From 2bb67ce8cd326dbaccbdec97e7578985f6009a14 Mon Sep 17 00:00:00 2001
From: Klaus Hott Vidal <klahott@gmail.com>
Date: Fri, 10 Jul 2026 03:48:01 +1200
Subject: [PATCH] Preserving comments' `placement` property (#19567)

Co-authored-by: fisker <lionkay@gmail.com>
---
 changelog_unreleased/misc/19567.md                         | 3 +++
 src/main/comments/attach.js                                | 7 +++++--
 .../__tests__/__snapshots__/debug-print-comments.js.snap   | 3 +++
 3 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 changelog_unreleased/misc/19567.md

diff --git a/changelog_unreleased/misc/19567.md b/changelog_unreleased/misc/19567.md
new file mode 100644
index 000000000..5ac721126
--- /dev/null
+++ b/changelog_unreleased/misc/19567.md
@@ -0,0 +1,3 @@
+#### Preserving comments' `placement` property (#19567 by @Janther)
+
+Prettier@3.9.0 deleted an undocumented property on comments, which was already used by plugins, `comment.placement` is now available again after comment attach.
diff --git a/src/main/comments/attach.js b/src/main/comments/attach.js
index e5c6481d4..824a4b2c2 100644
--- a/src/main/comments/attach.js
+++ b/src/main/comments/attach.js
@@ -174,11 +174,11 @@ function attachComments(ast, options) {
     }
 
     if (attachPropertiesToComment) {
-      comment.placement = placement;
       comment.enclosingNode = enclosingNode;
       comment.precedingNode = precedingNode;
       comment.followingNode = followingNode;
     }
+    comment.placement = placement;
 
     if (placement === "ownLine") {
       // If a comment exists on its own line, prefer a leading comment.
@@ -256,7 +256,10 @@ function attachComments(ast, options) {
       delete comment.precedingNode;
       delete comment.enclosingNode;
       delete comment.followingNode;
-      delete comment.placement;
+
+      // The `placement` property already used by plugins, can't delete
+      // https://github.com/prettier-solidity/prettier-plugin-solidity/blob/6986134753d72095bde41fe8e9a3c795830282ea/src/slang-nodes/IfStatement.ts#L56
+      // https://github.com/dangmai/prettier-plugin-apex/blob/ff35044e53e0ba30423e1f2030161d096e99ae99/packages/prettier-plugin-apex/src/printer.ts#L251
     }
   }
 }
diff --git a/tests/integration/__tests__/__snapshots__/debug-print-comments.js.snap b/tests/integration/__tests__/__snapshots__/debug-print-comments.js.snap
index bec3f81ed..647afcc39 100644
--- a/tests/integration/__tests__/__snapshots__/debug-print-comments.js.snap
+++ b/tests/integration/__tests__/__snapshots__/debug-print-comments.js.snap
@@ -12,6 +12,7 @@ exports[`prints information for debugging comment attachment with --debug-print-
       "start": { "line": 1, "column": 0, "index": 0 },
       "end": { "line": 1, "column": 7, "index": 7 }
     },
+    "placement": "endOfLine",
     "leading": true,
     "trailing": false,
     "nodeDescription": "ExpressionStatement"
@@ -25,6 +26,7 @@ exports[`prints information for debugging comment attachment with --debug-print-
       "start": { "line": 2, "column": 16, "index": 24 },
       "end": { "line": 2, "column": 23, "index": 31 }
     },
+    "placement": "remaining",
     "leading": false,
     "trailing": true,
     "nodeDescription": "Identifier foo"
@@ -38,6 +40,7 @@ exports[`prints information for debugging comment attachment with --debug-print-
       "start": { "line": 2, "column": 26, "index": 34 },
       "end": { "line": 2, "column": 30, "index": 38 }
     },
+    "placement": "remaining",
     "leading": false,
     "trailing": true,
     "nodeDescription": "ExpressionStatement"