Read cmake.root entry_points and unify search path handling

Signed-off-by: Cristian Le <[email protected]>

README.md

@@ -312,6 +312,20 @@ messages.after-success = ""
 # paths.
 use-site-packages = true
 
+# Entry points to ignore. Any entry-point in `cmake.module`, `cmake.prefix`,
+# `cmake.root` with a key value matching a value in this list will be ignored
+# when building the search paths.
+ignore_entry_point = []
+
+# List of additional CMake module search paths. Populates `CMAKE_MODULE_PATH`.
+search.modules = []
+
+# List of additional CMake prefix search paths. Populates `CMAKE_PREFIX_PATH`.
+search.prefixes = []
+
+# Dict of package names and prefix paths. Populates `<Pkg>_ROOT`.
+search.roots = {}
+
 # List dynamic metadata fields and hook locations in this table.
 metadata = {}
 

src/scikit_build_core/builder/builder.py

@@ -97,6 +97,32 @@ def _sanitize_path(path: os.PathLike[str]) -> list[Path]:
     return [Path(os.fspath(path))]
 
 
+def _merge_search_paths(
+    entry_point_search_path: dict[str, list[Path]],
+    settings_val: list[str] | dict[str, str],
+    output: list[Path] | dict[str, list[Path]],
+) -> None:
+    if isinstance(settings_val, dict):
+        # if the settings and output search paths are dicts, just override them
+        # and update the output
+        assert isinstance(output, dict)
+        # No need to clone this because the search paths are not used anywhere else.
+        # Just renaming for readability
+        search_paths_dict = entry_point_search_path
+        for key, val in settings_val.items():
+            search_paths_dict[key] = [Path(val)]
+        output.update(search_paths_dict)
+        return
+    # Otherwise the settings and outputs are lists.
+    # We flatten out the dict into a list and append the settings values.
+    assert isinstance(output, list)
+    search_paths_list = [
+        path for ep_values in entry_point_search_path.values() for path in ep_values
+    ]
+    search_paths_list += map(Path, settings_val)
+    output.extend(search_paths_list)
+
+
 @dataclasses.dataclass
 class Builder:
     settings: ScikitBuildSettings
@@ -120,6 +146,23 @@ def get_cmake_args(self) -> list[str]:
     def get_generator(self, *args: str) -> str | None:
         return self.config.get_generator(*self.get_cmake_args(), *args)
 
+    def _get_entry_point_search_path(self, entry_point: str) -> dict[str, list[Path]]:
+        """Get the search path dict from the entry points"""
+        search_paths = {}
+        eps = metadata.entry_points(group=entry_point)
+        if eps:
+            logger.debug(
+                "Loading search paths {} from entry-points: {}", entry_point, len(eps)
+            )
+            for ep in eps:
+                if ep.name in self.settings.search.ignore_entry_point:
+                    logger.debug("Ignoring entry-point: {}", ep.name)
+                ep_value = _sanitize_path(resources.files(ep.load()))
+                logger.debug("{}: {} -> {}", ep.name, ep.value, ep_value)
+                if ep_value:
+                    search_paths[ep.name] = ep_value
+        return search_paths
+
     def configure(
         self,
         *,
@@ -136,16 +179,29 @@ def configure(
         }
 
         # Add any extra CMake modules
-        eps = metadata.entry_points(group="cmake.module")
-        self.config.module_dirs.extend(
-            p for ep in eps for p in _sanitize_path(resources.files(ep.load()))
+        _merge_search_paths(
+            self._get_entry_point_search_path("cmake.module"),
+            self.settings.search.modules,
+            self.config.module_dirs,
         )
+        logger.debug("cmake.modules: {}", self.config.module_dirs)
 
         # Add any extra CMake prefixes
-        eps = metadata.entry_points(group="cmake.prefix")
-        self.config.prefix_dirs.extend(
-            p for ep in eps for p in _sanitize_path(resources.files(ep.load()))
+        _merge_search_paths(
+            self._get_entry_point_search_path("cmake.prefix"),
+            self.settings.search.prefixes,
+            self.config.prefix_dirs,
+        )
+        logger.debug("cmake.prefix: {}", self.config.prefix_dirs)
+
+        # Add all CMake roots
+        # TODO: Check for unique uppercase names
+        _merge_search_paths(
+            self._get_entry_point_search_path("cmake.root"),
+            self.settings.search.roots,
+            self.config.prefix_roots,
         )
+        logger.debug("cmake.root: {}", self.config.prefix_roots)
 
         # Add site-packages to the prefix path for CMake
         site_packages = Path(sysconfig.get_path("purelib"))

src/scikit_build_core/cmake.py

@@ -79,6 +79,7 @@ class CMaker:
     build_type: str
     module_dirs: list[Path] = dataclasses.field(default_factory=list)
     prefix_dirs: list[Path] = dataclasses.field(default_factory=list)
+    prefix_roots: dict[str, list[Path]] = dataclasses.field(default_factory=dict)
     init_cache_file: Path = dataclasses.field(init=False, default=Path())
     env: dict[str, str] = dataclasses.field(init=False, default_factory=os.environ.copy)
     single_config: bool = not sysconfig.get_platform().startswith("win")
@@ -183,6 +184,17 @@ def init_cache(
                 )
                 f.write('set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE "BOTH" CACHE PATH "")\n')
 
+            if self.prefix_roots:
+                for pkg, path_list in self.prefix_roots.items():
+                    paths_str = ";".join(map(str, path_list)).replace("\\", "/")
+                    f.write(
+                        f'set({pkg}_ROOT [===[{paths_str}]===] CACHE PATH "" FORCE)\n'
+                    )
+                    # Available since CMake 3.27 with CMP0144
+                    f.write(
+                        f'set({pkg.upper()}_ROOT [===[{paths_str}]===] CACHE PATH "" FORCE)\n'
+                    )
+
         contents = self.init_cache_file.read_text(encoding="utf-8").strip()
         logger.debug(
             "{}:\n{}",

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

@@ -96,6 +96,36 @@
     "search": {
       "additionalProperties": false,
       "properties": {
+        "modules": {
+          "description": "List of additional CMake module search paths. Populates `CMAKE_MODULE_PATH`.",
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "prefixes": {
+          "description": "List of additional CMake prefix search paths. Populates `CMAKE_PREFIX_PATH`.",
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
+        "roots": {
+          "description": "Dict of package names and prefix paths. Populates `<Pkg>_ROOT`.",
+          "type": "object",
+          "patternProperties": {
+            ".+": {
+              "type": "string"
+            }
+          }
+        },
+        "ignore_entry_point": {
+          "description": "Entry points to ignore. Any entry-point in `cmake.module`, `cmake.prefix`, `cmake.root` with a key value matching a value in this list will be ignored when building the search paths.",
+          "type": "array",
+          "items": {
+            "type": "string"
+          }
+        },
         "use-site-packages": {
           "default": true,
           "description": "Add the install (or build isolation) site_packages folder to the CMake prefix paths.",
@@ -535,6 +565,21 @@
                   }
                 }
               },
+              "search": {
+                "type": "object",
+                "additionalProperties": false,
+                "properties": {
+                  "modules": {
+                    "$ref": "#/$defs/inherit"
+                  },
+                  "prefixes": {
+                    "$ref": "#/$defs/inherit"
+                  },
+                  "roots": {
+                    "$ref": "#/$defs/inherit"
+                  }
+                }
+              },
               "wheel": {
                 "type": "object",
                 "additionalProperties": false,

src/scikit_build_core/settings/skbuild_model.py

@@ -89,6 +89,28 @@ class SearchSettings:
     paths.
     """
 
+    ignore_entry_point: List[str] = dataclasses.field(default_factory=list)
+    """
+    Entry points to ignore. Any entry-point in `cmake.module`, `cmake.prefix`,
+    `cmake.root` with a key value matching a value in this list will be ignored
+    when building the search paths.
+    """
+
+    modules: List[str] = dataclasses.field(default_factory=list)
+    """
+    List of additional CMake module search paths. Populates `CMAKE_MODULE_PATH`.
+    """
+
+    prefixes: List[str] = dataclasses.field(default_factory=list)
+    """
+    List of additional CMake prefix search paths. Populates `CMAKE_PREFIX_PATH`.
+    """
+
+    roots: Dict[str, str] = dataclasses.field(default_factory=dict)
+    """
+    Dict of package names and prefix paths. Populates `<Pkg>_ROOT`.
+    """
+
 
 @dataclasses.dataclass
 class NinjaSettings: