Access sysconfig paths through pyodide config CLI

CHANGELOG.md

@@ -7,6 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## Changed
+
+- The `pyodide config list` command now displays additional config variables
+  derived from the Python `sysconfig` module. These variables may also be accessed
+  through `pyodide config get <variable name>` for use in out-of-tree builds.
+  [#14](https://github.com/pyodide/pyodide-build/pull/14)
+
 ## [0.27.3] - 2024/07/17
 
 - It is now possible to override `_f2c_fixes.py` file, with `_f2c_fixes_wrapper` variable.

pyodide_build/cli/config.py

@@ -1,3 +1,5 @@
+import sysconfig
+
 import typer
 
 from ..build_env import get_build_environment_vars, get_pyodide_root, init_environment
@@ -19,6 +21,13 @@
     "meson_cross_file": "MESON_CROSS_FILE",
 }
 
+# Load the values of sysconfig.get_paths() with a
+# "pyodide_sysconfig_" prefix to differentiate them
+# from other configuration variables
+PYODIDE_CONFIGS.update(
+    {f"pyodide_sysconfig_{k}": v for k, v in sysconfig.get_paths().items()}
+)
+
 
 @app.callback(no_args_is_help=True)
 def callback() -> None:
@@ -52,7 +61,7 @@ def get_config(
     ),
 ) -> None:
     """
-    Get a value of a single config variable used in pyodide
+    Get a value of a single config variable used in Pyodide
     """
     configs = _get_configs()
 

pyodide_build/config.py

@@ -1,5 +1,6 @@
 import os
 import subprocess
+import sysconfig
 from collections.abc import Mapping
 from pathlib import Path
 from types import MappingProxyType
@@ -29,8 +30,15 @@ def __init__(self, pyodide_root: Path):
             **self._load_makefile_envs(),
             **self._load_config_file(Path.cwd(), os.environ),
             **self._load_config_from_env(os.environ),
+            **self._load_sysconfig_paths(),
         }
 
+    def _load_sysconfig_paths(self) -> Mapping[str, str]:
+        # Load the values of sysconfig.get_paths() with a
+        # "pyodide_sysconfig_" prefix to differentiate them
+        # from other configuration variables
+        return {f"pyodide_sysconfig_{k}": v for k, v in sysconfig.get_paths().items()}
+
     def _load_default_config(self) -> Mapping[str, str]:
         return {
             k: _environment_substitute_str(
@@ -173,6 +181,10 @@ def to_env(self) -> dict[str, str]:
     "_f2c_fixes_wrapper": "_F2C_FIXES_WRAPPER",
 }
 
+BUILD_KEY_TO_VAR.update(
+    {f"pyodide_sysconfig_{k}": v for k, v in sysconfig.get_paths().items()}
+)
+
 BUILD_VAR_TO_KEY = {v: k for k, v in BUILD_KEY_TO_VAR.items()}
 
 # Configuration keys that can be overridden by the user.
@@ -205,6 +217,10 @@ def to_env(self) -> dict[str, str]:
     "_f2c_fixes_wrapper": "",
 }
 
+DEFAULT_CONFIG.update(
+    {f"pyodide_sysconfig_{k}": v for k, v in sysconfig.get_paths().items()}
+)
+
 # Default configs that are computed from other values (often from Makefile.envs)
 # TODO: Remove dependency on Makefile.envs
 DEFAULT_CONFIG_COMPUTED: dict[str, str] = {