python - Nixos:如何获得带有包中包含的调试信息的 python？

Question

我正在尝试在 NixOS 上进行 cython 调试。我可以轻松地将 cython 安装在 nix-shell 中(为简化示例而选择)，如下所示:

$ nix-shell -p 'python27.withPackages( p: [ p.cython ])'

$ cat /nix/store/s0w3phb2saixi0a9bzk8pjbczjaz8d7r-python-2.7.14-env/bin/python
#! /nix/store/jgw8hxx7wzkyhb2dr9hwsd9h2caaasdc-bash-4.4-p12/bin/bash -e
export PYTHONHOME="/nix/store/s0w3phb2saixi0a9bzk8pjbczjaz8d7r-python-2.7.14-env"
export PYTHONNOUSERSITE="true"
exec "/nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python"  "${extraFlagsArray[@]}" "$@"

然后我们做一个普通的 python 的 nix-shell，看看我们得到的是什么版本的 python。

[henry@bollum:~/Projects/eyeserver/nixshell]$ nix-shell -p 'python27'
$ which python
/nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python
#          ^^^^^^^
#          non-debug

一切都很好——在这两种情况下我们都得到了一个非调试 python。如果我们 gdb 它，我们得到(没有找到调试符号)。请参阅最后一行。

$ gdb 
/nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python
GNU gdb (GDB) 8.0.1
Copyright (C) 2017 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python...(no debugging symbols found)...done.

当我们单独在 python 上使用 enableDebugging 时，我们会得到不同的结果。 $ nix-shell -p 'enableDebugging python27'

$ which python
/nix/store/a4wd8mcpqr54hmw0x95fw8fhvk8avh5a-python-2.7.14/bin/python
#          ^^^^^^
#          debug

$ gdb 
/nix/store/a4wd8mcpqr54hmw0x95fw8fhvk8avh5a-python-2.7.14/bin/python
GNU gdb (GDB) 8.0.1
...
Reading symbols from /nix/store/a4wd8mcpqr54hmw0x95fw8fhvk8avh5a-python-2.7.14/bin/python...done.

当我们尝试使用包含的 cython(或任何其他包)执行此操作时，问题就来了。
$ nix-shell -p '(enableDebugging python27).withPackages( p: [ p.cython ])'

$ cat `which python`
#! /nix/store/jgw8hxx7wzkyhb2dr9hwsd9h2caaasdc-bash-4.4-p12/bin/bash -e
export PYTHONHOME="/nix/store/s0w3phb2saixi0a9bzk8pjbczjaz8d7r-python-2.7.14-env"
export PYTHONNOUSERSITE="true"
exec "/nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python"  "${extraFlagsArray[@]}" "$@"
#                ^^^^^^^
#                non-debug
$ gdb /nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python
GNU gdb (GDB) 8.0.1
...
Reading symbols from /nix/store/i3bx1iw2d0i3vh9sa1nf92ynlrw324w8-python-2.7.14/bin/python...(no debugging symbols found)...done.
(gdb) 
quit

环境中的 python 版本现在是非调试版本，尝试调试它会很可怕(找不到调试符号)。这使得 gdb 对于调试 cython 程序的用处大打折扣。

Answer 1

解决方案

with import <nixpkgs> {};

let
   self = enableDebugging python;
in [ gdb ((python.override{inherit self;}).withPackages(ps: with ps; [ cython ])) ]

包装器中引用的可执行文件现在具有调试符号。

背景

如果我们查看 pkgs/all-packages.nix，我们会看到 enableDebugging 函数的实现:

enableDebugging = pkg: pkg.override { stdenv = stdenvAdapters.keepDebugInfo pkg.stdenv; };

它覆盖单个推导以使用不同的 stdenv。在您的情况下，您想覆盖 Python 解释器，它依赖于使用 python.withPackages 获得的派生。

您尝试使用 enableDebugging python 的方向是正确的，但是，python.withPackages 使用了对需要更新的 python 的引用