Restrict span annotations to methods

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### ⚠️ Breaking changes
 
+- `@WithSpan` and `@AddingSpanAttributes` no longer allow targeting constructors
+  (which didn't work properly anyways).
 - Kotlin suspend function `@WithSpan` instrumentation now uses only the
   `kotlinx-coroutines-annotations` selector and is disabled by default. Use
   `otel.instrumentation.kotlinx-coroutines-annotations.enabled=true` instead of the

docs/apidiffs/current_vs_latest/opentelemetry-instrumentation-annotations.txt

@@ -1,2 +1,9 @@
 Comparing source compatibility of opentelemetry-instrumentation-annotations-3.0.0-SNAPSHOT.jar against opentelemetry-instrumentation-annotations-2.32.0.jar
-No changes.
+===  UNCHANGED ANNOTATION: PUBLIC ABSTRACT io.opentelemetry.instrumentation.annotations.AddingSpanAttributes  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	***  MODIFIED ANNOTATION: java.lang.annotation.Target
+		***  MODIFIED ELEMENT: value=java.lang.annotation.ElementType.METHOD (<- java.lang.annotation.ElementType.METHOD,java.lang.annotation.ElementType.CONSTRUCTOR)
+===  UNCHANGED ANNOTATION: PUBLIC ABSTRACT io.opentelemetry.instrumentation.annotations.WithSpan  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	***  MODIFIED ANNOTATION: java.lang.annotation.Target
+		***  MODIFIED ELEMENT: value=java.lang.annotation.ElementType.METHOD (<- java.lang.annotation.ElementType.METHOD,java.lang.annotation.ElementType.CONSTRUCTOR)

instrumentation-annotations/src/main/java/io/opentelemetry/instrumentation/annotations/AddingSpanAttributes.java

@@ -14,9 +14,7 @@
  * This annotation marks that an execution of this method is able to add attributes to the current
  * span {@link io.opentelemetry.api.trace.Span}.
  *
- * <p>Using this annotation on constructors is not supported by OpenTelemetry instrumentation. The
- * {@link ElementType#CONSTRUCTOR} target exists only for backward compatibility and is planned to
- * be removed in the 3.0 release.
+ * <p>This annotation can only be applied to methods. Constructor instrumentation is not supported.
  *
  * <p>Application developers can use this annotation to signal OpenTelemetry auto-instrumentation
  * that attributes annotated with the {@link
@@ -34,6 +32,6 @@
  * <p>If you are a library developer, then probably you should NOT use this annotation, because it
  * is non-functional without some form of auto-instrumentation.
  */
-@Target({ElementType.METHOD, ElementType.CONSTRUCTOR}) // CONSTRUCTOR target to be removed in 3.0
+@Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface AddingSpanAttributes {}

instrumentation-annotations/src/main/java/io/opentelemetry/instrumentation/annotations/WithSpan.java

@@ -16,17 +16,15 @@
  * This annotation marks that an execution of this method should result in a new {@link
  * io.opentelemetry.api.trace.Span}.
  *
- * <p>Using this annotation on constructors is not supported by OpenTelemetry instrumentation. The
- * {@link ElementType#CONSTRUCTOR} target exists only for backward compatibility and is planned to
- * be removed in the 3.0 release.
+ * <p>This annotation can only be applied to methods. Constructor instrumentation is not supported.
  *
  * <p>Application developers can use this annotation to signal OpenTelemetry auto-instrumentation
  * that a new span should be created whenever the marked method is executed.
  *
  * <p>If you are a library developer, then probably you should NOT use this annotation, because it
  * is non-functional without some form of auto-instrumentation.
  */
-@Target({ElementType.METHOD, ElementType.CONSTRUCTOR}) // CONSTRUCTOR target to be removed in 3.0
+@Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface WithSpan {
   /**

instrumentation/opentelemetry-instrumentation-annotations-1.16/javaagent/src/test/java/io/opentelemetry/test/annotation/AddingSpanAttributesInstrumentationTest.java

@@ -12,7 +12,10 @@
 
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.instrumentation.annotations.AddingSpanAttributes;
 import io.opentelemetry.instrumentation.testing.junit.AgentInstrumentationExtension;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
@@ -77,37 +80,9 @@ void noExistingSpan() {
   }
 
   @Test
-  void constructorOnlyAddingSpanAttributesDoesNotTransformType() {
-    testing.runWithSpan(
-        "root", () -> new ConstructorOnlyAddingSpanAttributes("foo", "bar", null, "baz"));
-
-    testing.waitAndAssertTraces(
-        trace ->
-            trace.hasSpansSatisfyingExactly(
-                span ->
-                    span.hasName("root")
-                        .hasKind(SpanKind.INTERNAL)
-                        .hasNoParent()
-                        .hasTotalAttributeCount(0)));
-  }
-
-  @Test
-  void constructorAndMethodAddingSpanAttributesIgnoresConstructor() {
-    testing.runWithSpan(
-        "root",
-        () ->
-            new ConstructedWithAddingSpanAttributes("foo", "bar", null, "baz")
-                .addAttributes("method"));
-
-    testing.waitAndAssertTraces(
-        trace ->
-            trace.hasSpansSatisfyingExactly(
-                span ->
-                    span.hasName("root")
-                        .hasKind(SpanKind.INTERNAL)
-                        .hasNoParent()
-                        .hasAttributesSatisfyingExactly(
-                            equalTo(stringKey("methodAttribute"), "method"))));
+  void annotationTargetsMethodsOnly() {
+    assertThat(AddingSpanAttributes.class.getAnnotation(Target.class).value())
+        .containsExactly(ElementType.METHOD);
   }
 
   @Test

instrumentation/opentelemetry-instrumentation-annotations-1.16/javaagent/src/test/java/io/opentelemetry/test/annotation/TracedWithSpan.java

@@ -15,10 +15,6 @@ class TracedWithSpan {
 
   TracedWithSpan() {}
 
-  // used to verify that constructor with @WithSpan annotation doesn't break instrumentation
-  @WithSpan
-  TracedWithSpan(String unused) {}
-
   @WithSpan
   String otel() {
     return "hello!";

instrumentation/opentelemetry-instrumentation-annotations-1.16/javaagent/src/test/java/io/opentelemetry/test/annotation/WithSpanInstrumentationTest.java

@@ -19,6 +19,8 @@
 import io.opentelemetry.instrumentation.annotations.WithSpan;
 import io.opentelemetry.instrumentation.testing.junit.AgentInstrumentationExtension;
 import io.opentelemetry.sdk.trace.data.StatusData;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
 import java.lang.reflect.Modifier;
 import java.util.concurrent.CompletableFuture;
 import net.bytebuddy.ByteBuddy;
@@ -146,11 +148,9 @@ void excludedMethod() throws InterruptedException {
   }
 
   @Test
-  void annotatedConstructorDoesNotCreateSpan() throws InterruptedException {
-    new TracedWithSpan("unused");
-
-    Thread.sleep(500); // sleep a bit just to make sure no span is captured
-    assertThat(testing.waitForTraces(0)).isEmpty();
+  void annotationTargetsMethodsOnly() {
+    assertThat(WithSpan.class.getAnnotation(Target.class).value())
+        .containsExactly(ElementType.METHOD);
   }
 
   @Test