Refine MatchSpec validation to avoid incompatibilities with libmamba's parser

conda_libmamba_solver/solver.py

@@ -482,7 +482,9 @@ def _specs_to_tasks_add(self, in_state: SolverInputState, out_state: SolverOutpu
                 continue  # ignore virtual packages
             installed: PackageRecord = in_state.installed.get(name)
             if installed:
-                installed_spec_str = self._spec_to_str(installed.to_match_spec())
+                installed_spec_str = self._spec_to_str(
+                    self._check_spec_compat(installed.to_match_spec())
+                )
             else:
                 installed_spec_str = None
             requested: MatchSpec = self._check_spec_compat(in_state.requested.get(name))
@@ -925,18 +927,34 @@ def _check_spec_compat(self, match_spec: Union[MatchSpec, None]) -> Union[MatchS
         if match_spec is None:
             return None
         supported = "name", "version", "build", "channel", "subdir"
+        droppable = ("url",)
         unsupported_but_set = []
+        to_drop = set()
+        to_keep = {}
         for field in match_spec.FIELD_NAMES:
             value = match_spec.get_raw_value(field)
-            if value and field not in supported:
-                unsupported_but_set.append(field)
+            if value:
+                if (
+                    (field == "channel" and str(value) == "<unknown>")
+                    or (field == "subdir" and "channel" in to_drop)
+                    or field in droppable
+                ):
+                    # These make libmamba segfault but don't add useful info
+                    to_drop.add(field)
+                elif field not in supported:
+                    unsupported_but_set.append(field)
+                else:
+                    to_keep[field] = value
         if unsupported_but_set:
             raise InvalidMatchSpec(
                 match_spec,
                 "Libmamba only supports a subset of the MatchSpec interface for now. "
                 f"You can only use {supported}, but you tried to use "
                 f"{tuple(unsupported_but_set)}.",
             )
+        if to_drop:
+            log.debug("Dropping unsupported fields from %s: %s", match_spec, sorted(to_drop))
+            match_spec = MatchSpec(**to_keep)
         if (
             match_spec.get_raw_value("channel") == "defaults"
             and context.default_channels == DEFAULT_CHANNELS

news/421-matchspec-validation

@@ -0,0 +1,19 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Do not raise error if an unsupported `MatchSpec` field can be safely dropped instead. (#418 via #421)
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>

tests/test_channels.py

@@ -13,7 +13,11 @@
 from conda.common.io import env_vars
 from conda.core.prefix_data import PrefixData
 from conda.models.channel import Channel
-from conda.testing.integration import _get_temp_prefix, make_temp_env
+from conda.testing.integration import (
+    _get_temp_prefix,
+    make_temp_env,
+    package_is_installed,
+)
 from conda.testing.integration import run_command as conda_inprocess
 
 from .channel_testing.helpers import http_server_auth_basic  # noqa: F401
@@ -298,3 +302,18 @@ def test_http_server_auth_token_in_defaults(http_server_auth_token):
             condarc.write_text(condarc_contents)
         else:
             condarc.unlink()
+
+
+def test_unknown_channels_do_not_crash(tmp_path):
+    "https://github.com/conda/conda-libmamba-solver/issues/418"
+    DATA = Path(__file__).parent / "data"
+    test_pkg = DATA / "mamba_repo" / "noarch" / "test-package-0.1-0.tar.bz2"
+    with make_temp_env("ca-certificates") as prefix:
+        # copy pkg to a new non-channel-like location without repodata around to obtain
+        # '<unknown>' channel and reproduce the issue
+        temp_pkg = Path(prefix, "test-package-0.1-0.tar.bz2")
+        shutil.copy(test_pkg, temp_pkg)
+        conda_inprocess("install", prefix, str(temp_pkg))
+        assert package_is_installed(prefix, "test-package")
+        conda_inprocess("install", prefix, "zlib")
+        assert package_is_installed(prefix, "zlib")