Re: C++ nested class bug/questions

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-06-22 7:27 a.m., Willgerodt, Felix via Gdb wrote:
> Hello everyone,
> 
> I was debugging a program similar to the one attached and noticed a couple
> of unexpected things happening. I compiled it with ”-g -O0” and g++ 11.1.0
> (clang showed similar behaviour) and saw this:
> 
> (gdb) bt
> #0  DF::vvv (this=0x7fffffffd120) at foo.cc:11
> #1  0x0000555555555180 in foo () at foo.cc:16
> #2  0x00005555555551a7 in main () at foo.cc:20
> (gdb) ptype abcd
> type = class DF::FFFF {
>   private:
>     int ffff;
> }
> (gdb) ptype FFFF
> No symbol "FFFF" in current context.
> (gdb) ptype DF::
> FFFF   vvv()  
> (gdb) ptype DF::FFFF
> There is no field named FFFF
> (gdb) ptype 'DF::FFFF'
> type = class DF::FFFF {
>   private:
>     int ffff;
> }
> (gdb)
> 
> (The fourth command shows tab completion.)
> 
> The problems I see are:
> 1) I think it shouldn’t be DF::FFFF.
> 2) 'ptype FFFF’ should just work as it is in the current scope.
> 3) There shouldn’t be a need to quote DF:FFFF, right? Although that might just be a side-effect here.
> 4) The fact that a suggestion from tab completion doesn’t work is annoying. This is probably also be a side-effect.
> 
> Before debugging this further, I wanted to see if there are any comments/suggestions.
> Am I even right about point 1? I couldn’t really find anything definitive
> in my favourite cpp reference on this type of nesting. g++ and clang output FFFF as
> foo()::DF::vvv()::FFFF as far as I can see.
> 
> I don’t see any obvious problems in the dwarf that is produced.
> 
> Thanks,
> Felix

I'm not a reference on this topic, but at first glance I agree with you.

Simon