This Repo demonstrates a bug found in conan version 2.0.3. The bug is caused by an override statement in a downstream package to a dependency which is never required as a real dependency in the result graph.
The follwing diagram illustrates the dependency graph:
In order to reproduce the bug, you need to build all three packages in the following order: 1. liba 2. libb 3. libc
using conan create .. Make sure you have conan 2.0.3 installed. The issue might exists in older versions as well but it was not tested.
During the build of libc you shoud receive the following error message:
Traceback (most recent call last):
File "/home/sin7hi/miniconda3/envs/conan2/lib/python3.10/site-packages/conan/cli/cli.py", line 272, in main
cli.run(args)
File "/home/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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/sin7hi/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:
It is interesting that the error occurs only in that specific dependency graph pattern. When removing libb or liba from libc, the package creation is fine. I'm not sure what the right behvior should look like. Maybe I would expect some warning but the build should succeed anyway even if the override dependency was never materialized.