Don't crash on duplicate type parameter declarations

PiperOrigin-RevId: 504070824

4 files changed, 38 insertions, 14 deletions

diff --git a/java/com/google/turbine/binder/HierarchyBinder.java b/java/com/google/turbine/binder/HierarchyBinder.java
index ac2c840..3117d4e 100644
--- a/java/com/google/turbine/binder/HierarchyBinder.java
+++ b/java/com/google/turbine/binder/HierarchyBinder.java
@@ -34,6 +34,7 @@ import com.google.turbine.model.TurbineTyKind;
 import com.google.turbine.tree.Tree;
 import com.google.turbine.tree.Tree.ClassTy;
 import java.util.ArrayDeque;
+import java.util.LinkedHashMap;
 import org.jspecify.nullness.Nullable;
 
 /** Type hierarchy binding. */
@@ -109,13 +110,17 @@ public class HierarchyBinder {
       }
     }
 
-    ImmutableMap.Builder<String, TyVarSymbol> typeParameters = ImmutableMap.builder();
+    LinkedHashMap<String, TyVarSymbol> typeParameters = new LinkedHashMap<>();
     for (Tree.TyParam p : decl.typarams()) {
-      typeParameters.put(p.name().value(), new TyVarSymbol(origin, p.name().value()));
+      TyVarSymbol existing =
+          typeParameters.putIfAbsent(p.name().value(), new TyVarSymbol(origin, p.name().value()));
+      if (existing != null) {
+        log.error(p.position(), ErrorKind.DUPLICATE_DECLARATION, p.name());
+      }
     }
 
     return new SourceHeaderBoundClass(
-        base, superclass, interfaces.build(), typeParameters.buildOrThrow());
+        base, superclass, interfaces.build(), ImmutableMap.copyOf(typeParameters));
   }
 
   /**
diff --git a/java/com/google/turbine/binder/TypeBinder.java b/java/com/google/turbine/binder/TypeBinder.java
index 39c7089..edfacba 100644
--- a/java/com/google/turbine/binder/TypeBinder.java
+++ b/java/com/google/turbine/binder/TypeBinder.java
@@ -64,6 +64,7 @@ import com.google.turbine.types.Deannotate;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -627,7 +628,7 @@ public class TypeBinder {
   /** Bind type parameter types. */
   private ImmutableMap<TyVarSymbol, TyVarInfo> bindTyParams(
       ImmutableList<Tree.TyParam> trees, CompoundScope scope, Map<String, TyVarSymbol> symbols) {
-    ImmutableMap.Builder<TyVarSymbol, TyVarInfo> result = ImmutableMap.builder();
+    LinkedHashMap<TyVarSymbol, TyVarInfo> result = new LinkedHashMap<>();
     for (Tree.TyParam tree : trees) {
       // `symbols` is constructed to guarantee the requireNonNull call is safe.
       TyVarSymbol sym = requireNonNull(symbols.get(tree.name().value()));
@@ -636,12 +637,16 @@ public class TypeBinder {
         bounds.add(bindTy(scope, bound));
       }
       ImmutableList<AnnoInfo> annotations = bindAnnotations(scope, tree.annos());
-      result.put(
-          sym,
-          new TyVarInfo(
-              IntersectionTy.create(bounds.build()), /* lowerBound= */ null, annotations));
+      TyVarInfo existing =
+          result.putIfAbsent(
+              sym,
+              new TyVarInfo(
+                  IntersectionTy.create(bounds.build()), /* lowerBound= */ null, annotations));
+      if (existing != null) {
+        log.error(tree.position(), ErrorKind.DUPLICATE_DECLARATION, tree.name());
+      }
     }
-    return result.buildOrThrow();
+    return ImmutableMap.copyOf(result);
   }
 
   private List<MethodInfo> bindMethods(
@@ -669,7 +674,8 @@ public class TypeBinder {
       for (Tree.TyParam pt : t.typarams()) {
         builder.put(pt.name().value(), new TyVarSymbol(sym, pt.name().value()));
       }
-      typeParameters = builder.buildOrThrow();
+      // errors for duplicates are reported in bindTyParams
+      typeParameters = builder.buildKeepingLast();
     }
 
     // type parameters can refer to each other in f-bounds, so update the scope first
diff --git a/javatests/com/google/turbine/binder/BinderErrorTest.java b/javatests/com/google/turbine/binder/BinderErrorTest.java
index 6766470..1a83f0d 100644
--- a/javatests/com/google/turbine/binder/BinderErrorTest.java
+++ b/javatests/com/google/turbine/binder/BinderErrorTest.java
@@ -768,9 +768,7 @@ public class BinderErrorTest {
           "@interface Test {}",
         },
         {
-          "<>:3: error: missing required annotation argument: value",
-          "@Retention",
-          "^",
+          "<>:3: error: missing required annotation argument: value", "@Retention", "^",
         },
       },
       {
@@ -958,6 +956,21 @@ public class BinderErrorTest {
           "                                         ^",
         },
       },
+      {
+        {
+          "class T<X, X> {", //
+          "  <Y, Y> void f() {}",
+          "}",
+        },
+        {
+          "<>:1: error: duplicate declaration of X",
+          "class T<X, X> {",
+          "           ^",
+          "<>:2: error: duplicate declaration of Y",
+          "  <Y, Y> void f() {}",
+          "      ^",
+        },
+      },
     };
     return Arrays.asList((Object[][]) testCases);
   }
diff --git a/pom.xml b/pom.xml
index a2bf088..c96551f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -31,7 +31,7 @@
 
   <properties>
     <asm.version>9.4</asm.version>
-    <guava.version>31.0.1-jre</guava.version>
+    <guava.version>31.1-jre</guava.version>
     <errorprone.version>2.16</errorprone.version>
     <maven-javadoc-plugin.version>3.3.1</maven-javadoc-plugin.version>
     <maven-source-plugin.version>3.2.1</maven-source-plugin.version>