[Bug debug/69755] New: Bad debug location with DW_OP_GNU_convert <0x0>

[nikolay.piskun at roguewave dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69755

            Bug ID: 69755
           Summary: Bad debug location with DW_OP_GNU_convert <0x0>
           Product: gcc
           Version: 5.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nikolay.piskun at roguewave dot com
  Target Milestone: ---

I compiled simple C++11 optimized program and get following location: 
    00000014 00000000004004c9 00000000004004d7 (DW_OP_addr: 601038;
DW_OP_GNU_deref_type: 4 <0x30>; DW_OP_GNU_convert <0x29>; DW_OP_GNU_convert
<0x0>; DW_OP_breg0 (rax): 0; DW_OP_plus; DW_OP_stack_value)
The value of variable 'r' in debugger is clearly wrong. I think starting from
DW_OP_GNU_convert <0x0>; everything is wrong.
I will attach sample program compiled with gcc 5.3.1 as :
 *** Compiling ../../src/tx_c++11_unnamed_type.cxx ***
 /usr/bin/g++    -MD -MP     -O3 -g  -std=c++11 -std=c++11     
  -c ../../src/tx_c++11_unnamed_type.cxx -o  tx_c++11_unnamed_type.o

*** Linking program tx_c++11_unnamed_type ***
 /usr/bin/g++      -O3 -g  -Wl,-disable-new-dtags -std=c++11 -std=c++11  
tx_c++11_unnamed_type.o tx_c++11_unnamed_type1.o    \
  -o tx_c++11_unnamed_type

cat  ../../src/tx_c++11_unnamed_type.hxx
template <class T> 
class X_t { 
  T t;
public:
  X_t() {t.x=25; t.y=1.1; }
  int func()
  {
    return (int) t.x;
  }
}; // class template
int func1();

cat ../../src/tx_c++11_unnamed_type.cxx
#include "tx_c++11_unnamed_type.hxx"
typedef struct {float x,y;} B; // type alias to an unnamed type
X_t<B> x2; // OK, 'B' names a type

static int func2()
{  
return x2.func(); 
}

int main(){
  int r = 0;
  r += func1();
  r += func2();
  return r;
}