Repurpose backtracking hook

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

@@ -1,38 +1,18 @@
-from collections import defaultdict
 from logging import getLogger
-from typing import Any, DefaultDict
+from typing import Any
 
 from pip._vendor.resolvelib.reporters import BaseReporter
+from pip._vendor.resolvelib.resolvers import Criterion
 
 from .base import Candidate, Requirement
 
 logger = getLogger(__name__)
 
 
 class PipReporter(BaseReporter):
-    def __init__(self) -> None:
-        self.backtracks_by_package: DefaultDict[str, int] = defaultdict(int)
-
-        self._messages_at_backtrack = {
-            1: (
-                "pip is looking at multiple versions of {package_name} to "
-                "determine which version is compatible with other "
-                "requirements. This could take a while."
-            ),
-            8: (
-                "pip is looking at multiple versions of {package_name} to "
-                "determine which version is compatible with other "
-                "requirements. This could take a while."
-            ),
-            13: (
-                "This is taking longer than usual. You might need to provide "
-                "the dependency resolver with stricter constraints to reduce "
-                "runtime. See https://pip.pypa.io/warnings/backtracking for "
-                "guidance. If you want to abort this run, press Ctrl + C."
-            ),
-        }
-
-    def discarding_conflicted_criterion(self, criterion, candidate) -> None:
+    def backtracking(
+        self, criterion: Criterion[Any, Any, Any], candidate: Candidate
+    ) -> None:
         msg = "Will try a different candidate, due to conflict:"
         for req_info in criterion.information:
             req, parent = req_info.requirement, req_info.parent
@@ -43,17 +23,8 @@ def discarding_conflicted_criterion(self, criterion, candidate) -> None:
             else:
                 msg += "The user requested "
             msg += req.format_for_error()
-        logger.info(msg)
-
-    def backtracking(self, candidate: Candidate) -> None:
-        self.backtracks_by_package[candidate.name] += 1
-
-        count = self.backtracks_by_package[candidate.name]
-        if count not in self._messages_at_backtrack:
-            return
 
-        message = self._messages_at_backtrack[count]
-        logger.info("INFO: %s", message.format(package_name=candidate.name))
+        logger.info("INFO: %s", msg)
 
 
 class PipDebuggingReporter(BaseReporter):
@@ -74,7 +45,9 @@ def ending(self, state: Any) -> None:
     def adding_requirement(self, requirement: Requirement, parent: Candidate) -> None:
         logger.info("Reporter.adding_requirement(%r, %r)", requirement, parent)
 
-    def backtracking(self, candidate: Candidate) -> None:
+    def backtracking(
+        self, criterion: Criterion[Any, Any, Any], candidate: Candidate
+    ) -> None:
         logger.info("Reporter.backtracking(%r)", candidate)
 
     def pinning(self, candidate: Candidate) -> None:

src/pip/_vendor/resolvelib/reporters.py

@@ -30,16 +30,13 @@ def adding_requirement(self, requirement, parent):
             requirements passed in from ``Resolver.resolve()``.
         """
 
-    def discarding_conflicted_criterion(self, criterion, candidate):
-        """Called when discarding conflicted requirements."""
-
     def resolving_conflicts(self, causes):
         """Called when starting to attempt requirement conflict resolution.
 
         :param causes: The information on the collision that caused the backtracking.
         """
 
-    def backtracking(self, candidate):
+    def backtracking(self, criterion, candidate):
         """Called when rejecting a candidate during backtracking."""
 
     def pinning(self, candidate):

src/pip/_vendor/resolvelib/reporters.pyi

@@ -6,6 +6,6 @@ class BaseReporter:
     def ending_round(self, index: int, state: Any) -> Any: ...
     def ending(self, state: Any) -> Any: ...
     def adding_requirement(self, requirement: Any, parent: Any) -> Any: ...
-    def backtracking(self, candidate: Any) -> Any: ...
+    def backtracking(self, criterion: Any, candidate: Any) -> Any: ...
     def resolving_conflicts(self, causes: Any) -> Any: ...
     def pinning(self, candidate: Any) -> Any: ...

src/pip/_vendor/resolvelib/resolvers.py

@@ -212,7 +212,7 @@ def _attempt_to_pin_criterion(self, name):
             try:
                 criteria = self._get_updated_criteria(candidate)
             except RequirementsConflicted as e:
-                self._r.discarding_conflicted_criterion(e.criterion, candidate)
+                self._r.backtracking(e.criterion, candidate)
                 causes.append(e.criterion)
                 continue
 
@@ -282,8 +282,6 @@ def _backtrack(self):
             # Also mark the newly known incompatibility.
             incompatibilities_from_broken.append((name, [candidate]))
 
-            self._r.backtracking(candidate=candidate)
-
             # Create a new state from the last known-to-work one, and apply
             # the previously gathered incompatibility information.
             def _patch_criteria():