Deprecate magic default values

Author: morozov

UPGRADE.md

@@ -8,6 +8,11 @@ awareness about deprecated code.
 
 # Upgrade to 4.4
 
+## Deprecated using current date, time and timestamp SQL expressions as default values
+
+Using SQL expressions for the current date, time, or timestamp as column default values is deprecated. Instead, use an
+instance of the `CurrentDate`, `CurrentTime`, or `CurrentTimestamp` class, respectively.
+
 ## Deprecated `Schema::createNamespace()` and the `$namespaces` constructor parameter
 
 The `Schema::createNamespace()` method and the `$namespaces` constructor parameter have been deprecated. The schema

src/Platforms/AbstractPlatform.php

@@ -1559,14 +1559,35 @@ public function getDefaultValueDeclarationSQL(array $column): string
         }
 
         if ($type instanceof Types\PhpDateTimeMappingType && $default === $this->getCurrentTimestampSQL()) {
+            Deprecation::trigger(
+                'doctrine/dbal',
+                'https://github.com/doctrine/dbal/pull/7195',
+                'Using "%s" as a column default value is deprecated. Use a CurrentTimestamp instance instead.',
+                $default,
+            );
+
             return ' DEFAULT ' . $this->getCurrentTimestampSQL();
         }
 
         if ($type instanceof Types\PhpTimeMappingType && $default === $this->getCurrentTimeSQL()) {
+            Deprecation::trigger(
+                'doctrine/dbal',
+                'https://github.com/doctrine/dbal/pull/7195',
+                'Using "%s" as a column default value is deprecated. Use a CurrentTime instance instead.',
+                $default,
+            );
+
             return ' DEFAULT ' . $this->getCurrentTimeSQL();
         }
 
         if ($type instanceof Types\PhpDateMappingType && $default === $this->getCurrentDateSQL()) {
+            Deprecation::trigger(
+                'doctrine/dbal',
+                'https://github.com/doctrine/dbal/pull/7195',
+                'Using "%s" as a column default value is deprecated. Use a CurrentDate instance instead.',
+                $default,
+            );
+
             return ' DEFAULT ' . $this->getCurrentDateSQL();
         }