From 55026e07834c0d12396045b59878fc56a3a3ab49 Mon Sep 17 00:00:00 2001
From: Robert Scott <code@humanleg.org.uk>
Date: Sun, 12 Jul 2020 14:40:09 +0100
Subject: [PATCH 1/3] cpython: set separateDebugInfo, explicitly stripping
 static libpython*.a

debug info can't be separated from a static library and would otherwise be
left in place by a separateDebugInfo build. force its removal here to save
space in output.
---
 pkgs/development/interpreters/python/cpython/default.nix | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkgs/development/interpreters/python/cpython/default.nix b/pkgs/development/interpreters/python/cpython/default.nix
index 76a66a648d84..99d0ae24b7b8 100644
--- a/pkgs/development/interpreters/python/cpython/default.nix
+++ b/pkgs/development/interpreters/python/cpython/default.nix
@@ -411,6 +411,11 @@ in with passthru; stdenv.mkDerivation {
     # This allows build Python to import host Python's sysconfigdata
     mkdir -p "$out/${sitePackages}"
     ln -s "$out/lib/${libPrefix}/"_sysconfigdata*.py "$out/${sitePackages}/"
+
+    # debug info can't be separated from a static library and would otherwise be
+    # left in place by a separateDebugInfo build. force its removal here to save
+    # space in output.
+    $STRIP -S $out/lib/${libPrefix}/config-*/libpython*.a || true
     '' + optionalString stripConfig ''
     rm -R $out/bin/python*-config $out/lib/python*/config-*
     '' + optionalString stripIdlelib ''
@@ -465,6 +470,8 @@ in with passthru; stdenv.mkDerivation {
     pythonForBuild buildPackages.bash
   ];
 
+  separateDebugInfo = true;
+
   inherit passthru;
 
   enableParallelBuilding = true;

From 049444dc6b48fcebddbb90d7ab01c5a6fba85902 Mon Sep 17 00:00:00 2001
From: Robert Scott <code@humanleg.org.uk>
Date: Tue, 26 Jan 2021 20:39:00 +0000
Subject: [PATCH 2/3] cpython: expose libpython.py for debugging from gdb

---
 pkgs/development/interpreters/python/cpython/default.nix | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkgs/development/interpreters/python/cpython/default.nix b/pkgs/development/interpreters/python/cpython/default.nix
index 99d0ae24b7b8..3d4cee22b2c2 100644
--- a/pkgs/development/interpreters/python/cpython/default.nix
+++ b/pkgs/development/interpreters/python/cpython/default.nix
@@ -445,6 +445,13 @@ in with passthru; stdenv.mkDerivation {
     find $out -name "*.py" | ${pythonForBuildInterpreter} -m compileall -q -f -x "lib2to3" -i -
     find $out -name "*.py" | ${pythonForBuildInterpreter} -O  -m compileall -q -f -x "lib2to3" -i -
     find $out -name "*.py" | ${pythonForBuildInterpreter} -OO -m compileall -q -f -x "lib2to3" -i -
+    '' + ''
+    # *strip* shebang from libpython gdb script - it should be dual-syntax and
+    # interpretable by whatever python the gdb in question is using, which may
+    # not even match the major version of this python. doing this after the
+    # bytecode compilations for the same reason - we don't want bytecode generated.
+    mkdir -p $out/share/gdb
+    sed '/^#!/d' Tools/gdb/libpython.py > $out/share/gdb/libpython.py
   '';
 
   preFixup = lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''

From f8831c10debea095db177c6d65c1b0e50434227e Mon Sep 17 00:00:00 2001
From: Robert Scott <code@humanleg.org.uk>
Date: Tue, 26 Jan 2021 20:41:39 +0000
Subject: [PATCH 3/3] python3.tests: add cpython-gdb test

---
 .../development/interpreters/python/tests.nix | 18 ++++++++++-----
 .../python/tests/test_cpython_gdb/default.nix | 22 +++++++++++++++++++
 2 files changed, 34 insertions(+), 6 deletions(-)
 create mode 100644 pkgs/development/interpreters/python/tests/test_cpython_gdb/default.nix

diff --git a/pkgs/development/interpreters/python/tests.nix b/pkgs/development/interpreters/python/tests.nix
index 872123338f8c..764ab29e919b 100644
--- a/pkgs/development/interpreters/python/tests.nix
+++ b/pkgs/development/interpreters/python/tests.nix
@@ -94,12 +94,18 @@ let
 
   # Integration tests involving the package set.
   # All PyPy package builds are broken at the moment
-  integrationTests = lib.optionalAttrs (python.pythonAtLeast "3.7"  && (!python.isPyPy)) rec {
-    # Before the addition of NIX_PYTHONPREFIX mypy was broken with typed packages
-    nix-pythonprefix-mypy = callPackage ./tests/test_nix_pythonprefix {
-      interpreter = python;
-    };
-  };
+  integrationTests = lib.optionalAttrs (!python.isPyPy) (
+    lib.optionalAttrs (python.isPy3k && !stdenv.isDarwin) { # darwin has no split-debug
+      cpython-gdb = callPackage ./tests/test_cpython_gdb {
+        interpreter = python;
+      };
+    } // lib.optionalAttrs (python.pythonAtLeast "3.7") rec {
+      # Before the addition of NIX_PYTHONPREFIX mypy was broken with typed packages
+      nix-pythonprefix-mypy = callPackage ./tests/test_nix_pythonprefix {
+        interpreter = python;
+      };
+    }
+  );
 
   # Tests to ensure overriding works as expected.
   overrideTests = let
diff --git a/pkgs/development/interpreters/python/tests/test_cpython_gdb/default.nix b/pkgs/development/interpreters/python/tests/test_cpython_gdb/default.nix
new file mode 100644
index 000000000000..0254d843a4cf
--- /dev/null
+++ b/pkgs/development/interpreters/python/tests/test_cpython_gdb/default.nix
@@ -0,0 +1,22 @@
+{ interpreter, lib, gdb, writeText, runCommand }:
+
+let
+  crashme-py = writeText "crashme.py" ''
+    import ctypes
+
+    def sentinel_foo_bar():
+        ctypes.memset(0, 1, 1)
+
+    sentinel_foo_bar()
+  '';
+in runCommand "python-gdb" {} ''
+  # test that gdb is able to recover the python stack frame of this segfault
+  ${gdb}/bin/gdb -batch -ex 'set debug-file-directory ${interpreter.debug}/lib/debug' \
+    -ex 'source ${interpreter}/share/gdb/libpython.py' \
+    -ex r \
+    -ex py-bt \
+    --args ${interpreter}/bin/python ${crashme-py} | grep 'in sentinel_foo_bar' > /dev/null
+
+  # success.
+  touch $out
+''