Initial support for build.build-requires injection

Author: LecrisUT

Diff for: README.md

@@ -281,6 +281,10 @@ build.targets = []
 # Verbose printout when building.
 build.verbose = false
 
+# Additional ``build-system.requires``. Intended to be used in combination with
+# ``overrides``.
+build.build-requires = []
+
 # The components to install. If empty, all default components are installed.
 install.components = []
 

Diff for: src/scikit_build_core/builder/get_requires.py

@@ -140,6 +140,8 @@ def dynamic_metadata(self) -> Generator[str, None, None]:
         if self.settings.fail:
             return
 
+        yield from self.settings.build.build_requires
+
         for dynamic_metadata in self.settings.metadata.values():
             if "provider" in dynamic_metadata:
                 config = dynamic_metadata.copy()

Diff for: src/scikit_build_core/resources/scikit-build.schema.json

@@ -299,6 +299,13 @@
           "type": "boolean",
           "default": false,
           "description": "Verbose printout when building."
+        },
+        "build-requires": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "description": "Additional ``build-system.requires``. Intended to be used in combination with ``overrides``."
         }
       }
     },
@@ -560,6 +567,9 @@
                   },
                   "targets": {
                     "$ref": "#/$defs/inherit"
+                  },
+                  "build-requires": {
+                    "$ref": "#/$defs/inherit"
                   }
                 }
               },

Diff for: src/scikit_build_core/settings/skbuild_model.py

@@ -277,6 +277,12 @@ class BuildSettings:
     Verbose printout when building.
     """
 
+    build_requires: List[str] = dataclasses.field(default_factory=list)
+    """
+    Additional ``build-system.requires``. Intended to be used in combination
+    with ``overrides``.
+    """
+
 
 @dataclasses.dataclass
 class InstallSettings:

Diff for: tests/packages/dynamic_metadata/build_requires_project.toml

@@ -0,0 +1,13 @@
+[build-system]
+requires = ["scikit-build-core"]
+build-backend = "scikit_build_core.build"
+
+[project]
+name = "more_build_requires"
+
+[tool.scikit-build.build]
+build-requires = ["foo"]
+
+[[tool.scikit-build.overrides]]
+if.env.LOCAL_FOO = true
+build.build-requires = ["foo @ {root:uri}/foo"]

Diff for: tests/test_dynamic_metadata.py

@@ -7,7 +7,7 @@
 import types
 import zipfile
 from pathlib import Path
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 import pytest
 from packaging.version import Version
@@ -22,6 +22,9 @@
 
 from pathutils import contained
 
+if TYPE_CHECKING:
+    from scikit_build_core._compat.typing import Literal
+
 
 # these are mock plugins returning known results
 # it turns out to be easier to create EntryPoint objects pointing to real
@@ -345,3 +348,38 @@ def test_regex_remove(
     )
 
     assert version == ("1.2.3dev1" if dev else "1.2.3")
+
+
+@pytest.mark.usefixtures("package_dynamic_metadata")
+@pytest.mark.parametrize("override", [None, "env", "sdist"])
+def test_build_requires_field(override, monkeypatch) -> None:
+    shutil.copy("build_requires_project.toml", "pyproject.toml")
+
+    if override == "env":
+        monkeypatch.setenv("LOCAL_FOO", "True")
+    else:
+        monkeypatch.delenv("LOCAL_FOO", raising=False)
+
+    with Path("pyproject.toml").open("rb") as ft:
+        pyproject = tomllib.load(ft)
+    state: Literal["sdist", "metadata_wheel"] = (
+        "sdist" if override == "sdist" else "metadata_wheel"
+    )
+    settings_reader = SettingsReader(pyproject, {}, state=state)
+
+    settings_reader.validate_may_exit()
+
+    if override is None:
+        assert set(GetRequires().dynamic_metadata()) == {
+            "foo",
+        }
+    elif override == "env":
+        assert set(GetRequires().dynamic_metadata()) == {
+            # TODO: This should be resolved to actual path
+            "foo @ {root:uri}/foo",
+        }
+    elif override == "sdist":
+        assert set(GetRequires().dynamic_metadata()) == {
+            # TODO: Check if special handling should be done for sdist
+            "foo",
+        }