Match logging

src/pip/_internal/resolution/resolvelib/factory.py

@@ -1,4 +1,5 @@
 import collections
+import logging
 
 from pip._vendor import six
 from pip._vendor.packaging.utils import canonicalize_name
@@ -50,6 +51,9 @@ if MYPY_CHECK_RUNNING:
     VersionCandidates = Dict[_BaseVersion, Candidate]
 
 
+logger = logging.getLogger(__name__)
+
+
 class Factory(object):
     def __init__(
         self,
@@ -196,6 +200,10 @@ class Factory(object):
         # type: (...) -> Optional[Requirement]
         ireq = self._make_install_req_from_spec(specifier, comes_from)
         if not ireq.match_markers(requested_extras):
+            logger.info(
+                "Ignoring %s: markers '%s' don't match your environment",
+                ireq.name, ireq.markers,
+            )
             return None
         return self.make_requirement_from_install_req(ireq)