Rename bzl files to scl

These files don't have anything to do with bazel, they just use starlark as a configuration
language. Bazel recently introduced the scl file extension to use for this format, which doesn't
have any bazel-specific symbols. Use that extension for our pure starlark files as well.

Bug: 309686282
Test: Presubmits
Change-Id: I7b08f342e7fb94405a52af0918ae6a7d542f3282
diff --git a/core/release_config.scl b/core/release_config.scl
new file mode 100644
index 0000000..101f119
--- /dev/null
+++ b/core/release_config.scl
@@ -0,0 +1,224 @@
+# Copyright (C) 2023 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Export build flags (with values) to make.
+"""
+
+load("//build/bazel/utils:schema_validation.scl", "validate")
+
+# Partitions that get build system flag summaries
+_flag_partitions = [
+    "product",
+    "system",
+    "system_ext",
+    "vendor",
+]
+
+ALL = ["all"]
+PRODUCT = ["product"]
+SYSTEM = ["system"]
+SYSTEM_EXT = ["system_ext"]
+VENDOR = ["vendor"]
+
+_valid_types = ["NoneType", "bool", "list", "string", "int"]
+
+_all_flags_schema = {
+    "type": "list",
+    "of": {
+        "type": "dict",
+        "required_keys": {
+            "name": {"type": "string"},
+            "partitions": {
+                "type": "list",
+                "of": {
+                    "type": "string",
+                    "choices": _flag_partitions + ["all"],
+                },
+                "unique": True,
+            },
+            "default": {
+                "or": [
+                    {"type": t}
+                    for t in _valid_types
+                ],
+            },
+            "declared_in": {"type": "string"},
+        },
+        "optional_keys": {
+            "appends": {
+                "type": "bool",
+            },
+        },
+    },
+}
+
+_all_values_schema = {
+    "type": "list",
+    "of": {
+        "type": "dict",
+        "required_keys": {
+            "name": {"type": "string"},
+            "value": {
+                "or": [
+                    {"type": t}
+                    for t in _valid_types
+                ],
+            },
+            "set_in": {"type": "string"},
+        },
+    },
+}
+
+def flag(name, partitions, default, _kwmarker = (), appends = False):
+    """Declare a flag.
+
+    Args:
+      name: name of the flag
+      partitions: the partitions where this should be recorded.
+      default: the default value of the flag.
+      _kwmarker: Used to detect argument misuse.
+      appends: Whether new values should be append (not replace) the old.
+
+    Returns:
+      A dictionary containing the flag declaration.
+    """
+
+    # If specified, appends must be a keyword value.
+    if _kwmarker != ():
+        fail("Too many positional parameters")
+    if not partitions:
+        fail("At least 1 partition is required")
+    if not name.startswith("RELEASE_"):
+        fail("Release flag names must start with RELEASE_")
+    if " " in name or "\t" in name or "\n" in name:
+        fail("Flag names must not contain whitespace: \"" + name + "\"")
+    for partition in partitions:
+        if partition == "all":
+            if len(partitions) > 1:
+                fail("\"all\" can't be combined with other partitions: " + str(partitions))
+        elif partition not in _flag_partitions:
+            fail("Invalid partition: " + partition + ", allowed partitions: " +
+                 str(_flag_partitions))
+    if type(default) not in _valid_types:
+        fail("Invalid type of default for flag \"" + name + "\" (" + type(default) + ")")
+    return {
+        "name": name,
+        "partitions": partitions,
+        "default": default,
+        "appends": appends,
+    }
+
+def value(name, value):
+    """Define the flag value for a particular configuration.
+
+    Args:
+      name: The name of the flag.
+      value: The value for the flag.
+
+    Returns:
+      A dictionary containing the name and value to be used.
+    """
+    return {
+        "name": name,
+        "value": value,
+    }
+
+def _format_value(val):
+    """Format the starlark type correctly for make.
+
+    Args:
+      val: The value to format
+
+    Returns:
+      The value, formatted correctly for make.
+    """
+    if type(val) == "NoneType":
+        return ""
+    elif type(val) == "bool":
+        return "true" if val else ""
+    else:
+        return val
+
+def release_config(all_flags, all_values):
+    """Return the make variables that should be set for this release config.
+
+    Args:
+      all_flags: A list of flag objects (from flag() calls).
+      all_values: A list of value objects (from value() calls).
+
+    Returns:
+      A dictionary of {name: value} variables for make.
+    """
+    validate(all_flags, _all_flags_schema)
+    validate(all_values, _all_values_schema)
+
+    # Validate flags
+    flag_names = []
+    flags_dict = {}
+    for flag in all_flags:
+        if flag["name"] in flag_names:
+            fail(flag["declared_in"] + ": Duplicate declaration of flag " + flag["name"])
+        flag_names.append(flag["name"])
+        flags_dict[flag["name"]] = flag
+
+    # Record which flags go on which partition
+    partitions = {}
+    for flag in all_flags:
+        for partition in flag["partitions"]:
+            if partition == "all":
+                if len(flag["partitions"]) > 1:
+                    fail("\"all\" can't be combined with other partitions: " + str(flag["partitions"]))
+                for partition in _flag_partitions:
+                    partitions.setdefault(partition, []).append(flag["name"])
+            else:
+                partitions.setdefault(partition, []).append(flag["name"])
+
+    # Generate final values.
+    # Only declared flags may have a value.
+    values = {}
+    for value in all_values:
+        name = value["name"]
+        if name not in flag_names:
+            fail(value["set_in"] + ": Value set for undeclared build flag: " + name)
+        if flags_dict[name]["appends"]:
+            if name in values:
+                values[name]["value"] += " " + value["value"]
+                values[name]["set_in"] += " " + value["set_in"]
+            else:
+                values[name] = value
+        else:
+            values[name] = value
+
+    # Collect values
+    result = {
+        "_ALL_RELEASE_FLAGS": sorted(flag_names),
+    }
+    for partition, names in partitions.items():
+        result["_ALL_RELEASE_FLAGS.PARTITIONS." + partition] = names
+    for flag in all_flags:
+        if flag["name"] in values:
+            val = values[flag["name"]]["value"]
+            set_in = values[flag["name"]]["set_in"]
+        else:
+            val = flag["default"]
+            set_in = flag["declared_in"]
+        val = _format_value(val)
+        result[flag["name"]] = val
+        result["_ALL_RELEASE_FLAGS." + flag["name"] + ".PARTITIONS"] = flag["partitions"]
+        result["_ALL_RELEASE_FLAGS." + flag["name"] + ".DEFAULT"] = _format_value(flag["default"])
+        result["_ALL_RELEASE_FLAGS." + flag["name"] + ".VALUE"] = val
+        result["_ALL_RELEASE_FLAGS." + flag["name"] + ".DECLARED_IN"] = flag["declared_in"]
+        result["_ALL_RELEASE_FLAGS." + flag["name"] + ".SET_IN"] = set_in
+
+    return result