Flip Starlark implementation of cc_toolchain and `apple_cc_toolch…

…ain` rules.

PiperOrigin-RevId: 547510311
Change-Id: I52eae04c2d797803d56c330797191cceadf72901

src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainAttributesProvider.java

@@ -13,7 +13,6 @@
 // limitations under the License.
 package com.google.devtools.build.lib.rules.cpp;
 
-import static com.google.devtools.build.lib.packages.BuildType.NODEP_LABEL;
 import static com.google.devtools.build.lib.packages.Type.BOOLEAN;
 
 import com.google.common.base.Preconditions;
@@ -67,7 +66,6 @@ public class CcToolchainAttributesProvider extends NativeInfo implements HasCcTo
   private final NestedSet<Artifact> arFiles;
   private final NestedSet<Artifact> linkerFiles;
   private final NestedSet<Artifact> dwpFiles;
-  private final Label libcTopAttribute;
   private final NestedSet<Artifact> libc;
   private final TransitiveInfoCollection libcTop;
   private final NestedSet<Artifact> targetLibc;
@@ -105,6 +103,8 @@ public class CcToolchainAttributesProvider extends NativeInfo implements HasCcTo
   private final PackageSpecificationProvider allowlistForLayeringCheck;
   private final PackageSpecificationProvider allowlistForLooseHeaderCheck;
   private final StarlarkFunction ccToolchainBuildVariablesFunc;
+  private final String lateBoundLibc;
+  private final String lateBoundTargetLibc;
 
   public CcToolchainAttributesProvider(
       RuleContext ruleContext,
@@ -141,13 +141,14 @@ public CcToolchainAttributesProvider(
     this.linkerFiles = getFiles(ruleContext, "linker_files");
     this.dwpFiles = getFiles(ruleContext, "dwp_files");
 
-    this.libc = getOptionalFiles(ruleContext, CcToolchainRule.LIBC_TOP_ATTR);
-    this.libcTop = ruleContext.getPrerequisite(CcToolchainRule.LIBC_TOP_ATTR);
+    this.lateBoundLibc = getLateBoundLibc(ruleContext, "libc_top", ":libc_top");
+    this.lateBoundTargetLibc = getLateBoundLibc(ruleContext, "libc_top", ":target_libc_top");
 
-    this.targetLibc = getOptionalFiles(ruleContext, CcToolchainRule.TARGET_LIBC_TOP_ATTR);
-    this.targetLibcTop = ruleContext.getPrerequisite(CcToolchainRule.TARGET_LIBC_TOP_ATTR);
+    this.libc = getOptionalFiles(ruleContext, lateBoundLibc);
+    this.libcTop = ruleContext.getPrerequisite(lateBoundLibc);
 
-    this.libcTopAttribute = ruleContext.attributes().get("libc_top", BuildType.LABEL);
+    this.targetLibc = getOptionalFiles(ruleContext, lateBoundTargetLibc);
+    this.targetLibcTop = ruleContext.getPrerequisite(lateBoundTargetLibc);
 
     this.fullInputsForCrosstool =
         NestedSetBuilder.<Artifact>stableOrder()
@@ -180,8 +181,7 @@ public CcToolchainAttributesProvider(
     this.propellerOptimize =
         ruleContext.getPrerequisite(":propeller_optimize", PropellerOptimizeProvider.PROVIDER);
     this.memprofProfileProvider =
-        ruleContext.getPrerequisite(
-            CcToolchainRule.MEMPROF_PROFILE_ATTR, MemProfProfileProvider.PROVIDER);
+        ruleContext.getPrerequisite(":memprof_profile", MemProfProfileProvider.PROVIDER);
     this.moduleMap = ruleContext.getPrerequisite("module_map");
     this.moduleMapArtifact = ruleContext.getPrerequisiteArtifact("module_map");
     this.zipper = ruleContext.getPrerequisiteArtifact(":zipper");
@@ -217,7 +217,9 @@ public CcToolchainAttributesProvider(
     // TODO(b/65835260): Remove this conditional once j2objc can learn the toolchain type.
     if (ruleContext.attributes().has(CcToolchain.CC_TOOLCHAIN_TYPE_ATTRIBUTE_NAME)) {
       this.toolchainType =
-          ruleContext.attributes().get(CcToolchain.CC_TOOLCHAIN_TYPE_ATTRIBUTE_NAME, NODEP_LABEL);
+          ruleContext
+              .attributes()
+              .get(CcToolchain.CC_TOOLCHAIN_TYPE_ATTRIBUTE_NAME, BuildType.LABEL);
     } else {
       this.toolchainType = null;
     }
@@ -230,6 +232,19 @@ public CcToolchainAttributesProvider(
     this.ccToolchainBuildVariablesFunc = ccToolchainBuildVariablesFunc;
   }
 
+  // This is to avoid Starlark limitation of not being able to have complex logic in configuration
+  // field. The logic here was encapsulated in native cc_toolchain rule's :libc_top's and
+  // :target_libc_top's LateBoundDefault attributes.
+  // In case :libc_top or :target_libc_top were not specified from command line, i.e. grte_top was
+  // not set we will try to use public attributes instead.
+  private static String getLateBoundLibc(
+      RuleContext ruleContext, String attribute, String implicitAttribute) {
+    if (ruleContext.getPrerequisite(implicitAttribute) == null) {
+      return attribute;
+    }
+    return implicitAttribute;
+  }
+
   @Override
   public BuiltinProvider<CcToolchainAttributesProvider> getProvider() {
     return PROVIDER;
@@ -543,10 +558,6 @@ public Label getTargetLibcTopLabel() {
     return getTargetLibcTop() == null ? null : getTargetLibcTop().getLabel();
   }
 
-  public Label getLibcTopAttribute() {
-    return libcTopAttribute;
-  }
-
   public String getCompiler() {
     return compiler;
   }

src/main/starlark/builtins_bzl/common/exports.bzl

@@ -81,8 +81,8 @@ exported_rules = {
     "proto_lang_toolchain": proto_lang_toolchain,
     "+py_runtime": py_runtime,
     "+cc_toolchain_alias": cc_toolchain_alias,
-    "-cc_toolchain": cc_toolchain,
-    "-apple_cc_toolchain": apple_cc_toolchain,
+    "+cc_toolchain": cc_toolchain,
+    "+apple_cc_toolchain": apple_cc_toolchain,
 }
 
 # A list of Starlark functions callable from native rules implementation.

src/test/java/com/google/devtools/build/lib/rules/cpp/CcToolchainTest.java

@@ -474,10 +474,10 @@ public void testXFdoOptimizeNotProvider() throws Exception {
     scratch.file(
         "a/BUILD",
         "cc_toolchain_alias(name = 'b')",
-        "fdo_profile(name='out.xfdo', profile='profile.xfdo')");
+        "genrule(name='profile.xfdo', outs = ['c.txt'], cmd = '')");
     useConfiguration("-c", "opt", "--xbinary_fdo=//a:profile.xfdo");
     assertThat(getConfiguredTarget("//a:b")).isNull();
-    assertContainsEvent("--fdo_profile/--xbinary_fdo input needs to be an fdo_profile rule");
+    assertContainsEvent("does not have mandatory providers: 'FdoProfileInfo'");
   }
 
   @Test