feat: if failed (retry) (#820)

One of the steps for #112.

---------

Signed-off-by: Henry Schreiner <[email protected]>

docs/overrides.md

@@ -132,6 +132,19 @@ SDist.
 This will be true if the `PKG-INFO` file exists, that is, if this is coming
 from an SDist. Takes a bool.
 
+### `failed` (bool)
+
+This override is a bit special. If a build fails, scikit-build-core will check
+to see if there'a a matching `failed = true` override. If there is, the the build will
+be retried once with the new settings. This can be used to build a pure-Python fallback
+if a build fails, for example:
+
+```toml
+[[tool.scikit-build.overrides]]
+if.failed = true
+wheel.cmake = false
+```
+
 ## Any matching condition
 
 If you use `if.any` instead of `if`, then the override is true if any one of the

src/scikit_build_core/build/_init.py

@@ -15,9 +15,9 @@ def __dir__() -> list[str]:
 @functools.lru_cache(1)
 def setup_logging(log_level: str) -> None:
     level_value = LEVEL_VALUE[log_level]
+    logger.setLevel(level_value)
 
     ch = logging.StreamHandler()
-    ch.setLevel(level_value)
     # create formatter and add it to the handlers
     formatter = logging.Formatter(
         "%(asctime)s - %(name)s - %(levelname)s - %(message)s"

src/scikit_build_core/build/wheel.py

@@ -7,19 +7,20 @@
 import sysconfig
 import tempfile
 from pathlib import Path
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 from packaging.requirements import Requirement
 from packaging.utils import canonicalize_name
 
 from .. import __version__
 from .._compat import tomllib
 from .._compat.typing import Literal, assert_never
-from .._logging import logger, rich_print
+from .._logging import LEVEL_VALUE, logger, rich_print
 from .._shutil import fix_win_37_all_permissions
 from ..builder.builder import Builder, archs_to_tags, get_archs
 from ..builder.wheel_tag import WheelTag
 from ..cmake import CMake, CMaker
+from ..errors import FailedLiveProcessError
 from ..settings.skbuild_read_settings import SettingsReader
 from ._editable import editable_redirect, libdir_to_installed, mapping_to_modules
 from ._init import setup_logging
@@ -123,6 +124,7 @@ def _build_wheel_impl(
 ) -> WheelImplReturn:
     """
     Build a wheel or just prepare metadata (if wheel dir is None). Can be editable.
+    Handles one retry attempt if "failed" override present.
     """
     state: Literal["sdist", "wheel", "editable", "metadata_wheel", "metadata_editable"]
     if exit_after_config:
@@ -136,9 +138,10 @@ def _build_wheel_impl(
     with pyproject_path.open("rb") as ft:
         pyproject = tomllib.load(ft)
 
-    settings_reader = SettingsReader(pyproject, config_settings or {}, state=state)
-    settings = settings_reader.settings
-    setup_logging(settings.logging.level)
+    settings_reader = SettingsReader(
+        pyproject, config_settings or {}, state=state, retry=False
+    )
+    setup_logging(settings_reader.settings.logging.level)
 
     settings_reader.validate_may_exit()
 
@@ -156,6 +159,56 @@ def _build_wheel_impl(
             "ninja should not be in build-system.requires - scikit-build-core will inject it as needed"
         )
 
+    try:
+        return _build_wheel_impl_impl(
+            wheel_directory,
+            metadata_directory,
+            exit_after_config=exit_after_config,
+            editable=editable,
+            state=state,
+            settings=settings_reader.settings,
+            pyproject=pyproject,
+        )
+    except FailedLiveProcessError as err:
+        settings_reader = SettingsReader(
+            pyproject, config_settings or {}, state=state, retry=True
+        )
+        if "failed" not in settings_reader.overrides:
+            raise
+
+        rich_print(
+            f"\n[yellow bold]*** {' '.join(err.args)} - retrying due to override..."
+        )
+
+        logger.setLevel(LEVEL_VALUE[settings_reader.settings.logging.level])
+
+        settings_reader.validate_may_exit()
+
+        return _build_wheel_impl_impl(
+            wheel_directory,
+            metadata_directory,
+            exit_after_config=exit_after_config,
+            editable=editable,
+            state=state,
+            settings=settings_reader.settings,
+            pyproject=pyproject,
+        )
+
+
+def _build_wheel_impl_impl(
+    wheel_directory: str | None,
+    metadata_directory: str | None,
+    *,
+    exit_after_config: bool = False,
+    editable: bool,
+    state: Literal["sdist", "wheel", "editable", "metadata_wheel", "metadata_editable"],
+    settings: ScikitBuildSettings,
+    pyproject: dict[str, Any],
+) -> WheelImplReturn:
+    """
+    Build a wheel or just prepare metadata (if wheel dir is None). Can be editable.
+    """
+
     metadata = get_standard_metadata(pyproject, settings)
 
     if metadata.version is None:

src/scikit_build_core/resources/scikit-build.schema.json

@@ -628,6 +628,10 @@
           "type": "boolean",
           "description": "Whether the build is from an sdist."
         },
+        "failed": {
+          "type": "boolean",
+          "description": "Matches if the build fails. A build will be retried if there is at least one matching override with this set to true."
+        },
         "env": {
           "type": "object",
           "patternProperties": {