Use pep517.Pep517HookCaller.subprocess_runner

Also, create a new utility function for showing a spinner when running
a subprocess.

Why: The subprocess_runner API was specifically added to make it
possible for pip to stop monkey-patching Pep517HookCaller, while still
maintaining its output style. The relevant monkeypatch will be removed
in a follow up commit.

src/pip/_internal/distributions/source/legacy.py

@@ -6,6 +6,7 @@ import logging
 from pip._internal.build_env import BuildEnvironment
 from pip._internal.distributions.base import AbstractDistribution
 from pip._internal.exceptions import InstallationError
+from pip._internal.utils.subprocess import run_with_spinner_message
 
 logger = logging.getLogger(__name__)
 
@@ -81,9 +82,13 @@ class SourceDistribution(AbstractDistribution):
         # This must be done in a second pass, as the pyproject.toml
         # dependencies must be installed before we can call the backend.
         with self.req.build_env:
-            # We need to have the env active when calling the hook.
-            self.req.spin_message = "Getting requirements to build wheel"
-            reqs = self.req.pep517_backend.get_requires_for_build_wheel()
+            runner = run_with_spinner_message(
+                "Getting requirements to build wheel"
+            )
+            backend = self.req.pep517_backend
+            with backend.subprocess_runner(runner):
+                reqs = backend.get_requires_for_build_wheel()
+
         conflicting, missing = self.req.build_env.check_requirements(reqs)
         if conflicting:
             _raise_conflicts("the backend dependencies", conflicting)

src/pip/_internal/req/req_install.py

@@ -49,7 +49,10 @@ from pip._internal.utils.misc import (
 )
 from pip._internal.utils.packaging import get_metadata
 from pip._internal.utils.setuptools_build import make_setuptools_shim_args
-from pip._internal.utils.subprocess import call_subprocess
+from pip._internal.utils.subprocess import (
+    call_subprocess,
+    run_with_spinner_message,
+)
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.ui import open_spinner
@@ -58,7 +61,7 @@ from pip._internal.vcs import vcs
 
 if MYPY_CHECK_RUNNING:
     from typing import (
-        Any, Dict, Iterable, List, Mapping, Optional, Sequence, Union,
+        Any, Dict, Iterable, List, Optional, Sequence, Union,
     )
     from pip._internal.build_env import BuildEnvironment
     from pip._internal.cache import WheelCache
@@ -622,11 +625,12 @@ class InstallRequirement(object):
             # Note that Pep517HookCaller implements a fallback for
             # prepare_metadata_for_build_wheel, so we don't have to
             # consider the possibility that this hook doesn't exist.
+            runner = run_with_spinner_message("Preparing wheel metadata")
             backend = self.pep517_backend
-            self.spin_message = "Preparing wheel metadata"
-            distinfo_dir = backend.prepare_metadata_for_build_wheel(
-                metadata_dir
-            )
+            with backend.subprocess_runner(runner):
+                distinfo_dir = backend.prepare_metadata_for_build_wheel(
+                    metadata_dir
+                )
 
         return os.path.join(metadata_dir, distinfo_dir)
 

src/pip/_internal/utils/subprocess.py

@@ -14,9 +14,12 @@ from pip._internal.utils.compat import console_to_str, str_to_display
 from pip._internal.utils.logging import subprocess_logger
 from pip._internal.utils.misc import HiddenText, path_to_display
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._internal.utils.ui import open_spinner
 
 if MYPY_CHECK_RUNNING:
-    from typing import Any, Iterable, List, Mapping, Optional, Text, Union
+    from typing import (
+        Any, Callable, Iterable, List, Mapping, Optional, Text, Union,
+    )
     from pip._internal.utils.ui import SpinnerInterface
 
     CommandArgs = List[Union[str, HiddenText]]
@@ -245,3 +248,28 @@ def call_subprocess(
             raise ValueError('Invalid value: on_returncode=%s' %
                              repr(on_returncode))
     return ''.join(all_output)
+
+
+def run_with_spinner_message(message):
+    # type: (str) -> Callable
+    """Provide a subprocess_runner that shows a spinner message.
+
+    Intended for use with for pep517's Pep517HookCaller. Thus, the runner has
+    an API that matches what's expected by Pep517HookCaller.subprocess_runner.
+    """
+
+    def runner(
+        cmd,  # type: List[str]
+        cwd=None,  # type: Optional[str]
+        extra_environ=None  # type: Optional[Mapping[str, Any]]
+    ):
+        # type: (...) -> None
+        with open_spinner(message) as spinner:
+            call_subprocess(
+                cmd,
+                cwd=cwd,
+                extra_environ=extra_environ,
+                spinner=spinner,
+            )
+
+    return runner

src/pip/_internal/wheel.py

@@ -44,6 +44,7 @@ from pip._internal.utils.subprocess import (
     LOG_DIVIDER,
     call_subprocess,
     format_command_args,
+    run_with_spinner_message,
 )
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
@@ -979,12 +980,17 @@ class WheelBuilder(object):
                          '--build-options is present' % (req.name,))
             return None
         try:
-            req.spin_message = 'Building wheel for %s (PEP 517)' % (req.name,)
             logger.debug('Destination directory: %s', tempd)
-            wheel_name = req.pep517_backend.build_wheel(
-                tempd,
-                metadata_directory=req.metadata_directory
+
+            runner = run_with_spinner_message(
+                'Building wheel for {} (PEP 517)'.format(req.name)
             )
+            backend = req.pep517_backend
+            with backend.subprocess_runner(runner):
+                wheel_name = backend.build_wheel(
+                    tempd,
+                    metadata_directory=req.metadata_directory,
+                )
             if python_tag:
                 # General PEP 517 backends don't necessarily support
                 # a "--python-tag" option, so we rename the wheel