diff --git a/android/guava/pom.xml b/android/guava/pom.xml
index e01a6104fc9a..5deda6e057fc 100644
--- a/android/guava/pom.xml
+++ b/android/guava/pom.xml
@@ -90,6 +90,42 @@
maven-compiler-plugin
+
+
+
+ default-compile
+ compile
+
+ compile
+
+
+
+ **/Java8Usage.java
+
+
+
+ 8
+
+
+
+ main-compile
+ compile
+
+ compile
+
+
+
+ **/Java8Usage.java
+
+
+
+ maven-source-plugin
diff --git a/android/guava/src/com/google/common/base/Java8Usage.java b/android/guava/src/com/google/common/base/Java8Usage.java
new file mode 100644
index 000000000000..78130cf676d9
--- /dev/null
+++ b/android/guava/src/com/google/common/base/Java8Usage.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2020 The Guava 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.common.base;
+
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+
+/**
+ * A class that uses a couple Java 8 features but doesn't really do anything. This lets us attempt
+ * to load it and log a warning if that fails, giving users advance notice of our dropping Java 8
+ * support.
+ */
+/*
+ * This class should be annotated @GwtCompatible. But if we annotate it @GwtCompatible, then we need
+ * to build GwtCompatible.java (-source 7 -target 7 in the Android flavor) before we build
+ * Java8Usage.java (-source 8 target 8, which we already need to build before the rest of
+ * common.base). We could configure Maven to do that, but it's easier to just skip the annotation.
+ */
+final class Java8Usage {
+ @java.lang.annotation.Target(java.lang.annotation.ElementType.TYPE_USE)
+ @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
+ private @interface SomeTypeAnnotation {}
+
+ @CanIgnoreReturnValue
+ static @SomeTypeAnnotation String performCheck() {
+ Runnable r = () -> {};
+ r.run();
+ return "";
+ }
+
+ private Java8Usage() {}
+}
diff --git a/android/guava/src/com/google/common/base/MoreObjects.java b/android/guava/src/com/google/common/base/MoreObjects.java
index a56b2a69def0..a8ee412c67e0 100644
--- a/android/guava/src/com/google/common/base/MoreObjects.java
+++ b/android/guava/src/com/google/common/base/MoreObjects.java
@@ -15,10 +15,13 @@
package com.google.common.base;
import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.logging.Level.WARNING;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.concurrent.GuardedBy;
import java.util.Arrays;
+import java.util.logging.Logger;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;
/**
@@ -141,6 +144,38 @@ public static ToStringHelper toStringHelper(String className) {
* @since 18.0 (since 2.0 as {@code Objects.ToStringHelper}).
*/
public static final class ToStringHelper {
+ @GuardedBy("ToStringHelper.class")
+ private static boolean performedJava8CompatibilityCheck;
+
+ private static void java8CompatibilityCheck() {
+ @SuppressWarnings("GuardedBy")
+ boolean racyReadForDoubleCheckedLock = performedJava8CompatibilityCheck;
+ if (racyReadForDoubleCheckedLock) {
+ return;
+ }
+ synchronized (ToStringHelper.class) {
+ if (performedJava8CompatibilityCheck) {
+ return;
+ }
+ performedJava8CompatibilityCheck = true;
+ }
+
+ try {
+ Java8Usage.performCheck();
+ } catch (Throwable underlying) {
+ Exception toLog =
+ new Exception(
+ "Guava will drop support for Java 7 in 2021. Please let us know if this will cause"
+ + " you problems: https://github.com/google/guava/issues/5269",
+ underlying);
+ Logger.getLogger(ToStringHelper.class.getName())
+ .log(
+ WARNING,
+ "Java 7 compatibility warning: See https://github.com/google/guava/issues/5269",
+ toLog);
+ }
+ }
+
private final String className;
private final ValueHolder holderHead = new ValueHolder();
private ValueHolder holderTail = holderHead;
@@ -148,6 +183,7 @@ public static final class ToStringHelper {
/** Use {@link MoreObjects#toStringHelper(Object)} to create an instance. */
private ToStringHelper(String className) {
+ java8CompatibilityCheck();
this.className = checkNotNull(className);
}
diff --git a/android/pom.xml b/android/pom.xml
index f1b9fb1e1e5f..c1948fa53724 100644
--- a/android/pom.xml
+++ b/android/pom.xml
@@ -118,6 +118,16 @@
1.7
+
+
+ -sourcepath
+ doesnotexist
+
diff --git a/guava/pom.xml b/guava/pom.xml
index 4a7cd5c186d1..d95559cbcb48 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -90,6 +90,42 @@
maven-compiler-plugin
+
+
+
+ default-compile
+ compile
+
+ compile
+
+
+
+ **/Java8Usage.java
+
+
+
+ 8
+
+
+
+ main-compile
+ compile
+
+ compile
+
+
+
+ **/Java8Usage.java
+
+
+
+ maven-source-plugin
diff --git a/guava/src/com/google/common/base/Java8Usage.java b/guava/src/com/google/common/base/Java8Usage.java
new file mode 100644
index 000000000000..78130cf676d9
--- /dev/null
+++ b/guava/src/com/google/common/base/Java8Usage.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2020 The Guava 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.common.base;
+
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+
+/**
+ * A class that uses a couple Java 8 features but doesn't really do anything. This lets us attempt
+ * to load it and log a warning if that fails, giving users advance notice of our dropping Java 8
+ * support.
+ */
+/*
+ * This class should be annotated @GwtCompatible. But if we annotate it @GwtCompatible, then we need
+ * to build GwtCompatible.java (-source 7 -target 7 in the Android flavor) before we build
+ * Java8Usage.java (-source 8 target 8, which we already need to build before the rest of
+ * common.base). We could configure Maven to do that, but it's easier to just skip the annotation.
+ */
+final class Java8Usage {
+ @java.lang.annotation.Target(java.lang.annotation.ElementType.TYPE_USE)
+ @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
+ private @interface SomeTypeAnnotation {}
+
+ @CanIgnoreReturnValue
+ static @SomeTypeAnnotation String performCheck() {
+ Runnable r = () -> {};
+ r.run();
+ return "";
+ }
+
+ private Java8Usage() {}
+}
diff --git a/guava/src/com/google/common/base/MoreObjects.java b/guava/src/com/google/common/base/MoreObjects.java
index cf901b5954e0..a182829660f2 100644
--- a/guava/src/com/google/common/base/MoreObjects.java
+++ b/guava/src/com/google/common/base/MoreObjects.java
@@ -15,10 +15,13 @@
package com.google.common.base;
import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.logging.Level.WARNING;
import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.concurrent.GuardedBy;
import java.util.Arrays;
+import java.util.logging.Logger;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
@@ -141,6 +144,38 @@ public static ToStringHelper toStringHelper(String className) {
* @since 18.0 (since 2.0 as {@code Objects.ToStringHelper}).
*/
public static final class ToStringHelper {
+ @GuardedBy("ToStringHelper.class")
+ private static boolean performedJava8CompatibilityCheck;
+
+ private static void java8CompatibilityCheck() {
+ @SuppressWarnings("GuardedBy")
+ boolean racyReadForDoubleCheckedLock = performedJava8CompatibilityCheck;
+ if (racyReadForDoubleCheckedLock) {
+ return;
+ }
+ synchronized (ToStringHelper.class) {
+ if (performedJava8CompatibilityCheck) {
+ return;
+ }
+ performedJava8CompatibilityCheck = true;
+ }
+
+ try {
+ Java8Usage.performCheck();
+ } catch (Throwable underlying) {
+ Exception toLog =
+ new Exception(
+ "Guava will drop support for Java 7 in 2021. Please let us know if this will cause"
+ + " you problems: https://github.com/google/guava/issues/5269",
+ underlying);
+ Logger.getLogger(ToStringHelper.class.getName())
+ .log(
+ WARNING,
+ "Java 7 compatibility warning: See https://github.com/google/guava/issues/5269",
+ toLog);
+ }
+ }
+
private final String className;
private final ValueHolder holderHead = new ValueHolder();
private ValueHolder holderTail = holderHead;
@@ -148,6 +183,7 @@ public static final class ToStringHelper {
/** Use {@link MoreObjects#toStringHelper(Object)} to create an instance. */
private ToStringHelper(String className) {
+ java8CompatibilityCheck();
this.className = checkNotNull(className);
}
diff --git a/pom.xml b/pom.xml
index 01ee0f43c76f..22d68ffdf448 100644
--- a/pom.xml
+++ b/pom.xml
@@ -119,6 +119,16 @@
1.8
+
+
+ -sourcepath
+ doesnotexist
+