Migrate the CollectionStreamForEach refactor to error-prone

README.md

@@ -185,6 +185,7 @@ Safe Logging can be found at [github.com/palantir/safe-logging](https://github.c
 - `ThrowSpecificity`: Prefer to declare more specific `throws` types than Exception and Throwable.
 - `UnsafeGaugeRegistration`: Use TaggedMetricRegistry.registerWithReplacement over TaggedMetricRegistry.gauge.
 - `BracesRequired`: Require braces for loops and if expressions.
+- `CollectionStreamForEach`: Collection.forEach is more efficient than Collection.stream().forEach.
 
 ### Programmatic Application
 

baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/CollectionStreamForEach.java

@@ -0,0 +1,82 @@
+/*
+ * (c) Copyright 2020 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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.palantir.baseline.errorprone;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.fixes.SuggestedFix;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.Matchers;
+import com.google.errorprone.matchers.method.MethodMatchers;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+import java.util.Collection;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+
+@AutoService(BugChecker.class)
+@BugPattern(
+        name = "CollectionStreamForEach",
+        link = "https://github.com/palantir/gradle-baseline#baseline-error-prone-checks",
+        linkType = BugPattern.LinkType.CUSTOM,
+        severity = BugPattern.SeverityLevel.WARNING,
+        summary = "Collection.forEach is more efficient than Collection.stream().forEach")
+public final class CollectionStreamForEach extends BugChecker implements BugChecker.MethodInvocationTreeMatcher {
+    private static final long serialVersionUID = 1L;
+
+    private static final Matcher<ExpressionTree> STREAM_FOR_EACH = MethodMatchers.instanceMethod()
+            .onDescendantOf(Stream.class.getName())
+            .namedAnyOf("forEach", "forEachOrdered")
+            .withParameters(Consumer.class.getName());
+
+    private static final Matcher<ExpressionTree> COLLECTION_STREAM = MethodMatchers.instanceMethod()
+            .onDescendantOf(Collection.class.getName())
+            .named("stream")
+            .withParameters();
+
+    private static final Matcher<MethodInvocationTree> matcher = Matchers.allOf(
+            STREAM_FOR_EACH,
+            Matchers.receiverOfInvocation(COLLECTION_STREAM));
+
+    @Override
+    public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+        if (matcher.matches(tree, state)) {
+            ExpressionTree stream = ASTHelpers.getReceiver(tree);
+            if (stream == null) {
+                // Should be impossible.
+                return describeMatch(tree);
+            }
+            ExpressionTree collection = ASTHelpers.getReceiver(stream);
+            if (collection == null) {
+                // Should be impossible.
+                return describeMatch(tree);
+            }
+            return buildDescription(tree)
+                    .addFix(SuggestedFix.builder()
+                            // Replaces forEachOrdered with forEach
+                            .merge(MoreSuggestedFixes.renameInvocationRetainingTypeArguments(tree, "forEach", state))
+                            .replace(stream, state.getSourceForNode(collection))
+                            .build())
+                    .build();
+        }
+        return Description.NO_MATCH;
+    }
+}

baseline-refaster-rules/src/test/java/com/palantir/baseline/refaster/CollectionStreamForEachTest.java → baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/CollectionStreamForEachTest.java

@@ -1,5 +1,5 @@
 /*
- * (c) Copyright 2019 Palantir Technologies Inc. All rights reserved.
+ * (c) Copyright 2020 Palantir Technologies Inc. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,33 +14,40 @@
  * limitations under the License.
  */
 
-package com.palantir.baseline.refaster;
+package com.palantir.baseline.errorprone;
 
-import org.junit.Test;
-
-public class CollectionStreamForEachTest {
+import org.junit.jupiter.api.Test;
 
+class CollectionStreamForEachTest {
     @Test
     public void test() {
-        RefasterTestHelper
-                .forRefactoring(CollectionStreamForEach.class)
-                .withInputLines(
-                        "Test",
+        fix()
+                .addInputLines(
+                        "Test.java",
                         "import java.util.List;",
                         "public class Test {",
                         "  void f(List<String> in) {",
                         "    in.stream().forEach(System.out::println);",
                         "    in.stream().forEachOrdered(System.out::println);",
+                        "    in.stream().<String>forEach(System.out::println);",
+                        "    in.stream().<String>forEachOrdered(System.out::println);",
                         "  }",
                         "}")
-                .hasOutputLines(
+                .addOutputLines(
+                        "Test.java",
                         "import java.util.List;",
                         "public class Test {",
                         "  void f(List<String> in) {",
                         "    in.forEach(System.out::println);",
                         "    in.forEach(System.out::println);",
+                        "    in.<String>forEach(System.out::println);",
+                        "    in.<String>forEach(System.out::println);",
                         "  }",
-                        "}");
+                        "}")
+                .doTest();
     }
 
+    private RefactoringValidator fix() {
+        return RefactoringValidator.of(new CollectionStreamForEach(), getClass());
+    }
 }

changelog/@unreleased/pr-1139.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Migrate the CollectionStreamForEach refactor to error-prone
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/1139

gradle-baseline-java/src/main/groovy/com/palantir/baseline/extensions/BaselineErrorProneExtension.java

@@ -25,6 +25,7 @@ public class BaselineErrorProneExtension {
             // Baseline checks
             "BracesRequired",
             "CatchBlockLogException",
+            "CollectionStreamForEach",
             // TODO(ckozak): re-enable pending scala check
             //"CatchSpecificity",
             "ExecutorSubmitRunnableFutureIgnored",