Route Xcode version information through an implicit dependency instead of the configuration.

This is part of the crusade to kill package loading in configuration creation.

AppleConfiguration still retains the version information for the following reasons:
- Some Skylark rules access it that way. The plan is to create an xcode_config_alias() rule that can be an implicit dependency of Skylark rules and to export the version information to Skylark from XcodeVersionsProvider.
- The minimum OS version is part of the name of the output directory. The plan for that is simply to remove it. Hopefully we can get away with it.
- They allow us to add assertions to make sure the new mechanism works like the old one.

RELNOTES: None.
PiperOrigin-RevId: 163038724

22 files changed, 352 insertions, 89 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java
index 97027f3d99..3ab182ad59 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/AppleConfiguration.java
@@ -20,6 +20,7 @@ import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationEnvironment;
@@ -93,14 +94,15 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
   private final Label xcodeConfigLabel;
   private final DottedVersion xcodeVersionCommandLineFlag;
   private final boolean enableAppleCrosstool;
+  private final AppleCommandLineOptions options;
   @Nullable private final String xcodeToolchain;
   @Nullable private final Label defaultProvisioningProfileLabel;
   private final boolean mandatoryMinimumVersion;
 
   AppleConfiguration(
-      AppleCommandLineOptions appleOptions,
+      AppleCommandLineOptions options,
       String cpu,
-      @Nullable DottedVersion xcodeVersion,
+      XcodeVersionProperties xcodeVersionProperties,
       DottedVersion iosSdkVersion,
       DottedVersion iosMinimumOs,
       DottedVersion watchosSdkVersion,
@@ -109,6 +111,7 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
       DottedVersion tvosMinimumOs,
       DottedVersion macosSdkVersion,
       DottedVersion macosMinimumOs) {
+    this.options = options;
     this.iosSdkVersion = Preconditions.checkNotNull(iosSdkVersion, "iosSdkVersion");
     this.iosMinimumOs = Preconditions.checkNotNull(iosMinimumOs, "iosMinimumOs");
     this.watchosSdkVersion =
@@ -123,31 +126,31 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
         Preconditions.checkNotNull(macosSdkVersion, "macOsSdkVersion");
     this.macosMinimumOs = Preconditions.checkNotNull(macosMinimumOs, "macOsMinimumOs");
 
-    this.xcodeVersion = xcodeVersion;
+    this.xcodeVersion = xcodeVersionProperties.getXcodeVersion().orNull();
     this.iosCpu = iosCpuFromCpu(cpu);
-    this.appleSplitCpu = Preconditions.checkNotNull(appleOptions.appleSplitCpu, "appleSplitCpu");
+    this.appleSplitCpu = Preconditions.checkNotNull(options.appleSplitCpu, "appleSplitCpu");
     this.applePlatformType =
-        Preconditions.checkNotNull(appleOptions.applePlatformType, "applePlatformType");
-    this.configurationDistinguisher = appleOptions.configurationDistinguisher;
+        Preconditions.checkNotNull(options.applePlatformType, "applePlatformType");
+    this.configurationDistinguisher = options.configurationDistinguisher;
     this.iosMultiCpus = ImmutableList.copyOf(
-        Preconditions.checkNotNull(appleOptions.iosMultiCpus, "iosMultiCpus"));
-    this.watchosCpus = (appleOptions.watchosCpus == null || appleOptions.watchosCpus.isEmpty())
+        Preconditions.checkNotNull(options.iosMultiCpus, "iosMultiCpus"));
+    this.watchosCpus = (options.watchosCpus == null || options.watchosCpus.isEmpty())
         ? ImmutableList.of(AppleCommandLineOptions.DEFAULT_WATCHOS_CPU)
-        : ImmutableList.copyOf(appleOptions.watchosCpus);
-    this.tvosCpus = (appleOptions.tvosCpus == null || appleOptions.tvosCpus.isEmpty())
+        : ImmutableList.copyOf(options.watchosCpus);
+    this.tvosCpus = (options.tvosCpus == null || options.tvosCpus.isEmpty())
         ? ImmutableList.of(AppleCommandLineOptions.DEFAULT_TVOS_CPU)
-        : ImmutableList.copyOf(appleOptions.tvosCpus);
-    this.macosCpus = (appleOptions.macosCpus == null || appleOptions.macosCpus.isEmpty())
+        : ImmutableList.copyOf(options.tvosCpus);
+    this.macosCpus = (options.macosCpus == null || options.macosCpus.isEmpty())
         ? ImmutableList.of(AppleCommandLineOptions.DEFAULT_MACOS_CPU)
-        : ImmutableList.copyOf(appleOptions.macosCpus);
-    this.bitcodeMode = appleOptions.appleBitcodeMode;
+        : ImmutableList.copyOf(options.macosCpus);
+    this.bitcodeMode = options.appleBitcodeMode;
     this.xcodeConfigLabel =
-        Preconditions.checkNotNull(appleOptions.xcodeVersionConfig, "xcodeConfigLabel");
-    this.xcodeVersionCommandLineFlag = appleOptions.xcodeVersion;
-    this.enableAppleCrosstool = appleOptions.enableAppleCrosstoolTransition;
-    this.defaultProvisioningProfileLabel = appleOptions.defaultProvisioningProfile;
-    this.xcodeToolchain = appleOptions.xcodeToolchain;
-    this.mandatoryMinimumVersion = appleOptions.mandatoryMinimumVersion;
+        Preconditions.checkNotNull(options.xcodeVersionConfig, "xcodeConfigLabel");
+    this.xcodeVersionCommandLineFlag = options.xcodeVersion;
+    this.enableAppleCrosstool = options.enableAppleCrosstoolTransition;
+    this.defaultProvisioningProfileLabel = options.defaultProvisioningProfile;
+    this.xcodeToolchain = options.xcodeToolchain;
+    this.mandatoryMinimumVersion = options.mandatoryMinimumVersion;
   }
 
   /** Determines cpu value from apple-specific toolchain identifier. */
@@ -159,24 +162,37 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
     }
   }
 
+  public AppleCommandLineOptions getOptions() {
+    return options;
+  }
+
   /**
    * Returns the minimum iOS version supported by binaries and libraries. Any dependencies on newer
    * iOS version features or libraries will become weak dependencies which are only loaded if the
    * runtime OS supports them.
+   *
+   * @deprecated use {@link XcodeConfig#getMinimumOsForPlatformType(RuleContext, PlatformType)}.
    */
   @SkylarkCallable(name = "ios_minimum_os", structField = true,
       doc = "<b>Deprecated. Use <a href='#minimum_os_for_platform_type'>"
           + "minimum_os_for_platform_type(apple_common.platform_type.ios)</a> instead.</b> "
           + "The minimum compatible iOS version for target simulators and devices.")
+  @Deprecated
+  // Bug tracking the removal of this method: https://github.com/bazelbuild/bazel/issues/3424
   public DottedVersion getMinimumOs() {
     // TODO(bazel-team): Deprecate in favor of getMinimumOsForPlatformType(IOS).
     return iosMinimumOs;
   }
 
+  /***
+   * @deprecated use {@link XcodeConfig#getMinimumOsForPlatformType(RuleContext, PlatformType)}.
+   */
   @SkylarkCallable(
       name = "minimum_os_for_platform_type",
       doc = "The minimum compatible OS version for target simulator and devices for a particular "
           + "platform type.")
+  @Deprecated
+  // Bug tracking the removal of this method: https://github.com/bazelbuild/bazel/issues/3424
   public DottedVersion getMinimumOsForPlatformType(PlatformType platformType) {
     // TODO(b/37240784): Look into using only a single minimum OS flag tied to the current
     // apple_platform_type.
@@ -199,8 +215,9 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
    * Returns the SDK version for ios SDKs (whether they be for simulator or device). This is
    * directly derived from --ios_sdk_version.
    *
-   * @deprecated - use {@link #getSdkVersionForPlatform()}
+   * @deprecated use {@link XcodeConfig#getSdkVersionForPlatform(RuleContext, ApplePlatform)}
    */
+  // Bug tracking the removal of this method: https://github.com/bazelbuild/bazel/issues/3424
   @Deprecated public DottedVersion getIosSdkVersion() {
     return getSdkVersionForPlatform(ApplePlatform.IOS_DEVICE);
   }
@@ -208,11 +225,15 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
   /**
    * Returns the SDK version for a platform (whether they be for simulator or device). This is
    * directly derived from command line args.
+   *
+   * @deprecated use {@link XcodeConfig#getSdkVersionForPlatform(RuleContext, ApplePlatform)}
    */
   @SkylarkCallable(
       name = "sdk_version_for_platform",
       doc = "The version of the platform SDK that will be used to build targets for the given "
           + "platform.")
+  @Deprecated
+  // Bug tracking the removal of this method: https://github.com/bazelbuild/bazel/issues/3424
   public DottedVersion getSdkVersionForPlatform(ApplePlatform platform) {
     switch (platform) {
       case IOS_DEVICE:
@@ -235,6 +256,8 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
    * Returns the value of the xcode version, if available. This is determined based on a combination
    * of the {@code --xcode_version} build flag and the {@code xcode_config} target defined in the
    * {@code --xcode_version_config} flag. Returns null if no xcode is available.
+   *
+   * @deprecated use {@link XcodeConfig#getXcodeVersion(RuleContext)}.
    */
   @SkylarkCallable(
       name = "xcode_version",
@@ -242,6 +265,8 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
           + "This will return <code>None</code> if no Xcode versions are available.",
       allowReturnNones = true)
   @Nullable
+  @Deprecated
+  // Bug tracking the removal of this method: https://github.com/bazelbuild/bazel/issues/3424
   public DottedVersion getXcodeVersion() {
     return xcodeVersion;
   }
@@ -677,7 +702,7 @@ public class AppleConfiguration extends BuildConfiguration.Fragment {
           new AppleConfiguration(
               appleOptions,
               cpu,
-              xcodeVersionProperties.getXcodeVersion().orNull(),
+              xcodeVersionProperties,
               iosSdkVersion,
               iosMinimumOsVersion,
               watchosSdkVersion,
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/AppleToolchain.java b/src/main/java/com/google/devtools/build/lib/rules/apple/AppleToolchain.java
index a9c4b49233..35bd1d7991 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/AppleToolchain.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/AppleToolchain.java
@@ -14,12 +14,12 @@
 
 package com.google.devtools.build.lib.rules.apple;
 
-import static com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition.HOST;
 import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
@@ -119,12 +119,12 @@ public class AppleToolchain {
 
   /** Returns the SDK frameworks directory inside of Xcode for a given configuration. */
   public static String sdkFrameworkDir(
-      ApplePlatform targetPlatform, AppleConfiguration configuration) {
+      ApplePlatform targetPlatform, RuleContext ruleContext) {
     String relativePath;
     switch (targetPlatform) {
       case IOS_DEVICE:
       case IOS_SIMULATOR:
-        if (configuration.getSdkVersionForPlatform(targetPlatform)
+        if (XcodeConfig.getSdkVersionForPlatform(ruleContext, targetPlatform)
             .compareTo(DottedVersion.fromString("9.0")) >= 0) {
           relativePath = SYSTEM_FRAMEWORK_PATH;
         } else {
@@ -175,11 +175,10 @@ public class AppleToolchain {
     @Override
     public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
       return builder
-          .add(attr(":xcode_config", LABEL)
+          .add(attr(XcodeConfigRule.XCODE_CONFIG_ATTR_NAME, LABEL)
               .allowedRuleClasses("xcode_config")
               .checkConstraints()
               .direct_compile_time_input()
-              .cfg(HOST)
               .value(new XcodeConfigLabel(toolsRepository)))
           .build();
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfig.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfig.java
index a486e99c56..e9cfddbf1c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfig.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfig.java
@@ -15,10 +15,12 @@
 package com.google.devtools.build.lib.rules.apple;
 
 import com.google.common.base.Joiner;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
 import com.google.devtools.build.lib.analysis.RedirectChaser;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.RunfilesProvider;
@@ -36,6 +38,7 @@ import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.syntax.Type;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import javax.annotation.Nullable;
 
 /**
@@ -101,8 +104,56 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
   @Override
   public ConfiguredTarget create(RuleContext ruleContext)
       throws InterruptedException, RuleErrorException {
+    AppleCommandLineOptions appleOptions =
+        ruleContext.getFragment(AppleConfiguration.class).getOptions();
+    XcodeVersionRuleData defaultVersion = ruleContext.getPrerequisite(
+        XcodeConfigRule.DEFAULT_ATTR_NAME, RuleConfiguredTarget.Mode.TARGET,
+        XcodeVersionRuleData.class);
+    Iterable<XcodeVersionRuleData> availableVersions = ruleContext.getPrerequisites(
+        XcodeConfigRule.VERSIONS_ATTR_NAME, RuleConfiguredTarget.Mode.TARGET,
+        XcodeVersionRuleData.class);
+    boolean requireDefinedVersions = ruleContext.attributes().get(
+        XcodeConfigRule.REQUIRE_DEFINED_VERSIONS_ATTR_NAME, Type.BOOLEAN);
+    XcodeVersionProperties xcodeVersionProperties;
+    try {
+      xcodeVersionProperties = resolveXcodeVersion(
+          requireDefinedVersions,
+          appleOptions.xcodeVersion,
+          availableVersions,
+          defaultVersion);
+    } catch (XcodeConfigException e) {
+      ruleContext.ruleError(e.getMessage());
+      return null;
+    }
+
+    DottedVersion iosSdkVersion = (appleOptions.iosSdkVersion != null)
+        ? appleOptions.iosSdkVersion : xcodeVersionProperties.getDefaultIosSdkVersion();
+    DottedVersion iosMinimumOsVersion = (appleOptions.iosMinimumOs != null)
+        ? appleOptions.iosMinimumOs : iosSdkVersion;
+    DottedVersion watchosSdkVersion = (appleOptions.watchOsSdkVersion != null)
+        ? appleOptions.watchOsSdkVersion : xcodeVersionProperties.getDefaultWatchosSdkVersion();
+    DottedVersion watchosMinimumOsVersion = (appleOptions.watchosMinimumOs != null)
+        ? appleOptions.watchosMinimumOs : watchosSdkVersion;
+    DottedVersion tvosSdkVersion = (appleOptions.tvOsSdkVersion != null)
+        ? appleOptions.tvOsSdkVersion : xcodeVersionProperties.getDefaultTvosSdkVersion();
+    DottedVersion tvosMinimumOsVersion = (appleOptions.tvosMinimumOs != null)
+        ? appleOptions.tvosMinimumOs : tvosSdkVersion;
+    DottedVersion macosSdkVersion = (appleOptions.macOsSdkVersion != null)
+        ? appleOptions.macOsSdkVersion : xcodeVersionProperties.getDefaultMacosSdkVersion();
+    DottedVersion macosMinimumOsVersion = (appleOptions.macosMinimumOs != null)
+        ? appleOptions.macosMinimumOs : macosSdkVersion;
+
+    XcodeConfigProvider xcodeVersions = new XcodeConfigProvider(
+        iosSdkVersion, iosMinimumOsVersion,
+        watchosSdkVersion, watchosMinimumOsVersion,
+        tvosSdkVersion, tvosMinimumOsVersion,
+        macosSdkVersion, macosMinimumOsVersion,
+        xcodeVersionProperties.getXcodeVersion().orNull());
+
     return new RuleConfiguredTargetBuilder(ruleContext)
         .addProvider(RunfilesProvider.class, RunfilesProvider.EMPTY)
+        .addProvider(xcodeVersions)
+        .addNativeDeclaredProvider(xcodeVersionProperties)
         .build();
   }
   
@@ -121,7 +172,7 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
   static XcodeVersionProperties resolveXcodeVersion(
       boolean requireDefinedVersions,
       DottedVersion xcodeVersionOverrideFlag,
-      ImmutableList<XcodeVersionRuleData> xcodeVersions,
+      Iterable<XcodeVersionRuleData> xcodeVersions,
       @Nullable XcodeVersionRuleData defaultVersion)
       throws XcodeConfigException {
     XcodeVersionRuleData xcodeVersion = resolveExplicitlyDefinedVersion(
@@ -147,7 +198,7 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
   @Nullable
   private static XcodeVersionRuleData resolveExplicitlyDefinedVersion(
       boolean requireDefinedVersions,
-      ImmutableList<XcodeVersionRuleData> xcodeVersionRules,
+      Iterable<XcodeVersionRuleData> xcodeVersionRules,
       @Nullable XcodeVersionRuleData defaultVersion,
       DottedVersion versionOverrideFlag)
       throws XcodeConfigException {
@@ -202,7 +253,7 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
    *     were registered to the same alias)
    */
   private static Map<String, XcodeVersionRuleData> aliasesToVersionMap(
-      ImmutableList<XcodeVersionRuleData> xcodeVersionRules)
+      Iterable<XcodeVersionRuleData> xcodeVersionRules)
       throws XcodeConfigException {
     Map<String, XcodeVersionRuleData> aliasesToXcodeRules = Maps.newLinkedHashMap();
     for (XcodeVersionRuleData xcodeVersionRule : xcodeVersionRules) {
@@ -229,7 +280,7 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
    * of duplicate aliases in an {@code xcode_config} target definition. 
    */
   private static void configErrorDuplicateAlias(String alias,
-      List<XcodeVersionRuleData> xcodeVersionRules) throws XcodeConfigException {
+      Iterable<XcodeVersionRuleData> xcodeVersionRules) throws XcodeConfigException {
 
     ImmutableList.Builder<Label> labelsContainingAlias = ImmutableList.builder();
     for (XcodeVersionRuleData xcodeVersionRule : xcodeVersionRules) {
@@ -275,4 +326,59 @@ public class XcodeConfig implements RuleConfiguredTargetFactory {
       throw new InvalidConfigurationException(exception);
     }
   }
+
+  /**
+   * Returns the minimum compatible OS version for target simulator and devices for a particular
+   * platform type.
+   */
+  public static DottedVersion getMinimumOsForPlatformType(
+      RuleContext ruleContext, ApplePlatform.PlatformType platformType) {
+    AppleConfiguration config = ruleContext.getFragment(AppleConfiguration.class);
+    XcodeConfigProvider versions = ruleContext.getPrerequisite(
+        XcodeConfigRule.XCODE_CONFIG_ATTR_NAME,
+        RuleConfiguredTarget.Mode.TARGET,
+        XcodeConfigProvider.class);
+    DottedVersion fromProvider = versions.getMinimumOsForPlatformType(platformType);
+    DottedVersion fromConfig = config.getMinimumOsForPlatformType(platformType);
+    // This sanity check is there to keep this provider in sync with AppleConfiguration until the
+    // latter can be removed. Tracking bug: https://github.com/bazelbuild/bazel/issues/3424
+    Preconditions.checkState(fromProvider.equals(fromConfig));
+    return fromProvider;
+  }
+
+  /**
+   * Returns the SDK version for a platform (whether they be for simulator or device). This is
+   * directly derived from command line args.
+   */
+  public static DottedVersion getSdkVersionForPlatform(
+      RuleContext ruleContext, ApplePlatform platform) {
+    XcodeConfigProvider versions = ruleContext.getPrerequisite(
+        XcodeConfigRule.XCODE_CONFIG_ATTR_NAME,
+        RuleConfiguredTarget.Mode.TARGET,
+        XcodeConfigProvider.class);
+    DottedVersion fromProvider = versions.getSdkVersionForPlatform(platform);
+    DottedVersion fromConfig = ruleContext.getFragment(AppleConfiguration.class)
+        .getSdkVersionForPlatform(platform);
+    // This sanity check is there to keep this provider in sync with AppleConfiguration until the
+    // latter can be removed. Tracking bug: https://github.com/bazelbuild/bazel/issues/3424
+    Preconditions.checkState(fromProvider.equals(fromConfig));
+    return fromProvider;
+  }
+
+  /**
+   * Returns the value of the xcode version, if available. This is determined based on a combination
+   * of the {@code --xcode_version} build flag and the {@code xcode_config} target defined in the
+   * {@code --xcode_version_config} flag. Returns null if no xcode is available.
+   */
+  public static DottedVersion getXcodeVersion(RuleContext ruleContext) {
+    XcodeConfigProvider versions = ruleContext.getPrerequisite(
+        XcodeConfigRule.XCODE_CONFIG_ATTR_NAME,
+        RuleConfiguredTarget.Mode.TARGET, XcodeConfigProvider.class);
+    DottedVersion fromProvider = versions.getXcodeVersion();
+    DottedVersion fromConfig = ruleContext.getFragment(AppleConfiguration.class).getXcodeVersion();
+    // This sanity check is there to keep this provider in sync with AppleConfiguration until the
+    // latter can be removed. Tracking bug: https://github.com/bazelbuild/bazel/issues/3424
+    Preconditions.checkState(Objects.equals(fromProvider, fromConfig));
+    return fromProvider;
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigProvider.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigProvider.java
new file mode 100644
index 0000000000..ce138da4dc
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigProvider.java
@@ -0,0 +1,91 @@
+// Copyright 2017 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.
+package com.google.devtools.build.lib.rules.apple;
+
+import com.google.common.base.Preconditions;
+import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import javax.annotation.Nullable;
+
+/**
+ * The set of Apple versions computed from command line options and the {@code xcode_config} rule.
+ */
+@Immutable
+public class XcodeConfigProvider implements TransitiveInfoProvider {
+  private final DottedVersion iosSdkVersion;
+  private final DottedVersion iosMinimumOsVersion;
+  private final DottedVersion watchosSdkVersion;
+  private final DottedVersion watchosMinimumOsVersion;
+  private final DottedVersion tvosSdkVersion;
+  private final DottedVersion tvosMinimumOsVersion;
+  private final DottedVersion macosSdkVersion;
+  private final DottedVersion macosMinimumOsVersion;
+  @Nullable private final DottedVersion xcodeVersion;
+
+  public XcodeConfigProvider(
+      DottedVersion iosSdkVersion, DottedVersion iosMinimumOsVersion,
+      DottedVersion watchosSdkVersion, DottedVersion watchosMinimumOsVersion,
+      DottedVersion tvosSdkVersion, DottedVersion tvosMinimumOsVersion,
+      DottedVersion macosSdkVersion, DottedVersion macosMinimumOsVersion,
+      DottedVersion xcodeVersion) {
+    this.iosSdkVersion = Preconditions.checkNotNull(iosSdkVersion);
+    this.iosMinimumOsVersion = Preconditions.checkNotNull(iosMinimumOsVersion);
+    this.watchosSdkVersion = Preconditions.checkNotNull(watchosSdkVersion);
+    this.watchosMinimumOsVersion = Preconditions.checkNotNull(watchosMinimumOsVersion);
+    this.tvosSdkVersion = Preconditions.checkNotNull(tvosSdkVersion);
+    this.tvosMinimumOsVersion = Preconditions.checkNotNull(tvosMinimumOsVersion);
+    this.macosSdkVersion = Preconditions.checkNotNull(macosSdkVersion);
+    this.macosMinimumOsVersion = Preconditions.checkNotNull(macosMinimumOsVersion);
+    this.xcodeVersion = xcodeVersion;
+  }
+
+  public DottedVersion getXcodeVersion() {
+    return xcodeVersion;
+  }
+
+  public DottedVersion getMinimumOsForPlatformType(ApplePlatform.PlatformType platformType) {
+    // TODO(b/37240784): Look into using only a single minimum OS flag tied to the current
+    // apple_platform_type.
+    switch (platformType) {
+      case IOS:
+        return iosMinimumOsVersion;
+      case TVOS:
+        return tvosMinimumOsVersion;
+      case WATCHOS:
+        return watchosMinimumOsVersion;
+      case MACOS:
+        return macosMinimumOsVersion;
+      default:
+        throw new IllegalArgumentException("Unhandled platform type: " + platformType);
+    }
+  }
+
+  public DottedVersion getSdkVersionForPlatform(ApplePlatform platform) {
+    switch (platform) {
+      case IOS_DEVICE:
+      case IOS_SIMULATOR:
+        return iosSdkVersion;
+      case TVOS_DEVICE:
+      case TVOS_SIMULATOR:
+        return tvosSdkVersion;
+      case WATCHOS_DEVICE:
+      case WATCHOS_SIMULATOR:
+        return watchosSdkVersion;
+      case MACOS:
+        return macosSdkVersion;
+      default:
+        throw new IllegalArgumentException("Unhandled platform: " + platform);
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigRule.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigRule.java
index de5a2bc618..1b5a4adf40 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigRule.java
@@ -30,6 +30,7 @@ import com.google.devtools.build.lib.packages.RuleClass.Builder;
  */
 public class XcodeConfigRule implements RuleDefinition {
 
+  public static final String XCODE_CONFIG_ATTR_NAME = ":xcode_config";
   static final String DEFAULT_ATTR_NAME = "default";
   static final String VERSIONS_ATTR_NAME = "versions";
   static final String REQUIRE_DEFINED_VERSIONS_ATTR_NAME = "require_defined_version";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersion.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersion.java
index 7d94b725d8..509588f62d 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersion.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersion.java
@@ -33,6 +33,7 @@ public class XcodeVersion implements RuleConfiguredTargetFactory {
 
     return new RuleConfiguredTargetBuilder(ruleContext)
         .addProvider(RunfilesProvider.class, RunfilesProvider.EMPTY)
+        .addProvider(ruleData)
         .addNativeDeclaredProvider(ruleData.getXcodeVersionProperties())
         .build();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionRuleData.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionRuleData.java
index 7a40726cb5..aa9ad6a5f2 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionRuleData.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionRuleData.java
@@ -16,11 +16,12 @@ package com.google.devtools.build.lib.rules.apple;
 
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.syntax.Type;
-
 import java.util.List;
 
 /**
@@ -33,7 +34,8 @@ import java.util.List;
  * "7.0" aliases. This official version of xcode may have a default supported iOS SDK of
  * 9.0.
  */
-public class XcodeVersionRuleData {
+@Immutable
+public class XcodeVersionRuleData implements TransitiveInfoProvider {
   private final Label label;
   private final DottedVersion version;
   private final XcodeVersionProperties xcodeVersionProperties;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchain.java b/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchain.java
index dda418e5c2..d7b297cebf 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchain.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchain.java
@@ -24,6 +24,7 @@ import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.AppleToolchain;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.cpp.CcToolchain;
 import com.google.devtools.build.lib.rules.cpp.CppConfiguration;
 import java.util.LinkedHashMap;
@@ -58,7 +59,7 @@ public class AppleCcToolchain extends CcToolchain {
       throws RuleErrorException {
     AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);
 
-    if (appleConfiguration.getXcodeVersion() == null) {
+    if (XcodeConfig.getXcodeVersion(ruleContext) == null) {
       ruleContext.throwWithRuleError("Xcode version must be specified to use an Apple CROSSTOOL");
     }
 
@@ -69,29 +70,25 @@ public class AppleCcToolchain extends CcToolchain {
     return ImmutableMap.<String, String>builder()
         .put(
             XCODE_VERSION_KEY,
-            appleConfiguration.getXcodeVersion().toStringWithMinimumComponents(2))
+            XcodeConfig.getXcodeVersion(ruleContext).toStringWithMinimumComponents(2))
         .put(
             IOS_SDK_VERSION_KEY,
-            appleConfiguration
-                .getSdkVersionForPlatform(ApplePlatform.IOS_SIMULATOR)
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, ApplePlatform.IOS_SIMULATOR)
                 .toStringWithMinimumComponents(2))
         .put(
             MACOS_SDK_VERSION_KEY,
-            appleConfiguration
-                .getSdkVersionForPlatform(ApplePlatform.MACOS)
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, ApplePlatform.MACOS)
                 .toStringWithMinimumComponents(2))
         .put(
             TVOS_SDK_VERSION_KEY,
-            appleConfiguration
-                .getSdkVersionForPlatform(ApplePlatform.TVOS_SIMULATOR)
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, ApplePlatform.TVOS_SIMULATOR)
                 .toStringWithMinimumComponents(2))
         .put(
             WATCHOS_SDK_VERSION_KEY,
-            appleConfiguration
-                .getSdkVersionForPlatform(ApplePlatform.WATCHOS_SIMULATOR)
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, ApplePlatform.WATCHOS_SIMULATOR)
                 .toStringWithMinimumComponents(2))
         .put(SDK_DIR_KEY, AppleToolchain.sdkDir())
-        .put(SDK_FRAMEWORK_DIR_KEY, AppleToolchain.sdkFrameworkDir(platform, appleConfiguration))
+        .put(SDK_FRAMEWORK_DIR_KEY, AppleToolchain.sdkFrameworkDir(platform, ruleContext))
         .put(
             PLATFORM_DEVELOPER_FRAMEWORK_DIR,
             AppleToolchain.platformDeveloperFrameworkDir(appleConfiguration))
@@ -106,7 +103,7 @@ public class AppleCcToolchain extends CcToolchain {
             appleEnv.getOrDefault(AppleConfiguration.APPLE_SDK_PLATFORM_ENV_NAME, ""))
         .put(
             VERSION_MIN_KEY,
-            appleConfiguration.getMinimumOsForPlatformType(platform.getType()).toString())
+            XcodeConfig.getMinimumOsForPlatformType(ruleContext, platform.getType()).toString())
         .build();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchainRule.java b/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchainRule.java
index 2c4d278479..4be2c9e25a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchainRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchainRule.java
@@ -19,6 +19,7 @@ import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
 import com.google.devtools.build.lib.packages.RuleClass;
 import com.google.devtools.build.lib.packages.RuleClass.Builder;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+import com.google.devtools.build.lib.rules.apple.AppleToolchain;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainRule;
 
 /**
@@ -35,7 +36,8 @@ public class AppleCcToolchainRule implements RuleDefinition {
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("apple_cc_toolchain")
-        .ancestors(BaseRuleClasses.BaseRule.class, CcToolchainRule.class)
+        .ancestors(BaseRuleClasses.BaseRule.class, CcToolchainRule.class,
+            AppleToolchain.RequiresXcodeConfigRule.class)
         .factoryClass(AppleCcToolchain.class)
         .build();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
index 304930f441..79ae78973a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BinaryLinkingTargetFactory.java
@@ -33,6 +33,7 @@ import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
 import com.google.devtools.build.lib.rules.objc.ObjcCommon.ResourceAttributes;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.LinkedBinary;
@@ -156,7 +157,7 @@ abstract class BinaryLinkingTargetFactory implements RuleConfiguredTargetFactory
                 objcProvider,
                 LinkedBinary.LOCAL_AND_DEPENDENCIES,
                 ReleaseBundlingSupport.APP_BUNDLE_DIR_FORMAT,
-                appleConfiguration.getMinimumOsForPlatformType(PlatformType.IOS),
+                XcodeConfig.getMinimumOsForPlatformType(ruleContext, PlatformType.IOS),
                 appleConfiguration.getSingleArchPlatform());
         releaseBundlingSupport
             .registerActions(DsymOutputType.APP)
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
index a89cb98642..0b9f89487b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
@@ -16,8 +16,8 @@ package com.google.devtools.build.lib.rules.objc;
 
 import com.google.common.io.ByteSource;
 import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
-import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
+import com.google.devtools.build.lib.rules.apple.ApplePlatform;
+import com.google.devtools.build.lib.rules.apple.DottedVersion;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.xcode.bundlemerge.proto.BundleMergeProtos;
 import com.google.devtools.build.xcode.bundlemerge.proto.BundleMergeProtos.Control;
@@ -34,13 +34,16 @@ import java.io.InputStream;
 final class BundleMergeControlBytes extends ByteSource {
   private final Bundling rootBundling;
   private final Artifact mergedIpa;
-  private final AppleConfiguration appleConfiguration;
+  private final DottedVersion iosSdkVersion;
+  private final ApplePlatform platform;
 
   public BundleMergeControlBytes(
-      Bundling rootBundling, Artifact mergedIpa, AppleConfiguration appleConfiguration) {
+      Bundling rootBundling, Artifact mergedIpa, DottedVersion iosSdkVersion,
+      ApplePlatform platform) {
     this.rootBundling = Preconditions.checkNotNull(rootBundling);
     this.mergedIpa = Preconditions.checkNotNull(mergedIpa);
-    this.appleConfiguration = Preconditions.checkNotNull(appleConfiguration);
+    this.iosSdkVersion = iosSdkVersion;
+    this.platform = platform;
   }
 
   @Override
@@ -56,8 +59,8 @@ final class BundleMergeControlBytes extends ByteSource {
             .addAllBundleFile(BundleableFile.toBundleFiles(bundling.getBundleFiles()))
             // TODO(bazel-team): Add rule attribute for specifying targeted device family
             .setMinimumOsVersion(bundling.getMinimumOsVersion().toString())
-            .setSdkVersion(appleConfiguration.getIosSdkVersion().toString())
-            .setPlatform(appleConfiguration.getMultiArchPlatform(PlatformType.IOS).name())
+            .setSdkVersion(iosSdkVersion.toString())
+            .setPlatform(platform.name())
             .setBundleRoot(bundling.getBundleDir());
 
     if (bundling.getBundleInfoplist().isPresent()) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
index 39ed3e564c..7e49b8eea3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/CompilationSupport.java
@@ -69,6 +69,7 @@ import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
 import com.google.devtools.build.lib.rules.apple.AppleToolchain;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.cpp.CcToolchain;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainProvider;
 import com.google.devtools.build.lib.rules.cpp.CppFileTypes;
@@ -264,18 +265,19 @@ public abstract class CompilationSupport {
 
   /** Returns a list of framework search path flags for clang actions. */
   static Iterable<String> commonFrameworkFlags(
-      ObjcProvider provider, AppleConfiguration appleConfiguration) {
-    return Interspersing.beforeEach("-F", commonFrameworkNames(provider, appleConfiguration));
+      ObjcProvider provider, RuleContext ruleContext) {
+    return Interspersing.beforeEach("-F", commonFrameworkNames(provider, ruleContext));
   }
 
   /** Returns a list of frameworks for clang actions. */
   static Iterable<String> commonFrameworkNames(
-      ObjcProvider provider, AppleConfiguration appleConfiguration) {
+      ObjcProvider provider, RuleContext ruleContext) {
+    AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);
     ApplePlatform platform = appleConfiguration.getSingleArchPlatform();
 
     ImmutableList.Builder<String> frameworkNames =
         new ImmutableList.Builder<String>()
-            .add(AppleToolchain.sdkFrameworkDir(platform, appleConfiguration));
+            .add(AppleToolchain.sdkFrameworkDir(platform, ruleContext));
     if (platform.getType() == PlatformType.IOS) {
       // As of sdk8.1, XCTest is in a base Framework dir
       frameworkNames.add(AppleToolchain.platformDeveloperFrameworkDir(appleConfiguration));
@@ -1413,12 +1415,11 @@ public abstract class CompilationSupport {
             .add("--platform")
             .add(appleConfiguration.getSingleArchPlatform().getLowerCaseNameInPlist())
             .add("--sdk_version")
-            .add(
-                appleConfiguration
-                    .getSdkVersionForPlatform(appleConfiguration.getSingleArchPlatform())
+            .add(XcodeConfig.getSdkVersionForPlatform(
+                ruleContext, appleConfiguration.getSingleArchPlatform())
                     .toStringWithMinimumComponents(2))
             .add("--xcode_version")
-            .add(appleConfiguration.getXcodeVersion().toStringWithMinimumComponents(2))
+            .add(XcodeConfig.getXcodeVersion(ruleContext).toStringWithMinimumComponents(2))
             .add("--");
     for (ObjcHeaderThinningInfo info : infos) {
       cmdLine.addJoinPaths(
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDevice.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDevice.java
index 2a0a2142da..769a3b465b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDevice.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDevice.java
@@ -23,9 +23,9 @@ import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.RunfilesProvider;
 import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
-import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.apple.XcodeVersionProperties;
 
 /**
@@ -39,7 +39,6 @@ public final class IosDevice implements RuleConfiguredTargetFactory {
         "This rule is deprecated. Please use the new Apple build rules "
             + "(https://github.com/bazelbuild/rules_apple) to build Apple targets.");
 
-    AppleConfiguration appleConfiguration = context.getFragment(AppleConfiguration.class);
     String iosVersionAttribute =
         context.attributes().get(IosDeviceRule.IOS_VERSION_ATTR_NAME, STRING);
     XcodeVersionProperties xcodeVersionProperties =
@@ -51,8 +50,8 @@ public final class IosDevice implements RuleConfiguredTargetFactory {
     DottedVersion xcodeVersion = null;
     if (xcodeVersionProperties != null && xcodeVersionProperties.getXcodeVersion().isPresent()) {
       xcodeVersion = xcodeVersionProperties.getXcodeVersion().get();
-    } else if (appleConfiguration.getXcodeVersion() != null) {
-      xcodeVersion = appleConfiguration.getXcodeVersion();
+    } else if (XcodeConfig.getXcodeVersion(context) != null) {
+      xcodeVersion = XcodeConfig.getXcodeVersion(context);
     }
 
     DottedVersion iosVersion;
@@ -61,7 +60,7 @@ public final class IosDevice implements RuleConfiguredTargetFactory {
     } else if (xcodeVersionProperties != null) {
       iosVersion = xcodeVersionProperties.getDefaultIosSdkVersion();
     } else {
-      iosVersion = appleConfiguration.getSdkVersionForPlatform(ApplePlatform.IOS_SIMULATOR);
+      iosVersion = XcodeConfig.getSdkVersionForPlatform(context, ApplePlatform.IOS_SIMULATOR);
     }
 
     IosDeviceProvider provider =
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceRule.java
index 4a20d4a41b..ca8d2809c5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceRule.java
@@ -24,6 +24,7 @@ import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
 import com.google.devtools.build.lib.packages.RuleClass;
 import com.google.devtools.build.lib.packages.RuleClass.Builder;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+import com.google.devtools.build.lib.rules.apple.AppleToolchain;
 
 /**
  * Rule definition for ios_device.
@@ -69,7 +70,7 @@ public final class IosDeviceRule implements RuleDefinition {
     return RuleDefinition.Metadata.builder()
         .name("ios_device")
         .factoryClass(IosDevice.class)
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.BaseRule.class, AppleToolchain.RequiresXcodeConfigRule.class)
         .build();
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
index 897deace6a..8526bbcba2 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
@@ -25,10 +25,10 @@ import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
 import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions;
-import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration.ConfigurationDistinguisher;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition;
 import java.io.Serializable;
 import javax.annotation.Nullable;
@@ -67,8 +67,7 @@ public class IosExtension extends ReleaseBundlingTargetFactory {
   @Override
   protected DottedVersion bundleMinimumOsVersion(RuleContext ruleContext) {
     return determineMinimumOsVersion(
-        ruleContext.getFragment(AppleConfiguration.class)
-            .getMinimumOsForPlatformType(PlatformType.IOS),
+        XcodeConfig.getMinimumOsForPlatformType(ruleContext, PlatformType.IOS),
         EXTENSION_MINIMUM_OS_VERSION);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosTest.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosTest.java
index 2c9b337c4e..d1ddc215a0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosTest.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosTest.java
@@ -35,6 +35,7 @@ import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
 import com.google.devtools.build.lib.rules.objc.ObjcCommon.ResourceAttributes;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.LinkedBinary;
@@ -181,7 +182,7 @@ public final class IosTest implements RuleConfiguredTargetFactory {
             common.getObjcProvider(),
             LinkedBinary.LOCAL_AND_DEPENDENCIES,
             bundleFormat,
-            appleConfiguration.getMinimumOsForPlatformType(PlatformType.IOS),
+            XcodeConfig.getMinimumOsForPlatformType(ruleContext, PlatformType.IOS),
             appleConfiguration.getMultiArchPlatform(PlatformType.IOS))
         .registerActions(DsymOutputType.TEST)
         .addFilesToBuild(filesToBuild, Optional.of(DsymOutputType.TEST))
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
index 60a24514e0..219eaa51c7 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
@@ -50,6 +50,7 @@ import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.AppleToolchain;
+import com.google.devtools.build.lib.rules.apple.XcodeConfigRule;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainProvider;
 import com.google.devtools.build.lib.rules.cpp.CppConfiguration;
 import com.google.devtools.build.lib.rules.cpp.CppHelper;
@@ -203,11 +204,10 @@ public class J2ObjcAspect extends NativeAspectClass implements ConfiguredAspectF
                 .exec()
                 .value(Label.parseAbsoluteUnchecked(toolsRepository + "//tools/objc:libtool")))
         .add(
-            attr(":xcode_config", LABEL)
+            attr(XcodeConfigRule.XCODE_CONFIG_ATTR_NAME, LABEL)
                 .allowedRuleClasses("xcode_config")
                 .checkConstraints()
                 .direct_compile_time_input()
-                .cfg(HOST)
                 .value(new AppleToolchain.XcodeConfigLabel(toolsRepository)))
         .add(
             attr("$zipper", LABEL)
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/LegacyCompilationSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/LegacyCompilationSupport.java
index 82de6228ac..bfcf03b992 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/LegacyCompilationSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/LegacyCompilationSupport.java
@@ -57,11 +57,13 @@ import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.collect.nestedset.Order;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
+import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions;
 import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions.AppleBitcodeMode;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.AppleToolchain;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainProvider;
 import com.google.devtools.build.lib.rules.cpp.CppCompileAction.DotdFile;
 import com.google.devtools.build.lib.rules.cpp.CppModuleMap;
@@ -790,6 +792,34 @@ public class LegacyCompilationSupport extends CompilationSupport {
     }
   }
 
+  /**
+   * This method is necessary because
+   * {@link XcodeConfig#getMinimumOsForPlatformType(RuleContext, ApplePlatform.PlatformType)} uses
+   * the configuration of whichever rule it was called from; however, we are interested in the
+   * minimum versions for the dependencies here, which are possibly behind a configuration
+   * transition.
+   *
+   * <p>It's kosher to reach into {@link }AppleConfiguration} this way because we don't touch
+   * anything that may be tainted by data from BUILD files, only the options, which are directly
+   * passed into the configuration loader.
+   */
+  private DottedVersion getExplicitMinimumOsVersion(
+      AppleConfiguration configuration, ApplePlatform.PlatformType platformType) {
+    AppleCommandLineOptions options = configuration.getOptions();
+    switch (platformType) {
+      case IOS:
+        return options.iosMinimumOs;
+      case WATCHOS:
+        return options.watchosMinimumOs;
+      case TVOS:
+        return options.tvosMinimumOs;
+      case MACOS:
+        return options.macosMinimumOs;
+      default:
+        throw new IllegalStateException("Unhandled platform type: " + platformType);
+    }
+  }
+
   /** Returns a list of clang flags used for all link and compile actions executed through clang. */
   private List<String> commonLinkAndCompileFlagsForClang(
       ObjcProvider provider, ObjcConfiguration objcConfiguration,
@@ -819,7 +849,11 @@ public class LegacyCompilationSupport extends CompilationSupport {
       default:
         throw new IllegalArgumentException("Unhandled platform " + platform);
     }
-    DottedVersion minOSVersion = appleConfiguration.getMinimumOsForPlatformType(platform.getType());
+    DottedVersion minOSVersion =
+        getExplicitMinimumOsVersion(appleConfiguration, platform.getType());
+    if (minOSVersion == null) {
+      minOSVersion = XcodeConfig.getMinimumOsForPlatformType(ruleContext, platform.getType());
+    }
     builder.add(minOSVersionArg + "=" + minOSVersion);
 
     if (objcConfiguration.generateDsym()) {
@@ -830,7 +864,7 @@ public class LegacyCompilationSupport extends CompilationSupport {
         .add("-arch", appleConfiguration.getSingleArchitecture())
         .add("-isysroot", AppleToolchain.sdkDir())
         // TODO(bazel-team): Pass framework search paths to Xcodegen.
-        .addAll(commonFrameworkFlags(provider, appleConfiguration))
+        .addAll(commonFrameworkFlags(provider, ruleContext))
         .build();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
index b44cd2dfac..aa6d9b3b01 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBundleLibrary.java
@@ -26,6 +26,7 @@ import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.BundleSupport.ExtraActoolArgs;
 import com.google.devtools.build.lib.rules.objc.ObjcCommon.ResourceAttributes;
 import com.google.devtools.build.lib.rules.objc.TargetDeviceFamily.InvalidFamilyNameException;
@@ -103,7 +104,7 @@ public class ObjcBundleLibrary implements RuleConfiguredTargetFactory {
         .setObjcProvider(common.getObjcProvider())
         .addInfoplistInputFromRule(ruleContext)
         .setIntermediateArtifacts(intermediateArtifacts)
-        .setMinimumOsVersion(appleConfiguration.getMinimumOsForPlatformType(PlatformType.IOS))
+        .setMinimumOsVersion(XcodeConfig.getMinimumOsForPlatformType(ruleContext, PlatformType.IOS))
         .setTargetDeviceFamilies(families)
         .build();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
index bf43087e5a..452b2606ea 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
@@ -25,7 +25,6 @@ import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.packages.BuildType;
-import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures.Variables.StringSequenceBuilder;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures.Variables.VariablesExtension;
@@ -69,7 +68,6 @@ class ObjcVariablesExtension implements VariablesExtension {
   private final Artifact fullyLinkArchive;
   private final IntermediateArtifacts intermediateArtifacts;
   private final BuildConfiguration buildConfiguration;
-  private final AppleConfiguration appleConfiguration;
   private final Set<String> frameworkNames;
   private final ImmutableList<String> libraryNames;
   private final ImmutableSet<Artifact> forceLoadArtifacts;
@@ -100,7 +98,6 @@ class ObjcVariablesExtension implements VariablesExtension {
     this.fullyLinkArchive = fullyLinkArchive;
     this.intermediateArtifacts = intermediateArtifacts;
     this.buildConfiguration = buildConfiguration;
-    this.appleConfiguration = buildConfiguration.getFragment(AppleConfiguration.class);
     this.frameworkNames = frameworkNames;
     this.libraryNames = libraryNames;
     this.forceLoadArtifacts = forceLoadArtifacts;
@@ -158,7 +155,7 @@ class ObjcVariablesExtension implements VariablesExtension {
   private void addFrameworkVariables(CcToolchainFeatures.Variables.Builder builder) {
     StringSequenceBuilder frameworkSequence = new StringSequenceBuilder();
     for (String framework :
-        CompilationSupport.commonFrameworkNames(objcProvider, appleConfiguration)) {
+        CompilationSupport.commonFrameworkNames(objcProvider, ruleContext)) {
       frameworkSequence.addValue(framework);
     }
     builder.addCustomBuiltVariable(FRAMEWORKS_VARIABLE_NAME, frameworkSequence);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
index 75c4b717d6..6aa8f487bc 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
@@ -58,6 +58,7 @@ import com.google.devtools.build.lib.rules.apple.AppleConfiguration.Configuratio
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.BundleSupport.ExtraActoolArgs;
 import com.google.devtools.build.lib.rules.objc.Bundling.Builder;
 import com.google.devtools.build.lib.shell.ShellUtils;
@@ -383,7 +384,7 @@ public final class ReleaseBundlingSupport {
         String.format(
             "%s%s",
             platform.getLowerCaseNameInPlist(),
-            configuration.getSdkVersionForPlatform(platform));
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, platform));
     ruleContext.registerAction(
         ObjcRuleClasses.spawnAppleEnvActionBuilder(configuration, platform)
             .setMnemonic("EnvironmentPlist")
@@ -410,8 +411,6 @@ public final class ReleaseBundlingSupport {
   private NSDictionary automaticEntries() {
     List<Integer> uiDeviceFamily =
         TargetDeviceFamily.UI_DEVICE_FAMILY_VALUES.get(bundleSupport.targetDeviceFamilies());
-    AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);
-
     NSDictionary result = new NSDictionary();
 
     if (uiDeviceFamily != null) {
@@ -420,7 +419,8 @@ public final class ReleaseBundlingSupport {
     result.put("DTPlatformName", platform.getLowerCaseNameInPlist());
     result.put(
         "DTSDKName",
-        platform.getLowerCaseNameInPlist() + appleConfiguration.getSdkVersionForPlatform(platform));
+        platform.getLowerCaseNameInPlist()
+            + XcodeConfig.getSdkVersionForPlatform(ruleContext, platform));
     result.put("CFBundleSupportedPlatforms", new NSArray(NSObject.wrap(platform.getNameInPlist())));
     result.put("MinimumOSVersion", bundling.getMinimumOsVersion().toString());
 
@@ -511,7 +511,7 @@ public final class ReleaseBundlingSupport {
   }
 
   private ImmutableList<String> getDirsToSign() {
-    // The order here is important. The innermost code must singed first.
+    // The order here is important. The innermost code must signed first.
     ImmutableList.Builder<String> dirsToSign = new ImmutableList.Builder<>();
     String bundleDir = ShellUtils.shellEscape(bundling.getBundleDir());
 
@@ -838,7 +838,9 @@ public final class ReleaseBundlingSupport {
         new BundleMergeControlBytes(
             bundling,
             intermediateArtifacts.unprocessedIpa(),
-            ruleContext.getFragment(AppleConfiguration.class));
+            XcodeConfig.getSdkVersionForPlatform(ruleContext, ApplePlatform.IOS_DEVICE),
+            ruleContext.getFragment(AppleConfiguration.class)
+                .getMultiArchPlatform(PlatformType.IOS));
 
     ruleContext.registerAction(
         new BinaryFileWriteAction(
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
index 68acca2432..53820e6281 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
@@ -25,6 +25,7 @@ import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform.PlatformType;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.lib.rules.apple.XcodeConfig;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.LinkedBinary;
 import com.google.devtools.build.lib.rules.test.InstrumentedFilesCollector;
 import com.google.devtools.build.lib.rules.test.InstrumentedFilesProvider;
@@ -107,8 +108,7 @@ public abstract class ReleaseBundlingTargetFactory implements RuleConfiguredTarg
    * configuration).
    */
   protected DottedVersion bundleMinimumOsVersion(RuleContext ruleContext) {
-    return ruleContext.getFragment(AppleConfiguration.class)
-        .getMinimumOsForPlatformType(PlatformType.IOS);
+    return XcodeConfig.getMinimumOsForPlatformType(ruleContext, PlatformType.IOS);
   }
 
   /**