fix: respect constraints when building with pip (#1818)

When building a project that has a `pyproject.toml`, constraints
are not respected when building with the `pip` frontend.

This commit fixes this by using the same tricks as for the `build` frontend.

Author: mayeut

cibuildwheel/macos.py

@@ -381,6 +381,18 @@ def build(options: Options, tmp_path: Path) -> None:
                 )
                 extra_flags += build_frontend.args
 
+                build_env = env.copy()
+                build_env["VIRTUALENV_PIP"] = get_pip_version(env)
+                if build_options.dependency_constraints:
+                    constraint_path = build_options.dependency_constraints.get_for_python_version(
+                        config.version
+                    )
+                    user_constraints = build_env.get("PIP_CONSTRAINT")
+                    our_constraints = constraint_path.as_uri()
+                    build_env["PIP_CONSTRAINT"] = " ".join(
+                        c for c in [user_constraints, our_constraints] if c
+                    )
+
                 if build_frontend.name == "pip":
                     extra_flags += get_build_verbosity_extra_flags(build_options.build_verbosity)
                     # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
@@ -394,25 +406,12 @@ def build(options: Options, tmp_path: Path) -> None:
                         f"--wheel-dir={built_wheel_dir}",
                         "--no-deps",
                         *extra_flags,
-                        env=env,
+                        env=build_env,
                     )
                 elif build_frontend.name == "build":
                     if not 0 <= build_options.build_verbosity < 2:
                         msg = f"build_verbosity {build_options.build_verbosity} is not supported for build frontend. Ignoring."
                         log.warning(msg)
-                    build_env = env.copy()
-                    if build_options.dependency_constraints:
-                        constraint_path = (
-                            build_options.dependency_constraints.get_for_python_version(
-                                config.version
-                            )
-                        )
-                        user_constraints = build_env.get("PIP_CONSTRAINT")
-                        our_constraints = constraint_path.as_uri()
-                        build_env["PIP_CONSTRAINT"] = " ".join(
-                            c for c in [user_constraints, our_constraints] if c
-                        )
-                    build_env["VIRTUALENV_PIP"] = get_pip_version(env)
                     call(
                         "python",
                         "-m",

cibuildwheel/windows.py

@@ -407,6 +407,28 @@ def build(options: Options, tmp_path: Path) -> None:
                 )
                 extra_flags += build_frontend.args
 
+                build_env = env.copy()
+                build_env["VIRTUALENV_PIP"] = get_pip_version(env)
+                if build_options.dependency_constraints:
+                    constraints_path = build_options.dependency_constraints.get_for_python_version(
+                        config.version
+                    )
+                    # Bug in pip <= 21.1.3 - we can't have a space in the
+                    # constraints file, and pip doesn't support drive letters
+                    # in uhi.  After probably pip 21.2, we can use uri. For
+                    # now, use a temporary file.
+                    if " " in str(constraints_path):
+                        assert " " not in str(identifier_tmp_dir)
+                        tmp_file = identifier_tmp_dir / "constraints.txt"
+                        tmp_file.write_bytes(constraints_path.read_bytes())
+                        constraints_path = tmp_file
+
+                    our_constraints = str(constraints_path)
+                    user_constraints = build_env.get("PIP_CONSTRAINT")
+                    build_env["PIP_CONSTRAINT"] = " ".join(
+                        c for c in [our_constraints, user_constraints] if c
+                    )
+
                 if build_frontend.name == "pip":
                     extra_flags += get_build_verbosity_extra_flags(build_options.build_verbosity)
                     # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
@@ -420,46 +442,22 @@ def build(options: Options, tmp_path: Path) -> None:
                         f"--wheel-dir={built_wheel_dir}",
                         "--no-deps",
                         *extra_flags,
-                        env=env,
+                        env=build_env,
                     )
                 elif build_frontend.name == "build":
                     if not 0 <= build_options.build_verbosity < 2:
                         msg = f"build_verbosity {build_options.build_verbosity} is not supported for build frontend. Ignoring."
                         log.warning(msg)
-                    build_env = env.copy()
-                    if build_options.dependency_constraints:
-                        constraints_path = (
-                            build_options.dependency_constraints.get_for_python_version(
-                                config.version
-                            )
-                        )
-                        # Bug in pip <= 21.1.3 - we can't have a space in the
-                        # constraints file, and pip doesn't support drive letters
-                        # in uhi.  After probably pip 21.2, we can use uri. For
-                        # now, use a temporary file.
-                        if " " in str(constraints_path):
-                            assert " " not in str(identifier_tmp_dir)
-                            tmp_file = identifier_tmp_dir / "constraints.txt"
-                            tmp_file.write_bytes(constraints_path.read_bytes())
-                            constraints_path = tmp_file
-
-                        our_constraints = str(constraints_path)
-                        user_constraints = build_env.get("PIP_CONSTRAINT")
-                        build_env["PIP_CONSTRAINT"] = " ".join(
-                            c for c in [our_constraints, user_constraints] if c
-                        )
-
-                        build_env["VIRTUALENV_PIP"] = get_pip_version(env)
-                        call(
-                            "python",
-                            "-m",
-                            "build",
-                            build_options.package_dir,
-                            "--wheel",
-                            f"--outdir={built_wheel_dir}",
-                            *extra_flags,
-                            env=build_env,
-                        )
+                    call(
+                        "python",
+                        "-m",
+                        "build",
+                        build_options.package_dir,
+                        "--wheel",
+                        f"--outdir={built_wheel_dir}",
+                        *extra_flags,
+                        env=build_env,
+                    )
                 else:
                     assert_never(build_frontend)
 

test/test_dependency_versions.py

@@ -15,9 +15,10 @@
         r"""
         import subprocess
         import os
+        import sys
 
         versions_output_text = subprocess.check_output(
-            ['pip', 'freeze', '--all', '-qq'],
+            [sys.executable, '-m', 'pip', 'freeze', '--all', '-qq'],
             universal_newlines=True,
         )
         versions = versions_output_text.strip().splitlines()
@@ -36,6 +37,11 @@
     )
 )
 
+project_with_expected_version_checks.files["pyproject.toml"] = r"""
+[build-system]
+requires = ["setuptools", "pip"]
+build-backend = "setuptools.build_meta"
+"""
 
 VERSION_REGEX = r"([\w-]+)==([^\s]+)"
 
@@ -50,27 +56,16 @@ def get_versions_from_constraint_file(constraint_file):
 def test_pinned_versions(tmp_path, python_version, build_frontend_env):
     if utils.platform == "linux":
         pytest.skip("linux doesn't pin individual tool versions, it pins manylinux images instead")
+    if python_version == "3.6" and utils.platform == "macos" and platform.machine() == "arm64":
+        pytest.skip("macOS arm64 does not support Python 3.6")
 
     project_dir = tmp_path / "project"
     project_with_expected_version_checks.generate(project_dir)
 
+    version_no_dot = python_version.replace(".", "")
     build_environment = {}
-
-    if python_version == "3.6":
-        if utils.platform == "macos" and platform.machine() == "arm64":
-            pytest.skip("macOS arm64 does not support Python 3.6")
-        constraint_filename = "constraints-python36.txt"
-        build_pattern = "[cp]p36-*"
-    elif python_version == "3.7":
-        constraint_filename = "constraints-python37.txt"
-        build_pattern = "[cp]p37-*"
-    elif python_version == "3.8":
-        constraint_filename = "constraints-python38.txt"
-        build_pattern = "[cp]p38-*"
-    else:
-        constraint_filename = "constraints-python310.txt"
-        build_pattern = "[cp]p310-*"
-
+    build_pattern = f"[cp]p{version_no_dot}-*"
+    constraint_filename = f"constraints-python{version_no_dot}.txt"
     constraint_file = cibuildwheel.util.resources_dir / constraint_filename
     constraint_versions = get_versions_from_constraint_file(constraint_file)
 
@@ -89,21 +84,11 @@ def test_pinned_versions(tmp_path, python_version, build_frontend_env):
     )
 
     # also check that we got the right wheels
-    if python_version == "3.6":
-        expected_wheels = [
-            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp36" in w or "-pp36" in w
-        ]
-    elif python_version == "3.8":
-        expected_wheels = [
-            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp38" in w or "-pp38" in w
-        ]
-    elif python_version == "3.10":
-        expected_wheels = [
-            w for w in utils.expected_wheels("spam", "0.1.0") if "-cp310" in w or "-pp310" in w
-        ]
-    else:
-        msg = "unhandled python version"
-        raise ValueError(msg)
+    expected_wheels = [
+        w
+        for w in utils.expected_wheels("spam", "0.1.0")
+        if f"-cp{version_no_dot}" in w or f"-pp{version_no_dot}" in w
+    ]
 
     assert set(actual_wheels) == set(expected_wheels)