Cloned from CL 870815517 by 'g4 patch'.

core/src/main/java/com/google/errorprone/bugpatterns/RecordAccessorInCompactConstructor.java

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2026 The Error Prone Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.ERROR;
+
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.IdentifierTree;
+import com.sun.source.tree.LambdaExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import com.sun.source.tree.MethodTree;
+import com.sun.tools.javac.code.Flags;
+import com.sun.tools.javac.code.Symbol.ClassSymbol;
+import com.sun.tools.javac.code.Symbol.MethodSymbol;
+import com.sun.tools.javac.code.Symbol.RecordComponent;
+
+/**
+ * Detects when record accessors read uninitialized fields inside a compact constructor. Use the
+ * component parameter instead.
+ *
+ * <p>Example:
+ *
+ * {@snippet :
+ * record R(int x) {
+ *   public R {
+ *     int y = x(); // BUG: use `x` instead
+ *   }
+ * }
+ * }
+ */
+@BugPattern(
+    summary =
+        "Record accessors read uninitialized fields inside a compact constructor. Use the"
+            + " component parameter instead.",
+    severity = ERROR)
+public final class RecordAccessorInCompactConstructor extends BugChecker
+    implements MethodInvocationTreeMatcher {
+
+  @Override
+  public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+    MethodTree enclosingMethod = ASTHelpers.findEnclosingNode(state.getPath(), MethodTree.class);
+    if (enclosingMethod == null) {
+      return Description.NO_MATCH;
+    }
+
+    MethodSymbol methodSym = ASTHelpers.getSymbol(enclosingMethod);
+    if (methodSym == null || (methodSym.flags() & Flags.COMPACT_RECORD_CONSTRUCTOR) == 0) {
+      return Description.NO_MATCH;
+    }
+
+    if (state.findEnclosing(LambdaExpressionTree.class) != null) {
+      return Description.NO_MATCH;
+    }
+
+    MethodSymbol calledMethod = ASTHelpers.getSymbol(tree);
+    if (calledMethod == null) {
+      return Description.NO_MATCH;
+    }
+
+    ClassSymbol recordClass = methodSym.enclClass();
+    if (!calledMethod.owner.equals(recordClass)) {
+      return Description.NO_MATCH;
+    }
+
+    String componentName = null;
+    for (RecordComponent rc : recordClass.getRecordComponents()) {
+      if (calledMethod.equals(rc.accessor)) {
+        componentName = rc.name.toString();
+        break;
+      }
+    }
+
+    if (componentName == null) {
+      return Description.NO_MATCH;
+    }
+
+    ExpressionTree receiver = ASTHelpers.getReceiver(tree);
+    if (receiver != null
+        && !(receiver instanceof IdentifierTree identifierTree
+            && identifierTree.getName().contentEquals("this"))) {
+      return Description.NO_MATCH;
+    }
+
+    return buildDescription(tree)
+        .setMessage(
+            "Record accessors inside compact constructors read uninitialized fields (JLS"
+                + " §8.10.4.2). Use the parameter directly.")
+        .addFix(SuggestedFix.replace(tree, componentName))
+        .build();
+  }
+}

core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java

@@ -338,6 +338,7 @@
 import com.google.errorprone.bugpatterns.RandomCast;
 import com.google.errorprone.bugpatterns.RandomModInteger;
 import com.google.errorprone.bugpatterns.ReachabilityFenceUsage;
+import com.google.errorprone.bugpatterns.RecordAccessorInCompactConstructor;
 import com.google.errorprone.bugpatterns.RedundantControlFlow;
 import com.google.errorprone.bugpatterns.RedundantOverride;
 import com.google.errorprone.bugpatterns.RedundantSetterCall;
@@ -851,6 +852,7 @@ public static ScannerSupplier warningChecks() {
           ProvidesNull.class,
           RandomCast.class,
           RandomModInteger.class,
+          RecordAccessorInCompactConstructor.class,
           RectIntersectReturnValueIgnored.class,
           RedundantSetterCall.class,
           RequiredModifiersChecker.class,