Flit support for variants.json format + Multiple Props per NS/Feat

DEKHTIARJonathan · DEKHTIARJonathan · commit dc3777cfb67b · 2025-06-13T16:24:01.000-04:00
diff --git a/flit/__init__.py b/flit/__init__.py
@@ -12,7 +12,7 @@
 from .config import ConfigError
 from .log import enable_colourful_output
 
-__version__ = '3.12.0'
+__version__ = '3.12.0+wheelnext'
 
 log = logging.getLogger(__name__)
 
diff --git a/flit/install.py b/flit/install.py
@@ -14,6 +14,7 @@
 from subprocess import check_call, check_output
 import sysconfig
 
+from flit_core.variant_constants import VARIANT_DIST_INFO_FILENAME
 from flit_core import common
 from .config import read_flit_config
 from ._get_dirs import get_dirs
@@ -384,6 +385,10 @@ def write_dist_info(self, site_pkgs):
             metadata.write_metadata_file(f)
         self.installed_files.append(dist_info / 'METADATA')
 
+        with open(osp.join(dist_info, VARIANT_DIST_INFO_FILENAME), 'w', encoding='utf-8') as f:
+            metadata.write_variants_json_file(f)
+        self.installed_files.append(dist_info / VARIANT_DIST_INFO_FILENAME)
+
         with (dist_info / 'INSTALLER').open('w', encoding='utf-8') as f:
             f.write('flit')
         self.installed_files.append(dist_info / 'INSTALLER')
diff --git a/flit_core/flit_core/buildapi.py b/flit_core/flit_core/buildapi.py
@@ -11,6 +11,7 @@
 from .config import read_flit_config
 from .wheel import make_wheel_in, _write_wheel_file
 from .sdist import SdistBuilder
+from .variant_constants import VARIANT_DIST_INFO_FILENAME
 
 log = logging.getLogger(__name__)
 
@@ -57,6 +58,9 @@ def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
     with open(osp.join(dist_info, 'METADATA'), 'w', encoding='utf-8') as f:
         metadata.write_metadata_file(f)
 
+    with open(osp.join(dist_info, VARIANT_DIST_INFO_FILENAME), 'w', encoding='utf-8') as f:
+        metadata.write_variants_json_file(f)
+
     if ini_info.entrypoints:
         with open(osp.join(dist_info, 'entry_points.txt'), 'w', encoding='utf-8') as f:
             write_entry_points(ini_info.entrypoints, f)
diff --git a/flit_core/flit_core/common.py b/flit_core/flit_core/common.py
@@ -1,15 +1,32 @@
 import ast
 from contextlib import contextmanager
+from collections import defaultdict
 import hashlib
 import logging
 import os
 import sys
+import json
+from typing import Any
 
 from pathlib import Path
 import re
 
 log = logging.getLogger(__name__)
 
+from .variant_constants import (
+    VALIDATION_PROPERTY_REGEX, 
+    VARIANTS_JSON_SCHEMA_KEY,
+    VARIANTS_JSON_SCHEMA_URL,
+    VARIANTS_JSON_VARIANT_DATA_KEY,
+    VARIANT_INFO_DEFAULT_PRIO_KEY,
+    VARIANT_INFO_FEATURE_KEY,
+    VARIANT_INFO_NAMESPACE_KEY,
+    VARIANT_INFO_PROPERTY_KEY,
+    VARIANT_INFO_PROVIDER_DATA_KEY,
+    VARIANT_INFO_PROVIDER_PLUGIN_API_KEY, 
+    VARIANT_INFO_PROVIDER_ENABLE_IF_KEY,
+    VARIANT_INFO_PROVIDER_REQUIRES_KEY
+)
 from .versionno import normalise_version
 
 class Module:
@@ -351,13 +368,14 @@ class Metadata:
     license_files = ()
     dynamic = ()
 
-    variant_hash = None
-    variant_properties = ()
-    variant_requires = ()
-    variant_plugin_apis = ()
-    variant_default_namespace_priorities = ()
-    variant_default_feature_priorities = ()
-    variant_default_property_priorities = ()
+    variant_hash: str | None = None
+    variant_properties: list[str] = []
+    variant_plugins: dict[str, dict[str, list[str] | str]] = {}
+    variant_default_priorities: dict[str, Any] = {
+        "namespace": [],
+        "feature": {},
+        "property": {}
+    }
 
     metadata_version = "2.4"
 
@@ -452,26 +470,74 @@ def write_metadata_file(self, fp):
         if self.description is not None:
             fp.write('\n' + self.description + '\n')
 
+
+    def write_variants_json_file(self, fp):
+        """Write out Variant Metadata in json format"""
+
         if self.variant_hash is not None:
-            fp.write('Variant-hash: {}\n'.format(self.variant_hash))
-            for vprop in self.variant_properties:
-                fp.write('Variant-property: {}\n'.format(vprop))
-            for vreq in self.variant_requires:
-                fp.write('Variant-requires: {}\n'.format(vreq))
-            for vAPI in self.variant_plugin_apis:
-                fp.write('Variant-plugin-api: {}\n'.format(vAPI))
-            if self.variant_default_namespace_priorities:
-                fp.write('Variant-default-namespace-priorities: {}\n'.format(
-                    ', '.join(self.variant_default_namespace_priorities)
-                ))
-            if self.variant_default_feature_priorities:
-                fp.write('Variant-default-feature-priorities: {}\n'.format(
-                    ', '.join(self.variant_default_feature_priorities)
-                ))
-            if self.variant_default_property_priorities:
-                fp.write('Variant-default-property-priorities: {}\n'.format(
-                    ', '.join(self.variant_default_property_priorities)
-                ))
+            data = {
+                VARIANTS_JSON_SCHEMA_KEY: VARIANTS_JSON_SCHEMA_URL,
+                VARIANT_INFO_DEFAULT_PRIO_KEY: {},
+                VARIANT_INFO_PROVIDER_DATA_KEY: {},
+                VARIANTS_JSON_VARIANT_DATA_KEY: {}
+            }
+            
+            # ==================== VARIANT_INFO_DEFAULT_PRIO_KEY ==================== #
+            
+            if (ns_prio := self.variant_default_priorities["namespace"]):
+                data[VARIANT_INFO_DEFAULT_PRIO_KEY][VARIANT_INFO_NAMESPACE_KEY] = ns_prio
+
+            if (feat_prio := self.variant_default_priorities["feature"]):
+                data[VARIANT_INFO_DEFAULT_PRIO_KEY][VARIANT_INFO_FEATURE_KEY] = feat_prio
+
+            if (prop_prio := self.variant_default_priorities["property"]):
+                data[VARIANT_INFO_DEFAULT_PRIO_KEY][VARIANT_INFO_PROPERTY_KEY] = prop_prio
+
+            if not data[VARIANT_INFO_DEFAULT_PRIO_KEY]:
+                # If no default priorities are set, remove the key
+                del data[VARIANT_INFO_DEFAULT_PRIO_KEY]
+
+            # ==================== VARIANT_INFO_PROVIDER_DATA_KEY ==================== #
+
+            variant_providers = defaultdict(dict)
+            for ns, plugin_conf in self.variant_plugins.items():
+                variant_providers[ns][VARIANT_INFO_PROVIDER_REQUIRES_KEY] = plugin_conf.get("requires", [])
+                
+                if (enable_if := plugin_conf.get("enable_if", None)) is not None:
+                    variant_providers[ns][VARIANT_INFO_PROVIDER_ENABLE_IF_KEY] = enable_if
+
+                if (plugin_api := plugin_conf.get("plugin_api", None)) is not None:
+                    variant_providers[ns][VARIANT_INFO_PROVIDER_PLUGIN_API_KEY] = plugin_api
+
+            data[VARIANT_INFO_PROVIDER_DATA_KEY] = variant_providers
+            
+            # ==================== VARIANTS_JSON_VARIANT_DATA_KEY ==================== #
+
+            variant_data = defaultdict(lambda: defaultdict(set))
+            for vprop_str in self.variant_properties:
+                match = VALIDATION_PROPERTY_REGEX.match(vprop_str)
+                if not match:
+                    raise ValueError(
+                        f"Invalid variant property '{vprop_str}' in variant {self.variant_hash}"
+                    )
+                namespace = match.group('namespace')
+                feature = match.group('feature')
+                value = match.group('value')
+                variant_data[namespace][feature].add(value)
+            data[VARIANTS_JSON_VARIANT_DATA_KEY][self.variant_hash] = variant_data
+
+            def preprocess(data):
+                """Preprocess the data to ensure it is JSON serializable."""
+                if isinstance(data, (defaultdict, dict)):
+                    return {k: preprocess(v) for k, v in data.items()}
+                if isinstance(data, set):
+                    return list(data)
+                return data
+
+            json.dump(
+                preprocess(data), fp, indent=4, sort_keys=True, ensure_ascii=False
+            )
+        
 
     @property
     def supports_py2(self):
@@ -488,7 +554,7 @@ def make_metadata(module, ini_info):
     md_dict.update(ini_info.metadata)
     vconfig = getattr(ini_info, "variant_config", None)
     if vconfig is not None:
-        md_dict.update(vconfig.to_metadata_dict())
+        md_dict.update(vconfig.to_variant_cfg_dict())
     return Metadata(md_dict)
 
 
diff --git a/flit_core/flit_core/config.py b/flit_core/flit_core/config.py
@@ -287,7 +287,8 @@ def add_scripts(self, scripts_dict):
 @dataclass
 class VariantProviderConfig:
     requires: list[str]
-    plugin_api: str
+    plugin_api: str | None = None
+    enable_if: str | None = None
 
     @classmethod
     def from_dict(cls, data: dict):
@@ -302,8 +303,6 @@ def validate(self):
         """Validates the VariantProviderConfig instance."""
         if not self.requires:
             raise ValueError("Requires list cannot be empty")
-        if not self.plugin_api:
-            raise ValueError("Plugin-API cannot be empty")
 
 
 @dataclass
@@ -365,25 +364,24 @@ def validate(self):
         for provider_cfg in self.providers.values():
             provider_cfg.validate()
 
-    def to_metadata_dict(self) -> dict[str, Any]:
+    def to_variant_cfg_dict(self) -> dict[str, Any]:
         """Converts the VariantConfig instance to a metadata dictionary."""
         return {
             "variant_hash": self.vhash,
             "variant_properties": self.properties,
-            "variant_requires": [
-                f"{namespace}: {preq}"
+            "variant_plugins": {
+                namespace: {
+                    "requires": provider_cfg.requires,
+                    "plugin_api": provider_cfg.plugin_api,
+                    "enable_if": provider_cfg.enable_if
+                }
                 for namespace, provider_cfg in self.providers.items()
-                for preq in provider_cfg.requires
-            ],
-            "variant_plugin_apis": [
-                f"{namespace}: {provider_cfg.plugin_api}"
-                for namespace, provider_cfg in self.providers.items()
-            ],
-            "variant_default_namespace_priorities": self.default_priorities[
-                "namespace"
-            ],
-            "variant_default_feature_priorities": self.default_priorities["feature"],
-            "variant_default_property_priorities": self.default_priorities["property"],
+            },
+            "variant_default_priorities": {
+                "namespace": self.default_priorities.get("namespace", []),
+                "feature": self.default_priorities.get("feature", {}),
+                "property": self.default_priorities.get("property", {})
+            }
         }
 
 
diff --git a/flit_core/flit_core/variant_constants.py b/flit_core/flit_core/variant_constants.py
diff --git a/flit_core/flit_core/wheel.py b/flit_core/flit_core/wheel.py
