GDB support: Couldn't find method

GDB support: Couldn't find method

[Viesturs Veckalns]

Hello!
I compile a binary by linking a library:

-L${LIBDIR}/lib -lCompoundHisto

In the debug session the library is listed under

info sharedlibrary

Additionally, I requested to read symbols from the relevant source files by

set debug-file-directory ${LIBDIR}/interface
set debug-file-directory ${LIBDIR}/src

Nevertheless, I encounter the following problem:

p GetLevel(resultcode) -> GetHU(mo)
Couldn't find method CompoundHistoUnfolding::Level::GetHU

The methods are described in the source to build libCompoundHisto.so

What is wrong?

My gdb version is 7.11.
Viesturs

Re: GDB support: Couldn't find method

[Simon Marchi]

On 2018-08-04 07:48, Viesturs Veckalns wrote:
> Hello!
> I compile a binary by linking a library:
> 
> -L${LIBDIR}/lib -lCompoundHisto
> 
> In the debug session the library is listed under
> 
> info sharedlibrary
> 
> Additionally, I requested to read symbols from the relevant source 
> files by
> 
> set debug-file-directory ${LIBDIR}/interface
> set debug-file-directory ${LIBDIR}/src
> 
> Nevertheless, I encounter the following problem:
> 
> p GetLevel(resultcode) -> GetHU(mo)
> Couldn't find method CompoundHistoUnfolding::Level::GetHU
> 
> The methods are described in the source to build libCompoundHisto.so
> 
> What is wrong?
> 
> My gdb version is 7.11.
> Viesturs

Hi Viesturs,

A sanity check to see if GDB knows about any GetHU method would to do

   (gdb) ptype GetLevel(resultcode)

or

   (gdb) ptype CompoundHistoUnfolding::Level

Do you see GetHU listed?

Simon

RE: GDB support: Couldn't find method

[Viesturs Veckalns]

Hello Simon,
It turns out gdb does not know anything about class methods and nested classes loaded from the shared library:

(gdb) ptype GetLevel(resultcode)             
type = struct CompoundHistoUnfolding::Level {
    <incomplete type>
} *
(gdb) ptype CompoundHistoUnfolding::Level         
There is no field named Level

gdb can list members of class CompoundHistoUnfolding but does not know about classes interfaced with the #include directive:

(gdb) ptype CompoundHistoUnfolding       
type = class CompoundHistoUnfolding : public TNamed {
  private:
Python Exception <class 'gdb.error'> No type named TString.: 
    std::map<TString, HistoUnfolding*, std::less<TString>, std::allocator<std::pair<TString const, HistoUnfolding*> > > aggrbackgroundMC;
Python Exception <class 'gdb.error'> No type named HistoUnfolding*.: 
    std::vector<HistoUnfolding*, std::allocator<HistoUnfolding*> > _vbackgroundhistos;
Python Exception <class 'gdb.error'> No type named SampleDescriptor*.: 
    std::vector<SampleDescriptor*, std::allocator<SampleDescriptor*> > _expsyssamples;
    std::vector<SampleDescriptor*, std::allocator<SampleDescriptor*> > _markedsyssamples;
    HistoUnfoldingTH2 *totalbackground;
    char _signal_title[64];
...

How to proceed from this point?
Viesturs
________________________________________
From: Simon Marchi [simon.marchi@polymtl.ca]
Sent: 08 August 2018 02:27
To: Viesturs Veckalns
Cc: gdb@sourceware.org
Subject: Re: GDB support: Couldn't find method

On 2018-08-04 07:48, Viesturs Veckalns wrote:
> Hello!
> I compile a binary by linking a library:
>
> -L${LIBDIR}/lib -lCompoundHisto
>
> In the debug session the library is listed under
>
> info sharedlibrary
>
> Additionally, I requested to read symbols from the relevant source
> files by
>
> set debug-file-directory ${LIBDIR}/interface
> set debug-file-directory ${LIBDIR}/src
>
> Nevertheless, I encounter the following problem:
>
> p GetLevel(resultcode) -> GetHU(mo)
> Couldn't find method CompoundHistoUnfolding::Level::GetHU
>
> The methods are described in the source to build libCompoundHisto.so
>
> What is wrong?
>
> My gdb version is 7.11.
> Viesturs

Hi Viesturs,

A sanity check to see if GDB knows about any GetHU method would to do

   (gdb) ptype GetLevel(resultcode)

or

   (gdb) ptype CompoundHistoUnfolding::Level

Do you see GetHU listed?

Simon

Re: GDB support: Couldn't find method

[Simon Marchi]

On 2018-08-08 07:14, Viesturs Veckalns wrote:
> Hello Simon,
> It turns out gdb does not know anything about class methods and nested
> classes loaded from the shared library:
> 
> (gdb) ptype GetLevel(resultcode)
> type = struct CompoundHistoUnfolding::Level {
>     <incomplete type>
> } *
> (gdb) ptype CompoundHistoUnfolding::Level
> There is no field named Level
> 
> gdb can list members of class CompoundHistoUnfolding but does not know
> about classes interfaced with the #include directive:
> 
> (gdb) ptype CompoundHistoUnfolding
> type = class CompoundHistoUnfolding : public TNamed {
>   private:
> Python Exception <class 'gdb.error'> No type named TString.:
>     std::map<TString, HistoUnfolding*, std::less<TString>,
> std::allocator<std::pair<TString const, HistoUnfolding*> > >
> aggrbackgroundMC;
> Python Exception <class 'gdb.error'> No type named HistoUnfolding*.:
>     std::vector<HistoUnfolding*, std::allocator<HistoUnfolding*> >
> _vbackgroundhistos;
> Python Exception <class 'gdb.error'> No type named SampleDescriptor*.:
>     std::vector<SampleDescriptor*, std::allocator<SampleDescriptor*> >
> _expsyssamples;
>     std::vector<SampleDescriptor*, std::allocator<SampleDescriptor*> >
> _markedsyssamples;
>     HistoUnfoldingTH2 *totalbackground;
>     char _signal_title[64];
> ...
> 
> How to proceed from this point?
> Viesturs

I tried this simple code, and everything works as expected:

---

class Outer
{
   class Inner
   {
     int foo = 2;

   public:
     int getFoo() {
       return foo;
     }
   };

public:
   Inner getBar()
   {
     return Inner();
   }
};

int main()
{
   Outer o;
   return o.getBar().getFoo();
}

---

(gdb) p o.getBar().getFoo()
$2 = 2
(gdb) ptype Outer::Inner
type = class Outer::Inner {
   private:
     int foo;

   public:
     int getFoo(void);
}


To continue investigating, I would need a minimal reproducer, because at 
this point I can only do some very wild guessing.

Simon

Re: GDB support: Couldn't find method

[Pedro Alves]

On 08/04/2018 12:48 PM, Viesturs Veckalns wrote:
> Hello!
> I compile a binary by linking a library:
> 
> -L${LIBDIR}/lib -lCompoundHisto
> 
> In the debug session the library is listed under
> 
> info sharedlibrary
> 
> Additionally, I requested to read symbols from the relevant source files by
> 
> set debug-file-directory ${LIBDIR}/interface
> set debug-file-directory ${LIBDIR}/src

Note that "set debug-file-directory" is used to point GDB at
debug symbol files, not source files.  For the latter, you'd use
the "directory" command.

> 
> Nevertheless, I encounter the following problem:
> 
> p GetLevel(resultcode) -> GetHU(mo)
> Couldn't find method CompoundHistoUnfolding::Level::GetHU
> 
> The methods are described in the source to build libCompoundHisto.so
> 
> What is wrong?
> 
> My gdb version is 7.11.

Since it works for Simon downthread, and absent a more complete
reproducer, I'd suggest trying a newer GDB version.  7.11 is a few
releases behind by now.

Thanks,
Pedro Alves