Rule classes cannot request duplicate toolchains.
PiperOrigin-RevId: 167861778
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
index f9ae4cf..ce8405b 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/AspectFunction.java
@@ -17,6 +17,7 @@
import com.google.common.base.Supplier;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.actions.ActionAnalysisMetadata;
import com.google.devtools.build.lib.actions.ActionLookupValue;
import com.google.devtools.build.lib.analysis.AliasProvider;
@@ -275,7 +276,7 @@
// Determine what toolchains are needed by this target.
ToolchainContext toolchainContext;
try {
- ImmutableList<Label> requiredToolchains = aspect.getDefinition().getRequiredToolchains();
+ ImmutableSet<Label> requiredToolchains = aspect.getDefinition().getRequiredToolchains();
toolchainContext =
ToolchainUtil.createToolchainContext(
env,