Abort immediately on metadata generation failure instead of backtracking

This behaviour is more forgiving when a source distribution cannot be
installed (eg: due to missing build dependencies or platform
incompatibility) and favours early eager failures instead of trying to
ensure that a package is installed regardless of the amount of effort it
takes.

Author: pradyunsg

news/10655.bugfix.rst

@@ -0,0 +1,4 @@
+Stop backtracking on build failures, by instead surfacing them to the
+user and failing immediately. This behaviour is more forgiving when
+a package cannot be built due to missing build dependencies or platform
+incompatibility.

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

@@ -27,7 +27,6 @@
 from pip._internal.exceptions import (
     DistributionNotFound,
     InstallationError,
-    InstallationSubprocessError,
     MetadataInconsistent,
     UnsupportedPythonVersion,
     UnsupportedWheel,
@@ -190,7 +189,7 @@ def _make_candidate_from_link(
                         name=name,
                         version=version,
                     )
-                except (InstallationSubprocessError, MetadataInconsistent) as e:
+                except MetadataInconsistent as e:
                     logger.warning("Discarding %s. %s", link, e)
                     self._build_failures[link] = e
                     return None
@@ -205,7 +204,7 @@ def _make_candidate_from_link(
                         name=name,
                         version=version,
                     )
-                except (InstallationSubprocessError, MetadataInconsistent) as e:
+                except MetadataInconsistent as e:
                     logger.warning("Discarding %s. %s", link, e)
                     self._build_failures[link] = e
                     return None

tests/functional/test_new_resolver.py

@@ -2308,3 +2308,22 @@ def test_new_resolver_respect_user_requested_if_extra_is_installed(
         "pkg2",
     )
     script.assert_installed(pkg3="1.0", pkg2="2.0", pkg1="1.0")
+
+
+def test_new_resolver_do_not_backtrack_on_build_failure(
+    script: PipTestEnvironment,
+) -> None:
+    create_basic_sdist_for_package(script, "pkg1", "2.0", fails_egg_info=True)
+    create_basic_wheel_for_package(script, "pkg1", "1.0")
+
+    result = script.pip(
+        "install",
+        "--no-cache-dir",
+        "--no-index",
+        "--find-links",
+        script.scratch_path,
+        "pkg1",
+        expect_error=True,
+    )
+
+    assert "egg_info" in result.stderr

tests/lib/__init__.py

@@ -1181,22 +1181,36 @@ def create_basic_sdist_for_package(
     name: str,
     version: str,
     extra_files: Optional[Dict[str, str]] = None,
+    *,
+    fails_egg_info: bool = False,
+    fails_bdist_wheel: bool = False,
 ) -> Path:
     files = {
-        "setup.py": """
+        "setup.py": f"""\
+            import sys
             from setuptools import find_packages, setup
+
+            fails_bdist_wheel = {fails_bdist_wheel!r}
+            fails_egg_info = {fails_egg_info!r}
+
+            if fails_egg_info and "egg_info" in sys.argv:
+                raise Exception("Simulated failure for generating metadata.")
+
+            if fails_bdist_wheel and "bdist_wheel" in sys.argv:
+                raise Exception("Simulated failure for building a wheel.")
+
             setup(name={name!r}, version={version!r})
         """,
     }
 
     # Some useful shorthands
-    archive_name = "{name}-{version}.tar.gz".format(name=name, version=version)
+    archive_name = f"{name}-{version}.tar.gz"
 
     # Replace key-values with formatted values
     for key, value in list(files.items()):
         del files[key]
         key = key.format(name=name)
-        files[key] = textwrap.dedent(value).format(name=name, version=version).strip()
+        files[key] = textwrap.dedent(value)
 
     # Add new files after formatting
     if extra_files: