From a028291f8e5e79b6446ad67ed8b0be9c5ec8f029 Mon Sep 17 00:00:00 2001
From: Christopher Speck <cspeckrun@gmail.com>
Date: Thu, 16 Sep 2021 14:50:01 -0400
Subject: [PATCH] Make corrections to the "arc amend" workflow in Mercurial
 repositories to be compatible with PHP 5+

Summary:
Refs T13665

In the update to D21716 the `str_starts_with` function was added which is only available in PHP 8. This changes it to use `strncmp()` which is compatible back to PHP 4.

Additionally fixed running into an error when trying to run `arc amend` on a commit which already matches the content known in Phabricator. Mercurial throws an error when running `amend` without file changes and using the exact same commit message it already has.

Test Plan:
I created a commit and revision then used `hg amend -e` to modify the commit message locally.
I used `arc amend` to update the commit message back to the appropriate message from Phabricator.
I ran `arc amend` again to verify that the command did not fail even though the commit message is unchanged.

I ran `arc inspect --explore -- 'commit(674492bb460)'` and verified it matched the appropriate commit, to verify the substring matching works properly.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T13665

Differential Revision: https://secure.phabricator.com/D21723
---
 .../ArcanistMercurialCommitSymbolCommitHardpointQuery.php    | 2 +-
 src/repository/api/ArcanistMercurialAPI.php                  | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/ref/commit/ArcanistMercurialCommitSymbolCommitHardpointQuery.php b/src/ref/commit/ArcanistMercurialCommitSymbolCommitHardpointQuery.php
index b561247d..db27e8fb 100644
--- a/src/ref/commit/ArcanistMercurialCommitSymbolCommitHardpointQuery.php
+++ b/src/ref/commit/ArcanistMercurialCommitSymbolCommitHardpointQuery.php
@@ -159,7 +159,7 @@ final class ArcanistMercurialCommitSymbolCommitHardpointQuery
     // a spot which a marker might match.
     foreach ($node_list as $node) {
       foreach ($symbol_set as $symbol) {
-        if (str_starts_with($node, $symbol)) {
+        if (strncmp($node, $symbol, strlen($symbol)) === 0) {
           if (!isset($hash_map[$symbol])) {
             $hash_map[$symbol] = $node;
           }
diff --git a/src/repository/api/ArcanistMercurialAPI.php b/src/repository/api/ArcanistMercurialAPI.php
index df6bdc1c..7e35a1e3 100644
--- a/src/repository/api/ArcanistMercurialAPI.php
+++ b/src/repository/api/ArcanistMercurialAPI.php
@@ -672,7 +672,10 @@ final class ArcanistMercurialAPI extends ArcanistRepositoryAPI {
   public function amendCommit($message = null) {
     $path_statuses = $this->buildUncommittedStatus();
 
-    if ($message === null) {
+    $existing_message = $this->getCommitMessage(
+      $this->getWorkingCopyRevision());
+
+    if ($message === null || $message == $existing_message) {
       if (empty($path_statuses)) {
         // If there are no changes to the working directory and the message is
         // not being changed then there's nothing to amend. Notably Mercurial