Support --build-constraint

src/pip/_internal/build_env.py

@@ -9,7 +9,7 @@
 import sys
 import textwrap
 from collections import OrderedDict
-from collections.abc import Iterable
+from collections.abc import Iterable, Sequence
 from contextlib import AbstractContextManager as ContextManager
 from contextlib import nullcontext
 from io import StringIO
@@ -277,12 +277,15 @@ def __init__(
         finder: PackageFinder,
         build_tracker: BuildTracker,
         wheel_cache: WheelCache,
+        build_constraints: Sequence[InstallRequirement] = (),
         resume_retries: int = 0,
         verbosity: int = 0,
     ) -> None:
         from pip._internal.operations.prepare import RequirementPreparer
 
-        self.finder = finder
+        self._finder = finder
+        self._build_constraints = build_constraints
+        self._wheel_cache = wheel_cache
         self._level = 0
 
         build_dir = TempDirectory(kind="build-env-install", globally_managed=True)
@@ -309,7 +312,6 @@ def __init__(
             lazy_wheel=False,
             legacy_resolver=False,
         )
-        self._wheel_cache = wheel_cache
 
     def install(
         self,
@@ -371,6 +373,8 @@ def _install_impl(self, requirements: Iterable[str], prefix: _Prefix) -> None:
         from pip._internal.wheel_builder import build
 
         ireqs = [install_req_from_line(req, user_supplied=True) for req in requirements]
+        ireqs.extend(self._build_constraints)
+
         resolver = self._make_resolver()
         resolved_set = resolver.resolve(ireqs, check_supported_wheels=True)
         self._preparer.prepare_linked_requirements_more(
@@ -413,7 +417,7 @@ def _make_resolver(self) -> BaseResolver:
             make_install_req=install_req_from_req_string,
             # Inherited state.
             preparer=self._preparer,
-            finder=self.finder,
+            finder=self._finder,
             wheel_cache=self._wheel_cache,
             # Hard-coded options (that should NOT be inherited).
             ignore_requires_python=False,

src/pip/_internal/cli/req_command.py

@@ -104,6 +104,31 @@ def wrapper(self: _CommandT, options: Values, args: list[str]) -> int:
     return wrapper
 
 
+def parse_constraint_files(
+    constraint_files: list[str],
+    finder: PackageFinder,
+    options: Values,
+    session: PipSession,
+) -> list[InstallRequirement]:
+    requirements = []
+    for filename in constraint_files:
+        for parsed_req in parse_requirements(
+            filename,
+            constraint=True,
+            finder=finder,
+            options=options,
+            session=session,
+        ):
+            req_to_add = install_req_from_parsed_requirement(
+                parsed_req,
+                isolated=options.isolated_mode,
+                user_supplied=False,
+            )
+            requirements.append(req_to_add)
+
+    return requirements
+
+
 class RequirementCommand(IndexGroupCommand):
     def __init__(self, *args: Any, **kw: Any) -> None:
         super().__init__(*args, **kw)
@@ -165,9 +190,13 @@ def make_requirement_preparer(
 
         env_installer: BuildEnvironmentInstaller
         if "inprocess-build-deps" in options.features_enabled:
+            build_constraint_reqs = parse_constraint_files(
+                build_constraints, finder, options, session
+            )
             env_installer = InprocessBuildEnvironmentInstaller(
                 finder=finder,
                 build_tracker=build_tracker,
+                build_constraints=build_constraint_reqs,
                 verbosity=verbosity,
                 resume_retries=options.resume_retries,
                 wheel_cache=WheelCache(options.cache_dir),
@@ -267,20 +296,10 @@ def get_requirements(
         requirements: list[InstallRequirement] = []
 
         if not should_ignore_regular_constraints(options):
-            for filename in options.constraints:
-                for parsed_req in parse_requirements(
-                    filename,
-                    constraint=True,
-                    finder=finder,
-                    options=options,
-                    session=session,
-                ):
-                    req_to_add = install_req_from_parsed_requirement(
-                        parsed_req,
-                        isolated=options.isolated_mode,
-                        user_supplied=False,
-                    )
-                    requirements.append(req_to_add)
+            constraints = parse_constraint_files(
+                options.constraints, finder, options, session
+            )
+            requirements.extend(constraints)
 
         for req in args:
             if not req.strip():