There is no member or method named _M_impl, how to use pvector to print STL vector of C++ compiled with clang++ and libc++,

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The test.cc is very simple:

#include <iostream>
#include <vector>

using namespace std;

int main(int argc, char *argv[])
{
  vector<int32_t> vec{1,2,3};

  return 0;
}

clang++ test.cc -std=c++17 -stdlib=libc++ -g

guo@dllab$ gdb ./a.out 
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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Type "show configuration" for configuration details.
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Reading symbols from ./a.out...done.
(gdb) l
1   #include <iostream>
2   #include <vector>
3   
4   using namespace std;
5   
6   int main(int argc, char *argv[])
7   {
8     vector<int32_t> vec{1,2,3};
9   
10    return 0;
(gdb) b 9
Breakpoint 1 at 0x400ca5: file test.cc, line 9.
(gdb) r
Starting program: /home/guo/a.out 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Breakpoint 1, main (argc=1, argv=0x7fffffffd718) at test.cc:10
10    return 0;
(gdb) p vec
$1 = {
  <std::__1::__vector_base<int, std::__1::allocator<int> >> = {
    <std::__1::__vector_base_common<true>> = {<No data fields>}, 
    members of std::__1::__vector_base<int, std::__1::allocator<int> >: 
    __begin_ = 0x603010, 
    __end_ = 0x60301c, 
    __end_cap_ = {
      <std::__1::__compressed_pair_elem<int*, 0, false>> = {
        __value_ = 0x60301c
      }, 
      <std::__1::__compressed_pair_elem<std::__1::allocator<int>, 1, true>> = {
        <std::__1::allocator<int>> = {<No data fields>}, <No data fields>}, <No data fields>}
  }, <No data fields>}
(gdb) pvector vec
There is no member or method named _M_impl.

I have installed stl-views-1.0.3.gdb via cat stl-views-1.0.3.gdb > ~/.gdbinit. So pvector is supposed to be used.

gdb c++
2 Answers

stl-views is an obsolete way of inspecting C++ containers in gdb. Instead, for libstdc++ there are python pretty printers which are part of gcc. In many Linux distributions they work out of the box. For libc++ there are no official pretty printers but there is a 3rd Party implementation which is recommended in libc++ documentation:

GDB does not support pretty-printing of libc++ symbols by default. Unfortunately libc++ does not provide pretty-printers itself. However there are 3rd party implementations available and although they are not officially supported by libc++ they may be useful to users.

Known 3rd Party Implementations Include:

Koutheir’s libc++ pretty-printers.
user_721780

In your launch.json add:

"setupCommands": [
            {
                "description": "Enable pretty-printing for gdb",
                "text": "-enable-pretty-printing",
                "ignoreFailures": true
            }
        ]

More about the launch.json you can see here.

user_120830510
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