Add a method to check assigned minimum OS versions to make sure that they fall within Apple-supported requirements.

Starting with watchOS top level rules rather than SDK rules or test rules, as that has fewer dependencies at the moment. Further take this opportunity to move iOS examples up to the recommended minimum OS version of 15.0.

NOTE: updates test data and tests to match new Xcode 16 required min OS versions

Cherry-pick: 2e938c0

Author: nglevin

apple/BUILD

@@ -73,12 +73,12 @@ bzl_library(
     name = "apple_binary",
     srcs = ["apple_binary.bzl"],
     deps = [
+        "//apple/internal:apple_toolchains",
         "//apple/internal:linking_support",
         "//apple/internal:providers",
         "//apple/internal:rule_attrs",
         "//apple/internal:rule_factory",
         "//apple/internal:transition_support",
-        "//apple/internal/toolchains:apple_toolchains",
         "@build_bazel_apple_support//lib:apple_support",
         "@rules_cc//cc/common",
     ],
@@ -282,6 +282,7 @@ bzl_library(
     name = "watchos",
     srcs = ["watchos.bzl"],
     deps = [
+        "//apple/internal:required_minimum_os",
         "//apple/internal:watchos_rules",
         "//apple/internal/testing:apple_test_assembler",
         "//apple/internal/testing:build_test_rules",

apple/internal/BUILD

@@ -668,6 +668,14 @@ bzl_library(
     ],
 )
 
+bzl_library(
+    name = "required_minimum_os",
+    srcs = ["required_minimum_os.bzl"],
+    visibility = [
+        "//apple:__subpackages__",
+    ],
+)
+
 bzl_library(
     name = "transition_support",
     srcs = ["transition_support.bzl"],
@@ -740,6 +748,7 @@ bzl_library(
         ":platform_support",
         ":processor",
         ":providers",
+        ":required_minimum_os",
         ":resources",
         ":rule_attrs",
         ":rule_factory",
@@ -826,7 +835,6 @@ bzl_library(
         "//apple/internal/aspects:resource_aspect_hint",
         "//apple/internal/aspects:swift_usage_aspect",
         "//apple/internal/providers:xcframework_deps_info",
-        "//apple/internal/toolchains:apple_toolchains",
         "//apple/internal/utils:files",
         "@bazel_skylib//lib:partial",
         "@bazel_skylib//lib:paths",

apple/internal/required_minimum_os.bzl

@@ -0,0 +1,48 @@
+# Copyright 2025 The Bazel Authors. All rights reserved.
+#
+# 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.
+
+"""Required minimum OS versions for Apple platforms."""
+
+visibility([
+    "//apple/...",
+    "//test/...",
+])
+
+# Based on https://developer.apple.com/support/xcode/ for Xcode 16 as of 2025-08-01.
+_REQUIRED_MINIMUM_OS_VERSION = {
+    "ios": "15.0",
+    "macos": "10.13",  # TODO: b/433768882 - Move up to 11.0 for Xcode 26.
+    "tvos": "12.0",  # TODO: b/433768882 - Move up to 15.0 for Xcode 16.0.
+    "visionos": "1.0",
+    "watchos": "8.0",
+}
+
+def _validate(*, minimum_os_version, platform_type, rule_label):
+    """Verifies that the given minimum OS version is supported for the given platform type."""
+    if (apple_common.dotted_version(minimum_os_version) <
+        apple_common.dotted_version(_REQUIRED_MINIMUM_OS_VERSION[platform_type])):
+        fail("""
+Error: The declared minimum OS version for {rule_label} is "{minimum_os_version}", which is lower \
+than the required minimum OS version of "{required_minimum_os_version}".
+
+Please update the minimum_os_version attribute to "{required_minimum_os_version}" or higher.
+        """.format(
+            rule_label = str(rule_label),
+            minimum_os_version = minimum_os_version,
+            required_minimum_os_version = _REQUIRED_MINIMUM_OS_VERSION[platform_type],
+        ))
+
+required_minimum_os = struct(
+    validate = _validate,
+)

apple/internal/watchos_rules.bzl

@@ -97,6 +97,10 @@ load(
     "new_watchosapplicationbundleinfo",
     "new_watchosextensionbundleinfo",
 )
+load(
+    "//apple/internal:required_minimum_os.bzl",
+    "required_minimum_os",
+)
 load(
     "//apple/internal:resources.bzl",
     "resources",
@@ -149,6 +153,12 @@ load(
 
 def _watchos_framework_impl(ctx):
     """Experimental implementation of watchos_framework."""
+    required_minimum_os.validate(
+        minimum_os_version = ctx.attr.minimum_os_version,
+        platform_type = ctx.attr.platform_type,
+        rule_label = ctx.label,
+    )
+
     rule_descriptor = rule_support.rule_descriptor(
         platform_type = ctx.attr.platform_type,
         product_type = apple_product_type.framework,
@@ -404,6 +414,12 @@ def _watchos_framework_impl(ctx):
 
 def _watchos_dynamic_framework_impl(ctx):
     """Experimental implementation of watchos_dynamic_framework."""
+    required_minimum_os.validate(
+        minimum_os_version = ctx.attr.minimum_os_version,
+        platform_type = ctx.attr.platform_type,
+        rule_label = ctx.label,
+    )
+
     rule_descriptor = rule_support.rule_descriptor(
         platform_type = ctx.attr.platform_type,
         product_type = apple_product_type.framework,
@@ -707,6 +723,11 @@ def _watchos_dynamic_framework_impl(ctx):
 
 def _watchos_application_impl(ctx):
     """Implementation of watchos_application."""
+    required_minimum_os.validate(
+        minimum_os_version = ctx.attr.minimum_os_version,
+        platform_type = ctx.attr.platform_type,
+        rule_label = ctx.label,
+    )
 
     if ctx.attr.deps:
         return _watchos_single_target_application_impl(ctx)
@@ -715,7 +736,6 @@ def _watchos_application_impl(ctx):
 
 def _watchos_extension_based_application_impl(ctx):
     """Implementation of watchos_application for watchOS 2 extension-based application bundles."""
-
     minimum_os = apple_common.dotted_version(ctx.attr.minimum_os_version)
     if minimum_os >= apple_common.dotted_version("9.0"):
         fail("""
@@ -1008,6 +1028,11 @@ reproducible error case.".format(
 
 def _watchos_extension_impl(ctx):
     """Implementation of watchos_extension."""
+    required_minimum_os.validate(
+        minimum_os_version = ctx.attr.minimum_os_version,
+        platform_type = ctx.attr.platform_type,
+        rule_label = ctx.label,
+    )
 
     # TODO(b/155313625): Set the product type as apple_product_type.extension if the attrs set on
     # the rule match a criteria appropriate for watchOS extensions (i.e. SiriKit, Notification
@@ -1326,6 +1351,12 @@ def _watchos_extension_impl(ctx):
 
 def _watchos_static_framework_impl(ctx):
     """Implementation of watchos_static_framework."""
+    required_minimum_os.validate(
+        minimum_os_version = ctx.attr.minimum_os_version,
+        platform_type = ctx.attr.platform_type,
+        rule_label = ctx.label,
+    )
+
     rule_descriptor = rule_support.rule_descriptor(
         platform_type = ctx.attr.platform_type,
         product_type = apple_product_type.static_framework,
@@ -1483,7 +1514,6 @@ def _watchos_static_framework_impl(ctx):
 
 def _watchos_single_target_application_impl(ctx):
     """Implementation of watchos_application for single target watch applications."""
-
     minimum_os = apple_common.dotted_version(ctx.attr.minimum_os_version)
     if minimum_os < apple_common.dotted_version("7.0"):
         fail("Single-target watchOS applications require a minimum_os_version of 7.0 or greater.")

apple/ios.bzl

@@ -125,7 +125,7 @@ Typical usage:
 ```starlark
 ios_build_test(
     name = "my_build_test",
-    minimum_os_version = "12.0",
+    minimum_os_version = "15.0",
     targets = [
         "//some/package:my_library",
     ],

apple/tvos.bzl

@@ -77,7 +77,7 @@ Typical usage:
 ```starlark
 tvos_build_test(
     name = "my_build_test",
-    minimum_os_version = "12.0",
+    minimum_os_version = "15.0",
     targets = [
         "//some/package:my_library",
     ],

apple/watchos.bzl

@@ -77,7 +77,7 @@ Typical usage:
 ```starlark
 watchos_build_test(
     name = "my_build_test",
-    minimum_os_version = "6.0",
+    minimum_os_version = "8.0",
     targets = [
         "//some/package:my_library",
     ],

doc/rules-ios.md

@@ -139,7 +139,7 @@ Typical usage:
 ```starlark
 ios_build_test(
     name = "my_build_test",
-    minimum_os_version = "12.0",
+    minimum_os_version = "15.0",
     targets = [
         "//some/package:my_library",
     ],

doc/rules-tvos.md

@@ -79,7 +79,7 @@ Typical usage:
 ```starlark
 tvos_build_test(
     name = "my_build_test",
-    minimum_os_version = "12.0",
+    minimum_os_version = "15.0",
     targets = [
         "//some/package:my_library",
     ],

doc/rules-watchos.md

@@ -77,7 +77,7 @@ Typical usage:
 ```starlark
 watchos_build_test(
     name = "my_build_test",
-    minimum_os_version = "6.0",
+    minimum_os_version = "8.0",
     targets = [
         "//some/package:my_library",
     ],