Parse out extras when selecting from constraints

news/12018.bugfix.rst

@@ -0,0 +1,3 @@
+When looking for candidate provided via constraints, correctly parse and split
+the package name and extras from the user input, so the correct constraint can
+be picked based on the package name.

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

@@ -1,4 +1,3 @@
-import contextlib
 import functools
 import logging
 from typing import (
@@ -346,7 +345,8 @@ def _iter_explicit_candidates_from_base(
 
     def _iter_candidates_from_constraints(
         self,
-        identifier: str,
+        name: NormalizedName,
+        extras: FrozenSet[str],
         constraint: Constraint,
         template: InstallRequirement,
     ) -> Iterator[Candidate]:
@@ -359,9 +359,9 @@ def _iter_candidates_from_constraints(
             self._fail_if_link_is_unsupported_wheel(link)
             candidate = self._make_candidate_from_link(
                 link,
-                extras=frozenset(),
+                extras=extras,
                 template=install_req_from_link_and_ireq(link, template),
-                name=canonicalize_name(identifier),
+                name=name,
                 version=None,
             )
             if candidate:
@@ -385,15 +385,26 @@ def find_candidates(
             if ireq is not None:
                 ireqs.append(ireq)
 
+        try:
+            parsed_requirement = get_requirement(identifier)
+            assert (
+                not parsed_requirement.marker
+                and not list(parsed_requirement.specifier)
+                and not parsed_requirement.url
+            )
+        except InvalidRequirement:
+            name = identifier
+            extras: FrozenSet[str] = frozenset()
+        else:
+            name = parsed_requirement.name
+            extras = frozenset(parsed_requirement.extras)
+
         # If the current identifier contains extras, add explicit candidates
         # from entries from extra-less identifier.
-        with contextlib.suppress(InvalidRequirement):
-            parsed_requirement = get_requirement(identifier)
+        if extras:
+            reqs_for_name = requirements.get(name, ())
             explicit_candidates.update(
-                self._iter_explicit_candidates_from_base(
-                    requirements.get(parsed_requirement.name, ()),
-                    frozenset(parsed_requirement.extras),
-                ),
+                self._iter_explicit_candidates_from_base(reqs_for_name, extras),
             )
 
         # Add explicit candidates from constraints. We only do this if there are
@@ -404,7 +415,8 @@ def find_candidates(
             try:
                 explicit_candidates.update(
                     self._iter_candidates_from_constraints(
-                        identifier,
+                        canonicalize_name(name),
+                        extras,
                         constraint,
                         template=ireqs[0],
                     ),

tests/functional/test_install_extras.py

@@ -4,7 +4,12 @@
 
 import pytest
 
-from tests.lib import PipTestEnvironment, ResolverVariant, TestData
+from tests.lib import (
+    PipTestEnvironment,
+    ResolverVariant,
+    TestData,
+    create_basic_wheel_for_package,
+)
 
 
 @pytest.mark.network
@@ -223,3 +228,26 @@ def test_install_extra_merging(
     if not fails_on_legacy or resolver_variant == "2020-resolver":
         expected = f"Successfully installed pkga-0.1 simple-{simple_version}"
         assert expected in result.stdout
+
+
+def test_install_extra_from_url_constraint(script: PipTestEnvironment) -> None:
+    create_basic_wheel_for_package(script, name="fake", version="0")
+    pkg = create_basic_wheel_for_package(
+        script,
+        name="pkg",
+        version="2.0.1",
+        extras={"ext": ["fake"]},
+    )
+
+    constraints_path = script.scratch_path.joinpath("constraints.txt")
+    constraints_path.write_text(f"pkg @ {pkg.as_uri()}")
+    requirements_path = script.scratch_path.joinpath("requirements.txt")
+    requirements_path.write_text("pkg[ext]")
+    script.pip(
+        "install",
+        "--no-index",
+        "--no-cache",
+        f"--find-links={script.scratch_path}",
+        f"-r{requirements_path}",
+        f"-c{constraints_path}",
+    )