Move interface so building to action configs

This cl moves the conditional building of interface libraries from LinkCommandLine to action configs and features. It provides link_dynamic_library.sh to keep blaze backwards compatible. The script and related code can be deleted once all crosstools are updated.

RELNOTES: No.

--
MOS_MIGRATED_REVID=135799041

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

@@ -56,6 +56,7 @@
  * Implementation for the cc_toolchain rule.
  */
 public class CcToolchain implements RuleConfiguredTargetFactory {
+
   /**
    * This file (found under the sysroot) may be unconditionally included in every C/C++ compilation.
    */
@@ -198,6 +199,8 @@ public ConfiguredTarget create(RuleContext ruleContext)
           "FDO_DIR", cppConfiguration.getFdoInstrument().getPathString()));
     }
 
+    Artifact linkDynamicLibraryTool = getLinkDynamicLibraryTool(ruleContext);
+
     CcToolchainProvider provider =
         new CcToolchainProvider(
             cppConfiguration,
@@ -220,6 +223,7 @@ public ConfiguredTarget create(RuleContext ruleContext)
             getBuildVariables(ruleContext),
             getBuiltinIncludes(ruleContext),
             coverageEnvironment.build(),
+            linkDynamicLibraryTool,
             getEnvironment(ruleContext));
     RuleConfiguredTargetBuilder builder =
         new RuleConfiguredTargetBuilder(ruleContext)
@@ -250,6 +254,10 @@ public NestedSet<TargetLicense> getTransitiveLicenses() {
     return builder.build();
   }
 
+  private Artifact getLinkDynamicLibraryTool(RuleContext ruleContext) {
+    return ruleContext.getPrerequisiteArtifact("$link_dynamic_library_tool", Mode.TARGET);
+  }
+
   private ImmutableList<Artifact> getBuiltinIncludes(RuleContext ruleContext) {
     ImmutableList.Builder<Artifact> result = ImmutableList.builder();
     for (Artifact artifact : inputsForLibc(ruleContext)) {
@@ -285,6 +293,7 @@ protected NestedSet<Artifact> fullInputsForLink(
     return NestedSetBuilder.<Artifact>stableOrder()
         .addTransitive(link)
         .addTransitive(AnalysisUtils.getMiddlemanFor(ruleContext, ":libc_top"))
+        .add(getLinkDynamicLibraryTool(ruleContext))
         .add(
             ruleContext
                 .getAnalysisEnvironment()

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

@@ -1149,9 +1149,12 @@ public boolean isEnabled(String feature) {
       return enabledFeatureNames.contains(feature);
     }
 
-    /**
-     * @return whether an action config for the blaze action with the given name is enabled.
-     */
+    /** @return true if tool_path in action_config points to a real tool, not a dummy placeholder */
+    public boolean hasConfiguredLinkerPathInActionConfig() {
+      return isEnabled("has_configured_linker_path");
+    }
+
+    /** @return whether an action config for the blaze action with the given name is enabled. */
     boolean actionIsConfigured(String actionName) {
       return enabledActionConfigActionNames.contains(actionName);
     }

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

@@ -25,19 +25,15 @@
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.vfs.PathFragment;
-
 import java.util.Map;
-
 import javax.annotation.Nullable;
 
 /**
  * Information about a C++ compiler used by the <code>cc_*</code> rules.
  */
 @Immutable
 public final class CcToolchainProvider implements TransitiveInfoProvider {
-  /**
-   * An empty toolchain to be returned in the error case (instead of null).
-   */
+  /** An empty toolchain to be returned in the error case (instead of null). */
   public static final CcToolchainProvider EMPTY_TOOLCHAIN_IS_ERROR =
       new CcToolchainProvider(
           null,
@@ -60,6 +56,7 @@ public final class CcToolchainProvider implements TransitiveInfoProvider {
           ImmutableMap.<String, String>of(),
           ImmutableList.<Artifact>of(),
           NestedSetBuilder.<Pair<String, String>>emptySet(Order.COMPILE_ORDER),
+          null,
           ImmutableMap.<String, String>of());
 
   @Nullable private final CppConfiguration cppConfiguration;
@@ -82,6 +79,7 @@ public final class CcToolchainProvider implements TransitiveInfoProvider {
   private final ImmutableMap<String, String> buildVariables;
   private final ImmutableList<Artifact> builtinIncludeFiles;
   private final NestedSet<Pair<String, String>> coverageEnvironment;
+  @Nullable private final Artifact linkDynamicLibraryTool;
   private final ImmutableMap<String, String> environment;
 
   public CcToolchainProvider(
@@ -105,6 +103,7 @@ public CcToolchainProvider(
       Map<String, String> buildVariables,
       ImmutableList<Artifact> builtinIncludeFiles,
       NestedSet<Pair<String, String>> coverageEnvironment,
+      Artifact linkDynamicLibraryTool,
       ImmutableMap<String, String> environment) {
     this.cppConfiguration = cppConfiguration;
     this.crosstool = Preconditions.checkNotNull(crosstool);
@@ -126,6 +125,7 @@ public CcToolchainProvider(
     this.buildVariables = ImmutableMap.copyOf(buildVariables);
     this.builtinIncludeFiles = builtinIncludeFiles;
     this.coverageEnvironment = coverageEnvironment;
+    this.linkDynamicLibraryTool = linkDynamicLibraryTool;
     this.environment = environment;
   }
 
@@ -283,4 +283,12 @@ public NestedSet<Pair<String, String>> getCoverageEnvironment() {
   public ImmutableMap<String, String> getEnvironment() {
     return environment;
   }
+
+  /**
+   * Returns the tool which should be used for linking dynamic libraries, or in case it's not
+   * specified by the crosstool this will be @tools_repository/tools/cpp:link_dynamic_library
+   */
+  public Artifact getLinkDynamicLibraryTool() {
+    return linkDynamicLibraryTool;
+  }
 }

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

@@ -75,12 +75,16 @@ public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
         .add(attr("module_map", LABEL).legacyAllowAnyFileType().cfg(HOST))
         .add(attr("supports_param_files", BOOLEAN).value(true))
         .add(attr("supports_header_parsing", BOOLEAN).value(false))
+        .add(
+            attr("$link_dynamic_library_tool", LABEL)
+                .value(env.getToolsLabel("//tools/cpp:link_dynamic_library")))
         // TODO(bazel-team): Should be using the TARGET configuration.
         .add(attr(":libc_top", LABEL).cfg(HOST).value(LIBC_TOP))
-        .add(attr(":lipo_context_collector", LABEL)
-            .cfg(LipoTransition.LIPO_COLLECTOR)
-            .value(CppRuleClasses.LIPO_CONTEXT_COLLECTOR)
-            .skipPrereqValidatorCheck())
+        .add(
+            attr(":lipo_context_collector", LABEL)
+                .cfg(LipoTransition.LIPO_COLLECTOR)
+                .value(CppRuleClasses.LIPO_CONTEXT_COLLECTOR)
+                .skipPrereqValidatorCheck())
         .build();
   }