From 81c9bb167dc359b7c6beceb02301302723786f54 Mon Sep 17 00:00:00 2001
From: Ben Davies <ben.davies@gmail.com>
Date: Mon, 21 May 2018 12:49:26 +0100
Subject: [PATCH] correctly produce alter table sql to update column comment
 under postgres

---
 .../DBAL/Platforms/PostgreSqlPlatform.php     | 12 +++++++---
 .../AbstractPostgreSqlPlatformTestCase.php    | 23 +++++++++++++++++++
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
index 2cb0bf56f82..65c96b01c0f 100644
--- a/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
+++ b/lib/Doctrine/DBAL/Platforms/PostgreSqlPlatform.php
@@ -25,8 +25,8 @@
 use Doctrine\DBAL\Schema\Index;
 use Doctrine\DBAL\Schema\Sequence;
 use Doctrine\DBAL\Schema\TableDiff;
-use Doctrine\DBAL\Types\BinaryType;
 use Doctrine\DBAL\Types\BigIntType;
+use Doctrine\DBAL\Types\BinaryType;
 use Doctrine\DBAL\Types\BlobType;
 use Doctrine\DBAL\Types\IntegerType;
 use Doctrine\DBAL\Types\Type;
@@ -591,11 +591,17 @@ public function getAlterTableSQL(TableDiff $diff)
                 }
             }
 
-            if ($columnDiff->hasChanged('comment')) {
+            $oldComment = null;
+            $newComment = $this->getColumnComment($column);
+            if (null !== $columnDiff->fromColumn) {
+                $oldComment = $this->getColumnComment($columnDiff->fromColumn);
+            }
+
+            if ($columnDiff->hasChanged('comment') || (null !== $columnDiff->fromColumn && $oldComment !== $newComment)) {
                 $commentsSQL[] = $this->getCommentOnColumnSQL(
                     $diff->getName($this)->getQuotedName($this),
                     $column->getQuotedName($this),
-                    $this->getColumnComment($column)
+                    $newComment
                 );
             }
 
diff --git a/tests/Doctrine/Tests/DBAL/Platforms/AbstractPostgreSqlPlatformTestCase.php b/tests/Doctrine/Tests/DBAL/Platforms/AbstractPostgreSqlPlatformTestCase.php
index 029092ff340..54da40445bf 100644
--- a/tests/Doctrine/Tests/DBAL/Platforms/AbstractPostgreSqlPlatformTestCase.php
+++ b/tests/Doctrine/Tests/DBAL/Platforms/AbstractPostgreSqlPlatformTestCase.php
@@ -819,6 +819,29 @@ public function testAltersTableColumnCommentWithExplicitlyQuotedIdentifiers()
         );
     }
 
+    /**
+     * @group 3158
+     */
+    public function testAltersTableColumnCommentIfRequiredByType()
+    {
+        $table1 = new Table('"foo"', [new Column('"bar"', Type::getType('datetime'))]);
+        $table2 = new Table('"foo"', [new Column('"bar"', Type::getType('datetime_immutable'))]);
+
+        $comparator = new Comparator();
+
+        $tableDiff = $comparator->diffTable($table1, $table2);
+
+        $this->assertInstanceOf('Doctrine\DBAL\Schema\TableDiff', $tableDiff);
+        $this->assertSame(
+            [
+                'ALTER TABLE "foo" ALTER "bar" TYPE TIMESTAMP(0) WITHOUT TIME ZONE',
+                'ALTER TABLE "foo" ALTER "bar" DROP DEFAULT',
+                'COMMENT ON COLUMN "foo"."bar" IS \'(DC2Type:datetime_immutable)\'',
+            ],
+            $this->_platform->getAlterTableSQL($tableDiff)
+        );
+    }
+
     /**
      * {@inheritdoc}
      */