Have SkylarkAttr expose whether a skylark rule class attribute type is configurable or not.

--
MOS_MIGRATED_REVID=124565334

1 files changed, 24 insertions, 4 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/SkylarkAttr.java b/src/main/java/com/google/devtools/build/lib/rules/SkylarkAttr.java
index bdc9cb9b6f..feb73e7043 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/SkylarkAttr.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/SkylarkAttr.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.lib.rules;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.packages.Attribute;
@@ -42,9 +43,13 @@ import com.google.devtools.build.lib.syntax.Type.ConversionException;
 import com.google.devtools.build.lib.syntax.UserDefinedFunction;
 import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.FileTypeSet;
+import com.google.devtools.build.lib.util.Preconditions;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+
+import javax.annotation.Nullable;
 
 /**
  * A helper class to provide Attr module in Skylark.
@@ -249,15 +254,32 @@ public final class SkylarkAttr {
     }
   }
 
+  private static final Map<Type<?>, String> whyNotConfigurable =
+      ImmutableMap.<Type<?>, String>builder()
+          .put(BuildType.LICENSE,
+              "loading phase license checking logic assumes non-configurable values")
+          .put(BuildType.OUTPUT, "output paths are part of the static graph structure")
+          .build();
+
+  /**
+   * If the given attribute type is non-configurable, returns the reason why. Otherwise, returns
+   * {@code null}.
+   */
+  @Nullable
+  public static String maybeGetNonConfigurableReason(Type<?> type) {
+    return whyNotConfigurable.get(type);
+  }
+
   private static Descriptor createNonconfigurableAttrDescriptor(
       SkylarkDict<String, Object> kwargs,
       Type<?> type,
-      String whyNotConfigurable,
       FuncallExpression ast,
       Environment env) throws EvalException {
+    String whyNotConfigurableReason =
+        Preconditions.checkNotNull(maybeGetNonConfigurableReason(type), type);
     try {
       return new Descriptor(
-          createAttribute(type, kwargs, ast, env).nonconfigurable(whyNotConfigurable));
+          createAttribute(type, kwargs, ast, env).nonconfigurable(whyNotConfigurableReason));
     } catch (ConversionException e) {
       throw new EvalException(ast.getLocation(), e.getMessage());
     }
@@ -725,7 +747,6 @@ public final class SkylarkAttr {
               EvalUtils.<String, Object>optionMap(
                   env, DEFAULT_ARG, defaultO, MANDATORY_ARG, mandatory),
               BuildType.OUTPUT,
-              "output paths are part of the static graph structure",
               ast,
               env);
         }
@@ -875,7 +896,6 @@ public final class SkylarkAttr {
               EvalUtils.<String, Object>optionMap(
                   env, DEFAULT_ARG, defaultO, MANDATORY_ARG, mandatory),
               BuildType.LICENSE,
-              "loading phase license checking logic assumes non-configurable values",
               ast,
               env);
         }