fix: fallthrough empty manylinux images

cibuildwheel/__main__.py

@@ -291,9 +291,9 @@ def main() -> None:
         for build_platform in MANYLINUX_ARCHS:
             pinned_images = all_pinned_docker_images[build_platform]
 
-            config_value = options(f"manylinux-{build_platform}-image")
+            config_value = options(f"manylinux-{build_platform}-image", ignore_empty=True)
 
-            if config_value is None:
+            if not config_value:
                 # default to manylinux2010 if it's available, otherwise manylinux2014
                 image = pinned_images.get("manylinux2010") or pinned_images.get("manylinux2014")
             elif config_value in pinned_images:

cibuildwheel/options.py

@@ -19,15 +19,26 @@ class ConfigOptionError(KeyError):
     pass
 
 
-def _dig_first(*pairs: Tuple[Mapping[str, Any], str]) -> Setting:
+def _dig_first(*pairs: Tuple[Mapping[str, Any], str], ignore_empty: bool = False) -> Setting:
     """
     Return the first dict item that matches from pairs of dicts and keys.
     Final result is will throw a KeyError if missing.
 
     _dig_first((dict1, "key1"), (dict2, "key2"), ...)
     """
     (dict_like, key), *others = pairs
-    return dict_like.get(key, _dig_first(*others)) if others else dict_like[key]
+    if ignore_empty:
+        return (
+            (dict_like.get(key, "") or _dig_first(*others, ignore_empty=ignore_empty))
+            if others
+            else dict_like[key]
+        )
+    else:
+        return (
+            dict_like.get(key, _dig_first(*others, ignore_empty=ignore_empty))
+            if others
+            else dict_like[key]
+        )
 
 
 class ConfigOptions:
@@ -62,7 +73,7 @@ def __init__(
         defaults_path = resources_dir / "defaults.toml"
         self.default_options, self.default_platform_options = self._load_file(defaults_path)
 
-        # load the project config file
+        # Load the project config file
         config_options: Dict[str, Any] = {}
         config_platform_options: Dict[str, Any] = {}
 
@@ -75,7 +86,7 @@ def __init__(
             if pyproject_toml_path.exists():
                 config_options, config_platform_options = self._load_file(pyproject_toml_path)
 
-        # validate project config
+        # Validate project config
         for option_name in config_options:
             if not self._is_valid_global_option(option_name):
                 raise ConfigOptionError(f'Option "{option_name}" not supported in a config file')
@@ -129,14 +140,16 @@ def __call__(
         env_plat: bool = True,
         sep: Optional[str] = None,
         table: Optional[TableFmt] = None,
+        ignore_empty: bool = False,
     ) -> str:
         """
         Get and return the value for the named option from environment,
         configuration file, or the default. If env_plat is False, then don't
         accept platform versions of the environment variable. If this is an
         array it will be merged with "sep" before returning. If it is a table,
         it will be formatted with "table['item']" using {k} and {v} and merged
-        with "table['sep']".
+        with "table['sep']". Empty variables will not override if empty_invalid
+        is True.
         """
 
         if name not in self.default_options and name not in self.default_platform_options:
@@ -155,6 +168,7 @@ def __call__(
             (self.config_options, name),
             (self.default_platform_options, name),
             (self.default_options, name),
+            ignore_empty=ignore_empty,
         )
 
         if isinstance(result, dict):

docs/options.md

@@ -797,8 +797,7 @@ The available options are:
 Set an alternative Docker image to be used for building [manylinux](https://github.com/pypa/manylinux) wheels. cibuildwheel will then pull these instead of the default images, [`quay.io/pypa/manylinux2010_x86_64`](https://quay.io/pypa/manylinux2010_x86_64), [`quay.io/pypa/manylinux2010_i686`](https://quay.io/pypa/manylinux2010_i686), [`quay.io/pypa/manylinux2010_x86_64`](https://quay.io/pypa/manylinux2010_x86_64), [`quay.io/pypa/manylinux2014_aarch64`](https://quay.io/pypa/manylinux2014_aarch64), [`quay.io/pypa/manylinux2014_ppc64le`](https://quay.io/pypa/manylinux2014_ppc64le), and [`quay.io/pypa/manylinux2014_s390x`](https://quay.io/pypa/manylinux2010_s390x).
 
 The value of this option can either be set to `manylinux1`, `manylinux2010`, `manylinux2014` or `manylinux_2_24` to use a pinned version of the [official manylinux images](https://github.com/pypa/manylinux). Alternatively, set these options to any other valid Docker image name. For PyPy, the `manylinux1` image is not available. For architectures other
-than x86 (x86\_64 and i686) `manylinux2014` or `manylinux_2_24` must be used, because the first version of the manylinux specification that supports additional architectures is `manylinux2014`.
-
+than x86 (x86\_64 and i686) `manylinux2014` or `manylinux_2_24` must be used, because the first version of the manylinux specification that supports additional architectures is `manylinux2014`. If this option is blank, it will fall though to the next available definition (environment variable -> pyproject.toml -> default).
 
 If setting a custom Docker image, you'll need to make sure it can be used in the same way as the official, default Docker images: all necessary Python and pip versions need to be present in `/opt/python/`, and the auditwheel tool needs to be present for cibuildwheel to work. Apart from that, the architecture and relevant shared system libraries need to be compatible to the relevant standard to produce valid manylinux1/manylinux2010/manylinux2014/manylinux_2_24 wheels (see [pypa/manylinux on GitHub](https://github.com/pypa/manylinux), [PEP 513](https://www.python.org/dev/peps/pep-0513/), [PEP 571](https://www.python.org/dev/peps/pep-0571/), [PEP 599](https://www.python.org/dev/peps/pep-0599/) and [PEP 600](https://www.python.org/dev/peps/pep-0600/) for more details).
 

unit_test/options_toml_test.py

@@ -1,6 +1,6 @@
 import pytest
 
-from cibuildwheel.options import ConfigOptionError, ConfigOptions
+from cibuildwheel.options import ConfigOptionError, ConfigOptions, _dig_first
 
 PYPROJECT_1 = """
 [tool.cibuildwheel]
@@ -181,10 +181,68 @@ def test_disallowed_a(tmp_path):
     tmp_path.joinpath("pyproject.toml").write_text(
         """
 [tool.cibuildwheel.windows]
-manylinux-x64_86-image = "manylinux1"
+manylinux-x86_64-image = "manylinux1"
 """
     )
-    disallow = {"windows": {"manylinux-x64_86-image"}}
+    disallow = {"windows": {"manylinux-x86_64-image"}}
     ConfigOptions(tmp_path, platform="linux", disallow=disallow)
     with pytest.raises(ConfigOptionError):
         ConfigOptions(tmp_path, platform="windows", disallow=disallow)
+
+
+def test_environment_override_empty(tmp_path, monkeypatch):
+    tmp_path.joinpath("pyproject.toml").write_text(
+        """
+[tool.cibuildwheel]
+manylinux-i686-image = "manylinux1"
+manylinux-x86_64-image = ""
+"""
+    )
+
+    monkeypatch.setenv("CIBW_MANYLINUX_I686_IMAGE", "")
+    monkeypatch.setenv("CIBW_MANYLINUX_AARCH64_IMAGE", "manylinux1")
+
+    options = ConfigOptions(tmp_path, platform="linux")
+
+    assert options("manylinux-x86_64-image") == ""
+    assert options("manylinux-i686-image") == ""
+    assert options("manylinux-aarch64-image") == "manylinux1"
+
+    assert options("manylinux-x86_64-image", ignore_empty=True) == "manylinux2010"
+    assert options("manylinux-i686-image", ignore_empty=True) == "manylinux1"
+    assert options("manylinux-aarch64-image", ignore_empty=True) == "manylinux1"
+
+
+@pytest.mark.parametrize("ignore_empty", (True, False))
+def test_dig_first(ignore_empty):
+    d1 = {"random": "thing"}
+    d2 = {"this": "that", "empty": ""}
+    d3 = {"other": "hi"}
+    d4 = {"this": "d4", "empty": "not"}
+
+    answer = _dig_first(
+        (d1, "empty"),
+        (d2, "empty"),
+        (d3, "empty"),
+        (d4, "empty"),
+        ignore_empty=ignore_empty,
+    )
+    assert answer == ("not" if ignore_empty else "")
+
+    answer = _dig_first(
+        (d1, "this"),
+        (d2, "this"),
+        (d3, "this"),
+        (d4, "this"),
+        ignore_empty=ignore_empty,
+    )
+    assert answer == "that"
+
+    with pytest.raises(KeyError):
+        _dig_first(
+            (d1, "this"),
+            (d2, "other"),
+            (d3, "this"),
+            (d4, "other"),
+            ignore_empty=ignore_empty,
+        )