Refactoring: Types report what class of labels they contain.

Currently label-type attributes are detected in many places across the
codebase by simply reference-comparing against each of the label types.
This CL aims to generalize most of these cases, moving the encoding of
this logic into a single place (Type/BuildType itself). Not all of these
cases can be made general without further refactoring, and some perhaps
shouldn't be - serialization and Skylark rule context, for example, need
to do exotic things based on the type. But most sites can avoid having to
enumerate all the types they work with explicitly.

This causes LABEL_DICT_UNARY to start being treated like the other label
types, which means that CcToolchainSuiteRule and JavaRuntimeSuiteRule
need to include a set of allowed file types (none, in their case).
Skylark will continue treating it as a dictionary from String to Label
in its rule context, however, to avoid visible behavior changes.

--
PiperOrigin-RevId: 147471542
MOS_MIGRATED_REVID=147471542

1 files changed, 16 insertions, 13 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/constraints/ConstraintSemantics.java b/src/main/java/com/google/devtools/build/lib/analysis/constraints/ConstraintSemantics.java
index 86d736d60a..33f7d348f6 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/constraints/ConstraintSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/constraints/ConstraintSemantics.java
@@ -36,6 +36,8 @@ import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.RuleClass;
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.syntax.Type;
+import com.google.devtools.build.lib.syntax.Type.LabelClass;
+import com.google.devtools.build.lib.syntax.Type.LabelVisitor;
 import com.google.devtools.build.lib.util.Preconditions;
 
 import java.util.Collection;
@@ -739,7 +741,7 @@ public class ConstraintSemantics {
     AttributeMap attributes = ruleContext.attributes();
     for (String attr : attributes.getAttributeNames()) {
       Attribute attrDef = attributes.getAttributeDefinition(attr);
-      if ((attrDef.getType() != BuildType.LABEL && attrDef.getType() != BuildType.LABEL_LIST)
+      if (attrDef.getType().getLabelClass() != LabelClass.DEPENDENCY
           || attrDef.skipConstraintsOverride()) {
         continue;
       }
@@ -819,21 +821,22 @@ public class ConstraintSemantics {
    * Adds all label values from the given select to the given set. Automatically handles different
    * value types (e.g. labels vs. label lists).
    */
-  private static void addSelectValuesToSet(BuildType.Selector<?> select, Set<Label> set) {
+  private static void addSelectValuesToSet(BuildType.Selector<?> select, final Set<Label> set) {
     Type<?> type = select.getOriginalType();
-    if (type == BuildType.LABEL || type == BuildType.NODEP_LABEL) {
-      set.addAll(((BuildType.Selector<Label>) select).getEntries().values());
-    } else if (type == BuildType.LABEL_LIST ||  type == BuildType.NODEP_LABEL_LIST) {
-      for (List<Label> labels : ((BuildType.Selector<List<Label>>) select).getEntries().values()) {
-        set.addAll(labels);
+    LabelVisitor visitor = new LabelVisitor() {
+      @Override
+      public void visit(Label label) {
+        set.add(label);
       }
-    } else if (type == BuildType.LABEL_DICT_UNARY) {
-      for (Map<String, Label> mapEntry :
-          ((BuildType.Selector<Map<String, Label>>) select).getEntries().values()) {
-        set.addAll(mapEntry.values());
+    };
+    for (Object value : select.getEntries().values()) {
+      try {
+        type.visitLabels(visitor, value);
+      } catch (InterruptedException ex) {
+        // Because the LabelVisitor does not throw InterruptedException, it should not be thrown
+        // by visitLabels here.
+        throw new AssertionError(ex);
       }
-    } else {
-      throw new IllegalStateException("Expected a label-based type for this select");
     }
   }
 }