Improve generate constructor parameter names in the `@Memoized` extension.

Previously we just added `$` to each name, in case one of them might be a Java keyword. This turns out to cause an issue with Error Prone's `/* foo= */` checked parameter-name comments, because people end up having to write `/* foo$= */` for the check to pass. With the approach here, you'll only have to write a funny parameter name if your property name is a keyword.

RELNOTES=The constructor parameter names in the class generated by `@Memoized` no longer add a `$`.
PiperOrigin-RevId: 521852747

2 files changed, 50 insertions, 4 deletions

diff --git a/value/src/main/java/com/google/auto/value/extension/memoized/processor/MemoizeExtension.java b/value/src/main/java/com/google/auto/value/extension/memoized/processor/MemoizeExtension.java
index 65a8c95c..b611ae1e 100644
--- a/value/src/main/java/com/google/auto/value/extension/memoized/processor/MemoizeExtension.java
+++ b/value/src/main/java/com/google/auto/value/extension/memoized/processor/MemoizeExtension.java
@@ -17,6 +17,7 @@ package com.google.auto.value.extension.memoized.processor;
 
 import static com.google.auto.common.GeneratedAnnotationSpecs.generatedAnnotationSpec;
 import static com.google.auto.common.MoreStreams.toImmutableList;
+import static com.google.auto.common.MoreStreams.toImmutableMap;
 import static com.google.auto.common.MoreStreams.toImmutableSet;
 import static com.google.auto.value.extension.memoized.processor.ClassNames.MEMOIZED_NAME;
 import static com.google.auto.value.extension.memoized.processor.MemoizedValidator.getAnnotationMirror;
@@ -44,6 +45,7 @@ import com.google.auto.common.MoreElements;
 import com.google.auto.service.AutoService;
 import com.google.auto.value.extension.AutoValueExtension;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.annotations.FormatMethod;
 import com.squareup.javapoet.AnnotationSpec;
@@ -58,6 +60,7 @@ import com.squareup.javapoet.TypeSpec;
 import com.squareup.javapoet.TypeVariableName;
 import java.util.List;
 import java.util.Optional;
+import java.util.Set;
 import javax.annotation.processing.Messager;
 import javax.annotation.processing.ProcessingEnvironment;
 import javax.lang.model.SourceVersion;
@@ -193,15 +196,36 @@ public final class MemoizeExtension extends AutoValueExtension {
 
     private MethodSpec constructor() {
       MethodSpec.Builder constructor = constructorBuilder();
+      // TODO(b/35944623): Replace this with a standard way of avoiding keywords.
+      Set<String> propertyNames = context.properties().keySet();
+      ImmutableMap<String, String> parameterNames =
+          propertyNames.stream()
+              .collect(
+                  toImmutableMap(name -> name, name -> generateIdentifier(name, propertyNames)));
       context
           .propertyTypes()
-          .forEach((name, type) -> constructor.addParameter(annotatedType(type), name + "$"));
+          .forEach(
+              (name, type) ->
+                  constructor.addParameter(annotatedType(type), parameterNames.get(name)));
       String superParams =
-          context.properties().keySet().stream().map(n -> n + "$").collect(joining(", "));
+          context.properties().keySet().stream().map(parameterNames::get).collect(joining(", "));
       constructor.addStatement("super($L)", superParams);
       return constructor.build();
     }
 
+    private static String generateIdentifier(String name, Set<String> existingNames) {
+      if (!SourceVersion.isKeyword(name)) {
+        return name;
+      }
+      for (int i = 0;; i++) {
+        String newName = name + i;
+        if (!existingNames.contains(newName)) {
+          return newName;
+        }
+      }
+    }
+
+
 
     private boolean isHashCodeMemoized() {
       return memoizedMethods(context).stream()
diff --git a/value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ExtensionClassTypeSpecBuilder.java b/value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ExtensionClassTypeSpecBuilder.java
index e7578911..a8bcef53 100644
--- a/value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ExtensionClassTypeSpecBuilder.java
+++ b/value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ExtensionClassTypeSpecBuilder.java
@@ -18,6 +18,7 @@ package com.google.auto.value.extension.toprettystring.processor;
 
 import static com.google.auto.common.GeneratedAnnotationSpecs.generatedAnnotationSpec;
 import static com.google.auto.common.MoreStreams.toImmutableList;
+import static com.google.auto.common.MoreStreams.toImmutableMap;
 import static com.squareup.javapoet.MethodSpec.constructorBuilder;
 import static com.squareup.javapoet.TypeSpec.classBuilder;
 import static java.util.stream.Collectors.joining;
@@ -28,6 +29,7 @@ import static javax.lang.model.element.Modifier.FINAL;
 import com.google.auto.value.extension.AutoValueExtension;
 import com.google.auto.value.extension.AutoValueExtension.Context;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.MethodSpec;
@@ -36,6 +38,7 @@ import com.squareup.javapoet.TypeName;
 import com.squareup.javapoet.TypeSpec;
 import com.squareup.javapoet.TypeVariableName;
 import java.util.List;
+import java.util.Set;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.Elements;
@@ -117,15 +120,34 @@ final class ExtensionClassTypeSpecBuilder {
 
   private MethodSpec constructor() {
     MethodSpec.Builder constructor = constructorBuilder();
+    // TODO(b/35944623): Replace this with a standard way of avoiding keywords.
+    Set<String> propertyNames = context.properties().keySet();
+    ImmutableMap<String, String> parameterNames =
+        propertyNames.stream()
+            .collect(toImmutableMap(name -> name, name -> generateIdentifier(name, propertyNames)));
     context
         .propertyTypes()
-        .forEach((name, type) -> constructor.addParameter(annotatedType(type), name + "$"));
+        .forEach(
+            (name, type) ->
+                constructor.addParameter(annotatedType(type), parameterNames.get(name)));
     String superParams =
-        context.properties().keySet().stream().map(n -> n + "$").collect(joining(", "));
+        context.properties().keySet().stream().map(parameterNames::get).collect(joining(", "));
     constructor.addStatement("super($L)", superParams);
     return constructor.build();
   }
 
+  private static String generateIdentifier(String name, Set<String> existingNames) {
+    if (!SourceVersion.isKeyword(name)) {
+      return name;
+    }
+    for (int i = 0; ; i++) {
+      String newName = name + i;
+      if (!existingNames.contains(newName)) {
+        return newName;
+      }
+    }
+  }
+
   /** Translate a {@link TypeMirror} into a {@link TypeName}, including type annotations. */
   private static TypeName annotatedType(TypeMirror type) {
     List<AnnotationSpec> annotations =