at 10:33 PM Weiming Zhao via Phabricator <
> reviews at reviews.llvm.org> wrote:
>
>> weimingz added a comment.
>>
>> In https://reviews.llvm.org/D45244#1064905, @dblaikie wrote:
>>
>> > Great - thanks for sticking with it, sorry for my dodgy explanations!
>> >
>> > If you're adding in anchors, are you using -Wweak-vtables to find them?
>> If you're pushing through to make LLVM (& hopefully Clang/other LLVM
>> subprojects) -Wweak-vtables clean, perhaps you can turn on the warning in
>> the CMake config once it's clean so we don't regress this again? (it'd also
>> be interesting to do some kind of analysis to see whether avoiding weak
>> vtables is /actually/ worthwhile - like maybe making a
>> temporary/local/non-committed change to change all the explicit anchors
>> into inline functions (unanchoring them) & see if builds are much larger or
>> longer, etc)
>>
>>
>> I got linker error when my code tries to statically link against some
>> LLVM libs (like libLLVMOrc). It's a good idea to turn on -Wweak-vtables to
>> check if we miss other cases. I will try it. Thanks
>>
>
> Hmm, I'm confused - you mean without these changes you were getting link
> errors due to vtable symbols for types with weak vtables? I'm not sure why
> that would be - your code should've been built with its own weak vtable, in
> that situation.
>
> - Dave
>
>
>>
>>
>> Repository:
>>   rL LLVM
>>
>> https://reviews.llvm.org/D45244
>
>
>
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