[lldb-dev] RTTI does not work stable in LLDB.

Roman Popov via lldb-dev lldb-dev at lists.llvm.org
Mon Feb 6 10:00:28 PST 2017


Yes, that was my thought.

FYI, checked in GDB: it's working correctly on this testcase showing
correct dynamic type in both cases.

2017-02-06 9:48 GMT-08:00 Greg Clayton <gclayton at apple.com>:

> You have found a bug. It should be reporting this correctly but it isn’t.
> I verified it fails on MacOSX.
>
> Greg Clayton
>
> On Feb 5, 2017, at 1:19 PM, Roman Popov via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
>
> Hello,
> I'm observing very strange LLDB behavior: it does not always shows a
> correct dynamic type when I ask for.
>
> Originally I was working with LLDB 3.9, but it looks like trunk version
> behaves the same strange way.
>
> I was able to capture this behavior in a small code snippet:
>
> #include <iostream>
> #include <typeinfo>
>
> using namespace std;
>
> struct base_type {  virtual ~base_type(){} };
>
> template <class T1, class T2, unsigned SIZE>
> struct derived0 : base_type {};
>
> template <class T1, class T2>
> struct derived1 : base_type {};
>
> int main(int argc, char ** argv) {
>
>     base_type * bptr0 = new derived0<int, int, 1024>();
>     base_type * bptr1 = new derived1<int, int >();
>
>     cout << typeid(*bptr0).name() << endl;
>     cout << typeid(*bptr1).name() << endl;
>
>     return 0;
> }
>
>
> lldb --version
> lldb version 5.0.0 (http://llvm.org/svn/llvm-project/lldb/trunk revision
> 293398)
>   clang revision 293398
>   llvm revision 293398
>
>
> Testing in LLDB:
> (lldb) break set --file main.cpp --line 22
>
> (lldb) expression -d no-run --  bptr1
> (derived1<int, int> *) $2 = 0x0000000000614c40
>
> (lldb) expression -d no-run --  bptr0
> *(base_type *) $3 = 0x0000000000614c20*
>
>
> Can someone explain me why for bptr0 I dont get a  derived0<int, int,
> 1024> * as I expected?
>
>
> Thanks,
> Roman
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>
>
>
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