Try to find dependencies from unnormalized extras

When an unnormalized extra is requested, try to look up dependencies
with both its raw and normalized forms, to maintain compatibility when
an extra is both specified and requested in a non-standard form.

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

@@ -423,10 +423,11 @@ class ExtrasCandidate(Candidate):
     def __init__(
         self,
         base: BaseCandidate,
-        extras: FrozenSet[NormalizedName],
+        extras: FrozenSet[str],
     ) -> None:
         self.base = base
-        self.extras = extras
+        self.extras = frozenset(canonicalize_name(e) for e in extras)
+        self._unnormalized_extras = extras.difference(self.extras)
 
     def __str__(self) -> str:
         name, rest = str(self.base).split(" ", 1)
@@ -477,6 +478,44 @@ def is_editable(self) -> bool:
     def source_link(self) -> Optional[Link]:
         return self.base.source_link
 
+    def _warn_invalid_extras(
+        self,
+        requested: FrozenSet[str],
+        provided: FrozenSet[str],
+    ) -> None:
+        """Emit warnings for invalid extras being requested.
+
+        This emits a warning for each requested extra that is not in the
+        candidate's ``Provides-Extra`` list.
+        """
+        invalid_extras_to_warn = requested.difference(
+            provided,
+            # If an extra is requested in an unnormalized form, skip warning
+            # about the normalized form being missing.
+            (canonicalize_name(e) for e in self._unnormalized_extras),
+        )
+        if not invalid_extras_to_warn:
+            return
+        for extra in sorted(invalid_extras_to_warn):
+            logger.warning(
+                "%s %s does not provide the extra '%s'",
+                self.base.name,
+                self.version,
+                extra,
+            )
+
+    def _calculate_valid_requested_extras(self) -> FrozenSet[str]:
+        """Get a list of valid extras requested by this candidate.
+
+        The user (or upstream dependant) may have specified extras that the
+        candidate doesn't support. Any unsupported extras are dropped, and each
+        cause a warning to be logged here.
+        """
+        requested_extras = self.extras.union(self._unnormalized_extras)
+        provided_extras = frozenset(self.base.dist.iter_provided_extras())
+        self._warn_invalid_extras(requested_extras, provided_extras)
+        return requested_extras.intersection(provided_extras)
+
     def iter_dependencies(self, with_requires: bool) -> Iterable[Optional[Requirement]]:
         factory = self.base._factory
 
@@ -486,18 +525,7 @@ def iter_dependencies(self, with_requires: bool) -> Iterable[Optional[Requiremen
         if not with_requires:
             return
 
-        # The user may have specified extras that the candidate doesn't
-        # support. We ignore any unsupported extras here.
-        valid_extras = self.extras.intersection(self.base.dist.iter_provided_extras())
-        invalid_extras = self.extras.difference(self.base.dist.iter_provided_extras())
-        for extra in sorted(invalid_extras):
-            logger.warning(
-                "%s %s does not provide the extra '%s'",
-                self.base.name,
-                self.version,
-                extra,
-            )
-
+        valid_extras = self._calculate_valid_requested_extras()
         for r in self.base.dist.iter_dependencies(valid_extras):
             requirement = factory.make_requirement_from_spec(
                 str(r), self.base._ireq, valid_extras

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

@@ -140,9 +140,9 @@ def _fail_if_link_is_unsupported_wheel(self, link: Link) -> None:
     def _make_extras_candidate(
         self,
         base: BaseCandidate,
-        extras: FrozenSet[NormalizedName],
+        extras: FrozenSet[str],
     ) -> ExtrasCandidate:
-        cache_key = (id(base), extras)
+        cache_key = (id(base), frozenset(canonicalize_name(e) for e in extras))
         try:
             candidate = self._extras_candidate_cache[cache_key]
         except KeyError:
@@ -153,7 +153,7 @@ def _make_extras_candidate(
     def _make_candidate_from_dist(
         self,
         dist: BaseDistribution,
-        extras: FrozenSet[NormalizedName],
+        extras: FrozenSet[str],
         template: InstallRequirement,
     ) -> Candidate:
         try:
@@ -168,7 +168,7 @@ def _make_candidate_from_dist(
     def _make_candidate_from_link(
         self,
         link: Link,
-        extras: FrozenSet[NormalizedName],
+        extras: FrozenSet[str],
         template: InstallRequirement,
         name: Optional[NormalizedName],
         version: Optional[CandidateVersion],
@@ -246,12 +246,12 @@ def _iter_found_candidates(
         assert template.req, "Candidates found on index must be PEP 508"
         name = canonicalize_name(template.req.name)
 
-        extras: FrozenSet[NormalizedName] = frozenset()
+        extras: FrozenSet[str] = frozenset()
         for ireq in ireqs:
             assert ireq.req, "Candidates found on index must be PEP 508"
             specifier &= ireq.req.specifier
             hashes &= ireq.hashes(trust_internet=False)
-            extras |= frozenset(canonicalize_name(e) for e in ireq.extras)
+            extras |= frozenset(ireq.extras)
 
         def _get_installed_candidate() -> Optional[Candidate]:
             """Get the candidate for the currently-installed version."""
@@ -327,7 +327,7 @@ def is_pinned(specifier: SpecifierSet) -> bool:
     def _iter_explicit_candidates_from_base(
         self,
         base_requirements: Iterable[Requirement],
-        extras: FrozenSet[NormalizedName],
+        extras: FrozenSet[str],
     ) -> Iterator[Candidate]:
         """Produce explicit candidates from the base given an extra-ed package.
 
@@ -394,7 +394,7 @@ def find_candidates(
             explicit_candidates.update(
                 self._iter_explicit_candidates_from_base(
                     requirements.get(parsed_requirement.name, ()),
-                    frozenset(canonicalize_name(e) for e in parsed_requirement.extras),
+                    frozenset(parsed_requirement.extras),
                 ),
             )
 
@@ -454,7 +454,7 @@ def _make_requirement_from_install_req(
         self._fail_if_link_is_unsupported_wheel(ireq.link)
         cand = self._make_candidate_from_link(
             ireq.link,
-            extras=frozenset(canonicalize_name(e) for e in ireq.extras),
+            extras=frozenset(ireq.extras),
             template=ireq,
             name=canonicalize_name(ireq.name) if ireq.name else None,
             version=None,