Add logic to AutoValue to detect the confusing case where you think you are using JavaBeans conventions (like getFoo()) but you aren't because at least one method isn't. Then a Builder setter like setFoo will be rejected because it would have had to be called setGetFoo. This change detects that this might have happened and shows a list of the methods that prevented the JavaBeans conventions from being applied.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=119569372

5 files changed, 81 insertions, 10 deletions

diff --git a/value/pom.xml b/value/pom.xml
index 52ae4642..cf8e5424 100644
--- a/value/pom.xml
+++ b/value/pom.xml
@@ -79,7 +79,7 @@
     <dependency>
       <groupId>com.google.testing.compile</groupId>
       <artifactId>compile-testing</artifactId>
-      <version>0.6</version>
+      <version>0.9</version>
       <scope>test</scope>
     </dependency>
     <dependency>
diff --git a/value/src/main/java/com/google/auto/value/processor/AutoValueProcessor.java b/value/src/main/java/com/google/auto/value/processor/AutoValueProcessor.java
index b527b739..d2bf1fa5 100644
--- a/value/src/main/java/com/google/auto/value/processor/AutoValueProcessor.java
+++ b/value/src/main/java/com/google/auto/value/processor/AutoValueProcessor.java
@@ -517,12 +517,12 @@ public class AutoValueProcessor extends AbstractProcessor {
   }
 
   private ImmutableBiMap<String, ExecutableElement> propertyNameToMethodMap(
-      Iterable<ExecutableElement> propertyMethods) {
+      Set<ExecutableElement> propertyMethods) {
     Map<String, ExecutableElement> map = Maps.newLinkedHashMap();
-    boolean allGetters = allGetters(propertyMethods);
+    boolean allPrefixed = gettersAllPrefixed(propertyMethods);
     for (ExecutableElement method : propertyMethods) {
       String methodName = method.getSimpleName().toString();
-      String name = allGetters ? nameWithoutPrefix(methodName) : methodName;
+      String name = allPrefixed ? nameWithoutPrefix(methodName) : methodName;
       Object old = map.put(name, method);
       if (old != null) {
         errorReporter.reportError("More than one @AutoValue property called " + name, method);
@@ -531,18 +531,23 @@ public class AutoValueProcessor extends AbstractProcessor {
     return ImmutableBiMap.copyOf(map);
   }
 
-  private static boolean allGetters(Iterable<ExecutableElement> methods) {
+  private static boolean gettersAllPrefixed(Set<ExecutableElement> methods) {
+    return prefixedGettersIn(methods).size() == methods.size();
+  }
+
+  static ImmutableSet<ExecutableElement> prefixedGettersIn(Iterable<ExecutableElement> methods) {
+    ImmutableSet.Builder<ExecutableElement> getters = ImmutableSet.builder();
     for (ExecutableElement method : methods) {
       String name = method.getSimpleName().toString();
       // TODO(emcmanus): decide whether getfoo() (without a capital) is a getter. Currently it is.
       boolean get = name.startsWith("get") && !name.equals("get");
       boolean is = name.startsWith("is") && !name.equals("is")
           && method.getReturnType().getKind() == TypeKind.BOOLEAN;
-      if (!get && !is) {
-        return false;
+      if (get || is) {
+        getters.add(method);
       }
     }
-    return true;
+    return getters.build();
   }
 
   private Set<TypeMirror> allMethodAnnotationTypes(Iterable<ExecutableElement> methods) {
diff --git a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
index 866632fd..56148565 100644
--- a/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
+++ b/value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java
@@ -212,8 +212,11 @@ class BuilderMethodClassifier {
 
   /**
    * Classifies a method given that it has no arguments. Currently a method with no
-   * arguments can only be a {@code build()} method, meaning that its return type must be the
-   * {@code @AutoValue} class.
+   * arguments can be a {@code build()} method, meaning that its return type must be the
+   * {@code @AutoValue} class; it can be a getter, with the same signature as one of
+   * the property getters in the {@code @AutoValue} class; or it can be a property builder,
+   * like {@code ImmutableList.Builder<String> foosBuilder()} for the property defined by
+   * {@code ImmutableList<String> foos()} or {@code getFoos()}.
    *
    * @return true if the method was successfully classified, false if an error has been reported.
    */
@@ -328,6 +331,7 @@ class BuilderMethodClassifier {
       // propertyNameToSetters can't be null when we call put on it below.
       errorReporter.reportError(
           "Method does not correspond to a property of " + autoValueClass, method);
+      checkForFailedJavaBean(method);
       return false;
     }
     if (!checkSetterParameter(valueGetter, method)) {
@@ -342,6 +346,25 @@ class BuilderMethodClassifier {
     }
   }
 
+  // A frequence source of problems is where the JavaBeans conventions have been followed for
+  // most but not all getters. Then AutoValue considers that they haven't been followed at all,
+  // so you might have a property called getFoo where you thought it was called just foo, and
+  // you might not understand why your setter called setFoo is rejected (it would have to be called
+  // setGetFoo).
+  private void checkForFailedJavaBean(ExecutableElement rejectedSetter) {
+    ImmutableSet<ExecutableElement> allGetters = getterToPropertyName.keySet();
+    ImmutableSet<ExecutableElement> prefixedGetters =
+        AutoValueProcessor.prefixedGettersIn(allGetters);
+    if (prefixedGetters.size() < allGetters.size()
+        && prefixedGetters.size() >= allGetters.size() / 2) {
+      String note =
+          "This might be because you are using the getFoo() convention"
+              + " for some but not all methods. These methods don't follow the convention: "
+              + Sets.difference(allGetters, prefixedGetters);
+      errorReporter.reportNote(note, rejectedSetter);
+    }
+  }
+
   /**
    * Checks that the given setter method has a parameter type that is compatible with the return
    * type of the given getter. Compatible means either that it is the same, or that it is a type
diff --git a/value/src/main/java/com/google/auto/value/processor/ErrorReporter.java b/value/src/main/java/com/google/auto/value/processor/ErrorReporter.java
index 6e519213..23f7e5ce 100644
--- a/value/src/main/java/com/google/auto/value/processor/ErrorReporter.java
+++ b/value/src/main/java/com/google/auto/value/processor/ErrorReporter.java
@@ -36,6 +36,16 @@ class ErrorReporter {
   }
 
   /**
+   * Issue a compilation note.
+   *
+   * @param msg the text of the note
+   * @param e the element to which it pertains
+   */
+  void reportNote(String msg, Element e) {
+    messager.printMessage(Diagnostic.Kind.NOTE, msg, e);
+  }
+
+  /**
    * Issue a compilation warning.
    *
    * @param msg the text of the warning
diff --git a/value/src/test/java/com/google/auto/value/processor/CompilationTest.java b/value/src/test/java/com/google/auto/value/processor/CompilationTest.java
index ea9f37c9..0b38f10a 100644
--- a/value/src/test/java/com/google/auto/value/processor/CompilationTest.java
+++ b/value/src/test/java/com/google/auto/value/processor/CompilationTest.java
@@ -1131,6 +1131,39 @@ public class CompilationTest {
         .in(javaFileObject).onLine(12);
   }
 
+  // Check that we get a helpful error message if some of your properties look like getters but
+  // others don't.
+  @Test
+  public void autoValueBuilderBeansConfusion() {
+    JavaFileObject javaFileObject = JavaFileObjects.forSourceLines(
+        "foo.bar.Item",
+        "package foo.bar;",
+        "",
+        "import com.google.auto.value.AutoValue;",
+        "",
+        "@AutoValue",
+        "public abstract class Item {",
+        "  abstract String getTitle();",
+        "  abstract boolean hasThumbnail();",
+        "",
+        "  @AutoValue.Builder",
+        "  public interface Builder {",
+        "    Builder setTitle(String title);",
+        "    Builder setHasThumbnail(boolean t);",
+        "    Item build();",
+        "  }",
+        "}");
+    assertAbout(javaSource())
+        .that(javaFileObject)
+        .processedWith(new AutoValueProcessor(), new AutoValueBuilderProcessor())
+        .failsToCompile()
+        .withErrorContaining("Method does not correspond to a property of foo.bar.Item")
+        .in(javaFileObject).onLine(12)
+        .and()
+        .withNoteContaining("hasThumbnail")
+        .in(javaFileObject).onLine(12);
+  }
+
   @Test
   public void autoValueBuilderExtraSetter() {
     JavaFileObject javaFileObject = JavaFileObjects.forSourceLines(