Merge pull request #13570 from ShubhamNagure/fix-constraint-reporting-13545

Fix constraint reporting in dependency conflict resolution logs #13545

Author: notatallshaw

news/13545.bugfix.rst

@@ -0,0 +1 @@
+Include relevant user-supplied constraints in logs when reporting dependency conflicts.

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

@@ -100,6 +100,15 @@ def __init__(
         self._upgrade_strategy = upgrade_strategy
         self._user_requested = user_requested
 
+    @property
+    def constraints(self) -> dict[str, Constraint]:
+        """Public view of user-specified constraints.
+
+        Exposes the provider's constraints mapping without encouraging
+        external callers to reach into private attributes.
+        """
+        return self._constraints
+
     def identify(self, requirement_or_candidate: Requirement | Candidate) -> str:
         return requirement_or_candidate.name
 

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

@@ -1,19 +1,21 @@
 from __future__ import annotations
 
 from collections import defaultdict
+from collections.abc import Mapping
 from logging import getLogger
 from typing import Any
 
 from pip._vendor.resolvelib.reporters import BaseReporter
 
-from .base import Candidate, Requirement
+from .base import Candidate, Constraint, Requirement
 
 logger = getLogger(__name__)
 
 
 class PipReporter(BaseReporter[Requirement, Candidate, str]):
-    def __init__(self) -> None:
+    def __init__(self, constraints: Mapping[str, Constraint] | None = None) -> None:
         self.reject_count_by_package: defaultdict[str, int] = defaultdict(int)
+        self._constraints = constraints or {}
 
         self._messages_at_reject_count = {
             1: (
@@ -35,25 +37,36 @@ def __init__(self) -> None:
         }
 
     def rejecting_candidate(self, criterion: Any, candidate: Candidate) -> None:
+        """Report a candidate being rejected.
+
+        Logs both the rejection count message (if applicable) and details about
+        the requirements and constraints that caused the rejection.
+        """
         self.reject_count_by_package[candidate.name] += 1
 
         count = self.reject_count_by_package[candidate.name]
-        if count not in self._messages_at_reject_count:
-            return
-
-        message = self._messages_at_reject_count[count]
-        logger.info("INFO: %s", message.format(package_name=candidate.name))
+        if count in self._messages_at_reject_count:
+            message = self._messages_at_reject_count[count]
+            logger.info("INFO: %s", message.format(package_name=candidate.name))
 
         msg = "Will try a different candidate, due to conflict:"
         for req_info in criterion.information:
             req, parent = req_info.requirement, req_info.parent
-            # Inspired by Factory.get_installation_error
             msg += "\n    "
             if parent:
                 msg += f"{parent.name} {parent.version} depends on "
             else:
                 msg += "The user requested "
             msg += req.format_for_error()
+
+        # Add any relevant constraints
+        if self._constraints:
+            name = candidate.name
+            constraint = self._constraints.get(name)
+            if constraint and constraint.specifier:
+                constraint_text = f"{name}{constraint.specifier}"
+                msg += f"\n    The user requested (constraint) {constraint_text}"
+
         logger.debug(msg)
 
 

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

@@ -87,7 +87,8 @@ def resolve(
         if "PIP_RESOLVER_DEBUG" in os.environ:
             reporter: BaseReporter[Requirement, Candidate, str] = PipDebuggingReporter()
         else:
-            reporter = PipReporter()
+            reporter = PipReporter(constraints=provider.constraints)
+
         resolver: RLResolver[Requirement, Candidate, str] = RLResolver(
             provider,
             reporter,