Handle unqualified instance method names in refaster

Previously unqualified methods names were being handled using logic intended for local variables, which failed to match them.

Unqualified instance method names are relatively rare in templates. The motivating example was a template intended to match on an anonymous class creation, where code in the class called a method from a superclass by its simple name.

PiperOrigin-RevId: 621197168

core/src/main/java/com/google/errorprone/refaster/UMethodIdent.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2024 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.refaster;
+
+import static com.google.errorprone.refaster.Unifier.unifications;
+
+import com.google.auto.value.AutoValue;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+import com.sun.tools.javac.code.Symbol.ClassSymbol;
+import com.sun.tools.javac.tree.JCTree.JCExpression;
+
+/** Identifier representing an unqualified instant method. */
+@AutoValue
+public abstract class UMethodIdent extends UIdent {
+  public static UMethodIdent create(UClassIdent classIdent, CharSequence member, UType memberType) {
+    return new AutoValue_UMethodIdent(classIdent, StringName.of(member), memberType);
+  }
+
+  public static UMethodIdent create(ClassSymbol classSym, CharSequence member, UType memberType) {
+    return create(UClassIdent.create(classSym), member, memberType);
+  }
+
+  abstract UClassIdent classIdent();
+
+  @Override
+  public abstract StringName getName();
+
+  abstract UType memberType();
+
+  @Override
+  public JCExpression inline(Inliner inliner) throws CouldNotResolveImportException {
+    return inliner.maker().Ident(getName().inline(inliner));
+  }
+
+  @Override
+  protected Choice<Unifier> defaultAction(Tree node, Unifier unifier) {
+    Symbol symbol = ASTHelpers.getSymbol(node);
+    if (symbol != null) {
+      return classIdent()
+          .unify(symbol.getEnclosingElement(), unifier)
+          .thenChoose(unifications(getName(), symbol.getSimpleName()))
+          .thenChoose(unifications(memberType(), symbol.asType()));
+    }
+    return Choice.none();
+  }
+}

core/src/main/java/com/google/errorprone/refaster/UTemplater.java

@@ -354,6 +354,13 @@ private UStaticIdent staticMember(Symbol symbol) {
         template(symbol.asType()));
   }
 
+  private UMethodIdent method(Symbol symbol) {
+    return UMethodIdent.create(
+        (ClassSymbol) symbol.getEnclosingElement(),
+        symbol.getSimpleName(),
+        template(symbol.asType()));
+  }
+
   private static final UStaticIdent ANY_OF;
   private static final UStaticIdent IS_INSTANCE;
   private static final UStaticIdent CLAZZ;
@@ -622,6 +629,8 @@ public UExpression visitIdentifier(IdentifierTree tree, Void v) {
     switch (sym.getKind()) {
       case TYPE_PARAMETER:
         return UTypeVarIdent.create(tree.getName());
+      case METHOD:
+        return method(sym);
       default:
         return ULocalVarIdent.create(tree.getName());
     }

core/src/test/java/com/google/errorprone/refaster/TemplateIntegrationTest.java

@@ -379,4 +379,9 @@ public void typeArgumentsMethodInvocation() throws IOException {
   public void memberSelectAndMethodParameterDisambiguation() throws IOException {
     runTest("MemberSelectAndMethodParameterDisambiguationTemplate");
   }
+
+  @Test
+  public void unqualifiedMethod() throws IOException {
+    runTest("UnqualifiedMethodTemplate");
+  }
 }

core/src/test/java/com/google/errorprone/refaster/testdata/input/UnqualifiedMethodTemplateExample.java

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2024 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.refaster.testdata;
+
+/** Test data for {@code UnqualifiedMethodTemplate}. */
+public class UnqualifiedMethodTemplateExample {
+  public int example() {
+    return hashCode();
+  }
+}

core/src/test/java/com/google/errorprone/refaster/testdata/output/UnqualifiedMethodTemplateExample.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2024 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.refaster.testdata;
+
+import java.util.Objects;
+
+/** Test data for {@code UnqualifiedMethodTemplate}. */
+public class UnqualifiedMethodTemplateExample {
+  public int example() {
+    return Objects.hashCode(this);
+  }
+}

core/src/test/java/com/google/errorprone/refaster/testdata/template/UnqualifiedMethodTemplate.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2024 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.refaster.testdata.template;
+
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+import java.util.Objects;
+
+public class UnqualifiedMethodTemplate {
+  @BeforeTemplate
+  public int before() {
+    return hashCode();
+  }
+
+  @AfterTemplate
+  public int after() {
+    return Objects.hashCode(this);
+  }
+}