Don't crash when someone declares a StringBuffer using var.

PiperOrigin-RevId: 449835264
google · May 19, 2022 · 97a7dbc · 97a7dbc
1 parent 9ff2d42
commit 97a7dbc
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Showing 2 changed files with 30 additions and 5 deletions.
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java b/core/src/main/java/com/google/errorprone/bugpatterns/JdkObsolete.java
@@ -60,6 +60,7 @@
 import com.sun.tools.javac.code.Symbol.VarSymbol;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
+import com.sun.tools.javac.util.Position;
 import java.util.Optional;
 import javax.annotation.Nullable;
 
@@ -344,11 +345,13 @@ public Void visitIdentifier(IdentifierTree tree, Void unused) {
     if (escape[0]) {
       return Optional.empty();
     }
-    return Optional.of(
-        SuggestedFix.builder()
-            .replace(newClassTree.getIdentifier(), "StringBuilder")
-            .replace(varTree.getType(), "StringBuilder")
-            .build());
+    SuggestedFix.Builder fix =
+        SuggestedFix.builder().replace(newClassTree.getIdentifier(), "StringBuilder");
+    if (ASTHelpers.getStartPosition(varTree.getType()) != Position.NOPOS) {
+      // If the variable is declared with `var`, there's no declaration type to change
+      fix = fix.replace(varTree.getType(), "StringBuilder");
+    }
+    return Optional.of(fix.build());
   }
 
   private static TreePath findEnclosingMethod(VisitorState state) {

diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/JdkObsoleteTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/JdkObsoleteTest.java
@@ -161,6 +161,28 @@ public void stringBufferRefactoringTest() {
         .doTest();
   }
 
+  @Test
+  public void stringBufferRefactoringTest_usingVar() {
+    BugCheckerRefactoringTestHelper.newInstance(JdkObsolete.class, getClass())
+        .addInputLines(
+            "in/Test.java", //
+            "class Test {",
+            "  String f() {",
+            "    var sb = new StringBuffer();",
+            "    return sb.append(42).toString();",
+            "  }",
+            "}")
+        .addOutputLines(
+            "out/Test.java", //
+            "class Test {",
+            "  String f() {",
+            "    var sb = new StringBuilder();",
+            "    return sb.append(42).toString();",
+            "  }",
+            "}")
+        .doTest();
+  }
+
   /** A test input. */
   public interface Lib {
     Enumeration<Integer> foos();