From 09d870e26be80c4d4cf790a2e937727d83b5c239 Mon Sep 17 00:00:00 2001
From: Gonzalo Amestoy <amestoyg@gmail.com>
Date: Mon, 5 Dec 2022 23:43:19 +0100
Subject: [PATCH 1/2] Introduce CollectionForEach Refaster rule

---
 .../errorprone/refasterrules/CollectionRules.java  | 14 ++++++++++++++
 .../refasterrules/CollectionRulesTestInput.java    |  4 ++++
 .../refasterrules/CollectionRulesTestOutput.java   |  4 ++++
 3 files changed, 22 insertions(+)

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
index 19df9107db..796da37d5a 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
@@ -17,6 +17,7 @@
 import java.util.Queue;
 import java.util.Set;
 import java.util.SortedSet;
+import java.util.function.Consumer;
 import java.util.function.IntFunction;
 import java.util.stream.Stream;
 import tech.picnic.errorprone.refaster.annotation.OnlineDocumentation;
@@ -404,6 +405,19 @@ Optional<T> after(Queue<T> queue) {
     }
   }
 
+  /** Prefer calling {@link Collection#forEach} ()} over more contrived alternatives. */
+  static final class CollectionForEach<T> {
+    @BeforeTemplate
+    void before(Collection<T> collection, Consumer<T> consumer) {
+      collection.stream().forEach(consumer);
+    }
+
+    @AfterTemplate
+    void after(Collection<T> collection, Consumer<T> consumer) {
+      collection.forEach(consumer);
+    }
+  }
+
   // XXX: collection.stream().noneMatch(e -> e.equals(other))
   // ^ This is !collection.contains(other). Do we already rewrite variations on this?
 }
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java
index c5c3f686d5..68f6f79bfb 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestInput.java
@@ -186,4 +186,8 @@ ImmutableSet<Optional<String>> testRemoveOptionalFirstQueueElement() {
             ? Optional.ofNullable(new LinkedList<String>().remove())
             : Optional.empty());
   }
+
+  void testCollectionForEach() {
+    ImmutableSet.of(1).stream().forEach(String::valueOf);
+  }
 }
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java
index 7d580729cc..0ebaa40f3b 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/CollectionRulesTestOutput.java
@@ -136,4 +136,8 @@ ImmutableSet<Optional<String>> testRemoveOptionalFirstQueueElement() {
         Optional.ofNullable(new LinkedList<String>().poll()),
         Optional.ofNullable(new LinkedList<String>().poll()));
   }
+
+  void testCollectionForEach() {
+    ImmutableSet.of(1).forEach(String::valueOf);
+  }
 }

From 67b4b9a7990e9f02baa8a85b934ba43f1d502078 Mon Sep 17 00:00:00 2001
From: Gonzalo Amestoy <amestoyg@gmail.com>
Date: Tue, 6 Dec 2022 08:24:34 +0100
Subject: [PATCH 2/2] Define a more generic rule for Consumer

---
 .../picnic/errorprone/refasterrules/CollectionRules.java    | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
index 796da37d5a..90dc4f183f 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/CollectionRules.java
@@ -405,15 +405,15 @@ Optional<T> after(Queue<T> queue) {
     }
   }
 
-  /** Prefer calling {@link Collection#forEach} ()} over more contrived alternatives. */
+  /** Prefer {@link Collection#forEach(Consumer)} over more contrived alternatives. */
   static final class CollectionForEach<T> {
     @BeforeTemplate
-    void before(Collection<T> collection, Consumer<T> consumer) {
+    void before(Collection<T> collection, Consumer<? super T> consumer) {
       collection.stream().forEach(consumer);
     }
 
     @AfterTemplate
-    void after(Collection<T> collection, Consumer<T> consumer) {
+    void after(Collection<T> collection, Consumer<? super T> consumer) {
       collection.forEach(consumer);
     }
   }