Indent trailing comments on "{" consistently (fixes #1260)

core/src/main/java/com/google/googlejavaformat/java/JavaInputAstVisitor.java

@@ -564,7 +564,8 @@ private boolean visitArrayInitializer(List<? extends ExpressionTree> expressions
       boolean allowFilledElementsOnOwnLine = shortItems || !inMemberValuePair;
 
       builder.open(plusTwo);
-      tokenBreakTrailingComment("{", plusTwo);
+      // Same as visitBlock (#1260): avoid double plusTwo when elements are present.
+      tokenBreakTrailingComment("{", expressions.isEmpty() ? plusTwo : ZERO);
       boolean hasTrailingComma = hasTrailingToken(builder.getInput(), expressions, ",");
       builder.breakOp(hasTrailingComma ? FillMode.FORCED : FillMode.UNIFIED, "", ZERO);
       if (allowFilledElementsOnOwnLine) {
@@ -2317,7 +2318,12 @@ private void visitBlock(
     } else {
       builder.open(ZERO);
       builder.open(plusTwo);
-      tokenBreakTrailingComment("{", plusTwo);
+      // Inside plusTwo already. Empty blocks still need plusTwo so a trailing comment on "{"
+      // lands inside the braces; non-empty blocks use ZERO so the comment lines up with
+      // statements (otherwise the first format over-indents and a second pass corrects it —
+      // #1260).
+      tokenBreakTrailingComment(
+          "{", node.getStatements().isEmpty() ? plusTwo : ZERO);
       if (allowLeadingBlankLine == AllowLeadingBlankLine.NO) {
         builder.blankLineWanted(BlankLineWanted.NO);
       } else {

core/src/test/java/com/google/googlejavaformat/java/FormatterTest.java

@@ -669,4 +669,40 @@ void f() {
             }
             """);
   }
+
+  @Test
+  public void trailingCommentAfterOpenBraceIsIdempotent() throws Exception {
+    // Regression for #1260: trailing block comments on "{" were indented an extra
+    // plusTwo when the opener was already inside an open(plusTwo) level.
+    String input =
+        """
+        class T {
+          void f() {
+            { /* c */ int x = 1; }
+          }
+
+          int[] a = { /* c */ 1 };
+        }
+        """;
+    String once = new Formatter().formatSource(input);
+    String twice = new Formatter().formatSource(once);
+    assertThat(once).isEqualTo(twice);
+    assertThat(once)
+        .isEqualTo(
+            """
+            class T {
+              void f() {
+                {
+                  /* c */
+                  int x = 1;
+                }
+              }
+
+              int[] a = {
+                /* c */
+                1
+              };
+            }
+            """);
+  }
 }

core/src/test/resources/com/google/googlejavaformat/java/testdata/I1260.input

@@ -0,0 +1,14 @@
+class I1260 {
+  void block() {
+    { /* trailing on open brace */ int x = 1; }
+  }
+
+  void switchCase() {
+    switch (0) {
+      case 1: { /* Break so we don't hit fall-through warning: */ break;/* ignore STRING */
+      }
+    }
+  }
+
+  int[] array = { /* trailing on array brace */ 1, 2 };
+}

core/src/test/resources/com/google/googlejavaformat/java/testdata/I1260.output

@@ -0,0 +1,23 @@
+class I1260 {
+  void block() {
+    {
+      /* trailing on open brace */
+      int x = 1;
+    }
+  }
+
+  void switchCase() {
+    switch (0) {
+      case 1:
+        {
+          /* Break so we don't hit fall-through warning: */
+          break; /* ignore STRING */
+        }
+    }
+  }
+
+  int[] array = {
+    /* trailing on array brace */
+    1, 2
+  };
+}