Take into account repository mapping when processing labels inside BUILD files within external repositories.

For example:
a/BUILD
genrule(
  name = "a",
  srcs = ["@x//:x.txt"],
  outs = ["result.txt"],
  cmd = "echo hello > \$(location result.txt)"
)

If the main workspace file references that repository with a rule:
local_repository(
  name = "other_repo",
  path = "../a",
  repo_mapping = {"@x" : "@y"}
)

Then when a/BUILD is evaluated, the string "@x//:x.txt" will be turned into a Label "@y//:x.txt"

RELNOTES: None
PiperOrigin-RevId: 201562148

4 files changed, 127 insertions, 37 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index 6f238429eb..91106b272c 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -533,12 +533,32 @@ public final class Label
     }
   )
   public Label getRelative(String relName) throws LabelSyntaxException {
+    return getRelativeWithRemapping(relName, /* repositoryMapping= */ ImmutableMap.of());
+  }
+
+  /**
+   * Resolves a relative or absolute label name. If given name is absolute, then this method calls
+   * {@link #parseAbsolute}. Otherwise, it calls {@link #getLocalTargetLabel}.
+   *
+   * <p>For example: {@code :quux} relative to {@code //foo/bar:baz} is {@code //foo/bar:quux};
+   * {@code //wiz:quux} relative to {@code //foo/bar:baz} is {@code //wiz:quux};
+   * {@code @repo//foo:bar} relative to anything will be {@code @repo//foo:bar} if {@code @repo} is
+   * not in {@code repositoryMapping} but will be {@code @other_repo//foo:bar} if there is an entry
+   * {@code @repo -> @other_repo} in {@code repositoryMapping}
+   *
+   * @param relName the relative label name; must be non-empty
+   * @param repositoryMapping the map of local repository names in external repository to global
+   *     repository names in main repo; can be empty, but not null
+   */
+  public Label getRelativeWithRemapping(
+      String relName, ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
+      throws LabelSyntaxException {
     if (relName.length() == 0) {
       throw new LabelSyntaxException("empty package-relative label");
     }
 
     if (LabelValidator.isAbsolute(relName)) {
-      return resolveRepositoryRelative(parseAbsolute(relName, false));
+      return resolveRepositoryRelative(parseAbsolute(relName, false, repositoryMapping));
     } else if (relName.equals(":")) {
       throw new LabelSyntaxException("':' is not a valid package-relative label");
     } else if (relName.charAt(0) == ':') {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BuildType.java b/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
index 96042edbd0..d7811acc32 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
@@ -22,6 +22,7 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.packages.License.DistributionType;
 import com.google.devtools.build.lib.packages.License.LicenseParsingException;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
@@ -145,7 +146,7 @@ public final class BuildType {
    * <p>The caller is responsible for casting the returned value appropriately.
    */
   public static <T> Object selectableConvert(
-      Type type, Object x, Object what, @Nullable Label context)
+      Type<T> type, Object x, Object what, LabelConversionContext context)
       throws ConversionException {
     if (x instanceof com.google.devtools.build.lib.syntax.SelectorList) {
       return new SelectorList<T>(
@@ -196,6 +197,31 @@ public final class BuildType {
     }
   }
 
+  /** Context in which to evaluate a label with repository remappings */
+  public static class LabelConversionContext {
+    private final Label label;
+    private final ImmutableMap<RepositoryName, RepositoryName> repositoryMapping;
+
+    public LabelConversionContext(
+        Label label, ImmutableMap<RepositoryName, RepositoryName> repositoryMapping) {
+      this.label = label;
+      this.repositoryMapping = repositoryMapping;
+    }
+
+    public Label getLabel() {
+      return label;
+    }
+
+    public ImmutableMap<RepositoryName, RepositoryName> getRepositoryMapping() {
+      return repositoryMapping;
+    }
+
+    @Override
+    public String toString() {
+      return label.toString();
+    }
+  }
+
   private static class LabelType extends Type<Label> {
     private final LabelClass labelClass;
 
@@ -236,10 +262,24 @@ public final class BuildType {
         return (Label) x;
       }
       try {
-        if (x instanceof String && context == null) {
+        if (!(x instanceof String)) {
+          throw new ConversionException(Type.STRING, x, what);
+        }
+        // TODO(b/110101445): check if context is ever actually null
+        if (context == null) {
           return Label.parseAbsolute((String) x, false);
+        // TODO(b/110308446): remove instances of context being a Label
+        } else if (context instanceof Label) {
+          return ((Label) context).getRelative(STRING.convert(x, what, context));
+        } else if (context instanceof LabelConversionContext) {
+          LabelConversionContext labelConversionContext = (LabelConversionContext) context;
+          return labelConversionContext
+              .getLabel()
+              .getRelativeWithRemapping(
+                  STRING.convert(x, what, context), labelConversionContext.getRepositoryMapping());
+        } else {
+          throw new ConversionException("invalid context '" + context + "' in " + what);
         }
-        return ((Label) context).getRelative(STRING.convert(x, what, context));
       } catch (LabelSyntaxException e) {
         throw new ConversionException("invalid label '" + x + "' in "
             + what + ": " + e.getMessage());
@@ -259,7 +299,7 @@ public final class BuildType {
     public static <ValueT> LabelKeyedDictType<ValueT> create(Type<ValueT> valueType) {
       Preconditions.checkArgument(
           valueType.getLabelClass() == LabelClass.NONE
-          || valueType.getLabelClass() == LabelClass.DEPENDENCY,
+              || valueType.getLabelClass() == LabelClass.DEPENDENCY,
           "Values associated with label keys must not be labels themselves.");
       return new LabelKeyedDictType<>(valueType);
     }
@@ -428,16 +468,22 @@ public final class BuildType {
       }
       try {
         // Enforce value is relative to the context.
-        Label currentRule = (Label) context;
-        Label result = currentRule.getRelative(value);
+        Label currentRule;
+        ImmutableMap<RepositoryName, RepositoryName> repositoryMapping = ImmutableMap.of();
+        if (context instanceof LabelConversionContext) {
+          currentRule = ((LabelConversionContext) context).getLabel();
+          repositoryMapping = ((LabelConversionContext) context).getRepositoryMapping();
+        } else {
+          throw new ConversionException("invalid context '" + context + "' in " + what);
+        }
+        Label result = currentRule.getRelativeWithRemapping(value, repositoryMapping);
         if (!result.getPackageIdentifier().equals(currentRule.getPackageIdentifier())) {
           throw new ConversionException("label '" + value + "' is not in the current package");
         }
         return result;
       } catch (LabelSyntaxException e) {
         throw new ConversionException(
-            "illegal output file name '" + value + "' in rule " + context + ": "
-            + e.getMessage());
+            "illegal output file name '" + value + "' in rule " + context + ": " + e.getMessage());
       }
     }
   }
@@ -452,8 +498,9 @@ public final class BuildType {
     private final List<Selector<T>> elements;
 
     @VisibleForTesting
-    SelectorList(List<Object> x, Object what, @Nullable Label context,
-        Type<T> originalType) throws ConversionException {
+    SelectorList(
+        List<Object> x, Object what, @Nullable LabelConversionContext context, Type<T> originalType)
+        throws ConversionException {
       if (x.size() > 1 && originalType.concat(ImmutableList.<T>of()) == null) {
         throw new ConversionException(
             String.format("type '%s' doesn't support select concatenation", originalType));
@@ -500,11 +547,11 @@ public final class BuildType {
     public Set<Label> getKeyLabels() {
       ImmutableSet.Builder<Label> keys = ImmutableSet.builder();
       for (Selector<T> selector : getSelectors()) {
-         for (Label label : selector.getEntries().keySet()) {
-           if (!Selector.isReservedLabel(label)) {
-             keys.add(label);
-           }
-         }
+        for (Label label : selector.getEntries().keySet()) {
+          if (!Selector.isReservedLabel(label)) {
+            keys.add(label);
+          }
+        }
       }
       return keys.build();
     }
@@ -550,19 +597,24 @@ public final class BuildType {
     private final String noMatchError;
     private final boolean hasDefaultCondition;
 
-    /**
-     * Creates a new Selector using the default error message when no conditions match.
-     */
-    Selector(ImmutableMap<?, ?> x, Object what, @Nullable Label context, Type<T> originalType)
+    /** Creates a new Selector using the default error message when no conditions match. */
+    Selector(
+        ImmutableMap<?, ?> x,
+        Object what,
+        @Nullable LabelConversionContext context,
+        Type<T> originalType)
         throws ConversionException {
       this(x, what, context, originalType, "");
     }
 
-    /**
-     * Creates a new Selector with a custom error message for when no conditions match.
-     */
-    Selector(ImmutableMap<?, ?> x, Object what, @Nullable Label context, Type<T> originalType,
-        String noMatchError) throws ConversionException {
+    /** Creates a new Selector with a custom error message for when no conditions match. */
+    Selector(
+        ImmutableMap<?, ?> x,
+        Object what,
+        @Nullable LabelConversionContext context,
+        Type<T> originalType,
+        String noMatchError)
+        throws ConversionException {
       this.originalType = originalType;
       LinkedHashMap<Label, T> result = Maps.newLinkedHashMapWithExpectedSize(x.size());
       ImmutableSet.Builder<Label> defaultValuesBuilder = ImmutableSet.builder();
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Package.java b/src/main/java/com/google/devtools/build/lib/packages/Package.java
index d6f7944288..3d84851a22 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Package.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Package.java
@@ -926,6 +926,11 @@ public class Package {
       return this;
     }
 
+    /** Get the repository mapping for this package */
+    ImmutableMap<RepositoryName, RepositoryName> getRepositoryMapping() {
+      return this.repositoryMapping;
+    }
+
     /**
      * Sets the name of this package's BUILD file.
      */
diff --git a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
index fba4c92a65..15349b10a3 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/RuleClass.java
@@ -36,11 +36,13 @@ import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.events.NullEventHandler;
 import com.google.devtools.build.lib.packages.Attribute.SkylarkComputedDefaultTemplate;
 import com.google.devtools.build.lib.packages.Attribute.SkylarkComputedDefaultTemplate.CannotPrecomputeDefaultsException;
+import com.google.devtools.build.lib.packages.BuildType.LabelConversionContext;
 import com.google.devtools.build.lib.packages.BuildType.SelectorList;
 import com.google.devtools.build.lib.packages.ConfigurationFragmentPolicy.MissingFragmentPolicy;
 import com.google.devtools.build.lib.packages.RuleClass.Builder.RuleClassType;
@@ -1766,7 +1768,8 @@ public class RuleClass {
       EventHandler eventHandler)
       throws InterruptedException, CannotPrecomputeDefaultsException {
     BitSet definedAttrIndices =
-        populateDefinedRuleAttributeValues(rule, attributeValues, eventHandler);
+        populateDefinedRuleAttributeValues(
+            rule, pkgBuilder.getRepositoryMapping(), attributeValues, eventHandler);
     populateDefaultRuleAttributeValues(rule, pkgBuilder, definedAttrIndices, eventHandler);
     // Now that all attributes are bound to values, collect and store configurable attribute keys.
     populateConfigDependenciesAttribute(rule);
@@ -1779,12 +1782,15 @@ public class RuleClass {
    * <p>Handles the special cases of the attribute named {@code "name"} and attributes with value
    * {@link Runtime#NONE}.
    *
-   * <p>Returns a bitset {@code b} where {@code b.get(i)} is {@code true} if this method set a
-   * value for the attribute with index {@code i} in this {@link RuleClass}. Errors are reported
-   * on {@code eventHandler}.
+   * <p>Returns a bitset {@code b} where {@code b.get(i)} is {@code true} if this method set a value
+   * for the attribute with index {@code i} in this {@link RuleClass}. Errors are reported on {@code
+   * eventHandler}.
    */
   private <T> BitSet populateDefinedRuleAttributeValues(
-      Rule rule, AttributeValues<T> attributeValues, EventHandler eventHandler) {
+      Rule rule,
+      ImmutableMap<RepositoryName, RepositoryName> repositoryMapping,
+      AttributeValues<T> attributeValues,
+      EventHandler eventHandler) {
     BitSet definedAttrIndices = new BitSet();
     for (T attributeAccessor : attributeValues.getAttributeAccessors()) {
       String attributeName = attributeValues.getName(attributeAccessor);
@@ -1809,7 +1815,8 @@ public class RuleClass {
       Object nativeAttributeValue;
       if (attributeValues.valuesAreBuildLanguageTyped()) {
         try {
-          nativeAttributeValue = convertFromBuildLangType(rule, attr, attributeValue);
+          nativeAttributeValue =
+              convertFromBuildLangType(rule, attr, attributeValue, repositoryMapping);
         } catch (ConversionException e) {
           rule.reportError(String.format("%s: %s", rule.getLabel(), e.getMessage()), eventHandler);
           continue;
@@ -2105,13 +2112,19 @@ public class RuleClass {
    * <p>Throws {@link ConversionException} if the conversion fails, or if {@code buildLangValue} is
    * a selector expression but {@code attr.isConfigurable()} is {@code false}.
    */
-  private static Object convertFromBuildLangType(Rule rule, Attribute attr, Object buildLangValue)
+  private static Object convertFromBuildLangType(
+      Rule rule,
+      Attribute attr,
+      Object buildLangValue,
+      ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
       throws ConversionException {
-    Object converted = BuildType.selectableConvert(
-        attr.getType(),
-        buildLangValue,
-        new AttributeConversionContext(attr.getName(), rule.getRuleClass()),
-        rule.getLabel());
+    LabelConversionContext context = new LabelConversionContext(rule.getLabel(), repositoryMapping);
+    Object converted =
+        BuildType.selectableConvert(
+            attr.getType(),
+            buildLangValue,
+            new AttributeConversionContext(attr.getName(), rule.getRuleClass()),
+            context);
 
     if ((converted instanceof SelectorList<?>) && !attr.isConfigurable()) {
       throw new ConversionException(