From 3affd633ce2e798051defe2e09090b46c0a49098 Mon Sep 17 00:00:00 2001
From: Liam Miller-Cushon <cushon@google.com>
Date: Mon, 17 Jun 2024 16:05:35 -0700
Subject: [PATCH] Adjust indentation of line comments inside expression
 switches

For statement switches there's some ambiguity about whether a comment documents the previous or next case:

```
  case 1:
    // case 1 falls through to 2
  case 2:
    doSomething()
```

```
  // this is information about case 1
  case 1:
  // this is information about case 2
  case 2:
    doSomething()
```

For expression switches there is no fall through, so assume that a line comments before a case label always apply to the case label after it.

PiperOrigin-RevId: 644163145
---
 .../java/java17/Java17InputAstVisitor.java    |  6 ++--
 .../java/FormatterIntegrationTest.java        | 11 ++++++-
 .../java/testdata/SwitchComment.input         | 31 +++++++++++++++++++
 .../java/testdata/SwitchComment.output        | 31 +++++++++++++++++++
 4 files changed, 76 insertions(+), 3 deletions(-)
 create mode 100644 core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.input
 create mode 100644 core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.output

diff --git a/core/src/main/java/com/google/googlejavaformat/java/java17/Java17InputAstVisitor.java b/core/src/main/java/com/google/googlejavaformat/java/java17/Java17InputAstVisitor.java
index e502f49a1..486324fb7 100644
--- a/core/src/main/java/com/google/googlejavaformat/java/java17/Java17InputAstVisitor.java
+++ b/core/src/main/java/com/google/googlejavaformat/java/java17/Java17InputAstVisitor.java
@@ -19,6 +19,7 @@
 
 import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableList;
+import com.google.googlejavaformat.Indent;
 import com.google.googlejavaformat.OpsBuilder;
 import com.google.googlejavaformat.OpsBuilder.BlankLineWanted;
 import com.google.googlejavaformat.java.JavaInputAstVisitor;
@@ -232,10 +233,11 @@ public Void visitCase(CaseTree node, Void unused) {
                 && !node.getBody().getKind().equals(Tree.Kind.BLOCK)
             ? plusFour
             : ZERO);
+    Indent commentIndent = node.getCaseKind().equals(CaseTree.CaseKind.RULE) ? ZERO : plusTwo;
     if (isDefault) {
-      token("default", plusTwo);
+      token("default", commentIndent);
     } else {
-      token("case", plusTwo);
+      token("case", commentIndent);
       builder.open(labels.size() > 1 ? plusFour : ZERO);
       builder.space();
       boolean afterFirstToken = false;
diff --git a/core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java b/core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java
index c7142b793..3e4e175e6 100644
--- a/core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java
+++ b/core/src/test/java/com/google/googlejavaformat/java/FormatterIntegrationTest.java
@@ -48,7 +48,16 @@ public class FormatterIntegrationTest {
 
   private static final ImmutableMultimap<Integer, String> VERSIONED_TESTS =
       ImmutableMultimap.<Integer, String>builder()
-          .putAll(14, "I477", "Records", "RSLs", "Var", "ExpressionSwitch", "I574", "I594")
+          .putAll(
+              14,
+              "I477",
+              "Records",
+              "RSLs",
+              "Var",
+              "ExpressionSwitch",
+              "I574",
+              "I594",
+              "SwitchComment")
           .putAll(15, "I603")
           .putAll(16, "I588", "Sealed")
           .putAll(17, "I683", "I684", "I696")
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.input b/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.input
new file mode 100644
index 000000000..f43acd351
--- /dev/null
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.input
@@ -0,0 +1,31 @@
+class T {
+  void f(String v) {
+    int x =
+        switch (v) {
+            // this is a line comment about "zero"
+          case "zero" -> 0;
+          case "one" ->
+              // this is a line comment about "one"
+              1;
+          case "two" -> // this is a line comment about "two"
+              2;
+          default -> -1;
+        };
+  }
+
+  void g(String v) {
+    int x =
+        switch (v) {
+            // this is a line comment about "zero"
+          case "zero":
+              return 0;
+          case "one":
+            // this is a line comment about "one"
+            return 1;
+          case "two": // this is a line comment about "two"
+            return 2;
+          default:
+            return -1;
+        };
+  }
+}
\ No newline at end of file
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.output b/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.output
new file mode 100644
index 000000000..ff4753b1e
--- /dev/null
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/SwitchComment.output
@@ -0,0 +1,31 @@
+class T {
+  void f(String v) {
+    int x =
+        switch (v) {
+          // this is a line comment about "zero"
+          case "zero" -> 0;
+          case "one" ->
+              // this is a line comment about "one"
+              1;
+          case "two" -> // this is a line comment about "two"
+              2;
+          default -> -1;
+        };
+  }
+
+  void g(String v) {
+    int x =
+        switch (v) {
+            // this is a line comment about "zero"
+          case "zero":
+            return 0;
+          case "one":
+            // this is a line comment about "one"
+            return 1;
+          case "two": // this is a line comment about "two"
+            return 2;
+          default:
+            return -1;
+        };
+  }
+}