[bug] conan2 Assertion error when using override in downstream package in specific scenario

[nicosmd]

Environment details

• Operating System+version: Ubuntu 22.04
• Compiler+version: gcc 11.3.0
• Conan version: conan 2.0.3
• Python version: 3.10.9

Steps to reproduce

1. follow the instructions on: https://github.com/nicosmd/conan2-missing-override-bug

Logs

conan create .

======== Exporting recipe to the cache ========
libc/0.1: Exporting package recipe: /home/user/dev/conan2-missing-override-bug/libc/conanfile.py
libc/0.1: Copied 1 '.py' file: conanfile.py
libc/0.1: Exported to cache folder: /home/user/.conan2/p/libc131a61a3214d9/e
libc/0.1: Exported: libc/0.1#423a07067eef81c2ee8b320fd2cb100c (2023-04-05 19:50:45 UTC)

======== Input profiles ========
Profile host:
[settings]
arch=x86_64
build_type=Release
compiler=gcc
compiler.cppstd=gnu17
compiler.libcxx=libstdc++11
compiler.version=10
os=Linux
[options]
opencv*:with_ffmpeg=False
opencv*:with_gtk=False
[conf]
tools.cmake.cmake_layout:build_folder_vars=['settings.arch']

Profile build:
[settings]
arch=x86_64
build_type=Release
compiler=gcc
compiler.cppstd=gnu17
compiler.libcxx=libstdc++11
compiler.version=10
os=Linux
[options]
opencv*:with_ffmpeg=False
opencv*:with_gtk=False
[conf]
tools.cmake.cmake_layout:build_folder_vars=['settings.arch']


======== Computing dependency graph ========
Traceback (most recent call last):
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/cli/cli.py", line 272, in main
    cli.run(args)
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/cli/cli.py", line 171, in run
    command.run(self._conan_api, self._commands[command_argument].parser, args[0][1:])
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/cli/command.py", line 157, in run
    info = self._method(conan_api, parser, *args)
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/cli/commands/create.py", line 69, in create
    deps_graph = conan_api.graph.load_graph_requires(requires, tool_requires,
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/api/subapi/graph.py", line 123, in load_graph_requires
    deps_graph = self.load_graph(root_node, profile_host=profile_host,
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/api/subapi/graph.py", line 172, in load_graph
    deps_graph = builder.load_graph(root_node, profile_host, profile_build, lockfile)
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conans/client/graph/graph_builder.py", line 53, in load_graph
    new_node = self._expand_require(require, node, dep_graph, profile_host,
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conans/client/graph/graph_builder.py", line 100, in _expand_require
    node.propagate_closing_loop(require, prev_node)
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conans/client/graph/graph.py", line 82, in propagate_closing_loop
    prev_node.propagate_downstream(transitive.require, transitive.node, self)
  File "/home/user/miniconda3/envs/conan2/lib/python3.10/site-packages/conans/client/graph/graph.py", line 86, in propagate_downstream
    assert node is not None
AssertionError

ERROR:

[memsharded]

Thanks very much @nicosmd for your report, and specially for the detailed minimal repro case.

It was super helpful to quickly investigate and reproduce the issue. It was exactly the bad coincidence of having an override defined in the package that is a node in the graph that is closing a typical "diamond" structure, and this is why it doesn't happen for the other (majority) of cases when using overrides.

I have already been able to submit a fix in #13631 for next 2.0.4.

[nicosmd]

Thanks @memsharded , I'm very glad that I could help :) I'm closing the issue then since the fix is already submitted.