Do not use quotes to represent a boolean default

[morozov]

Q	A
Type	improvement
BC Break	no

Representing boolean default as a string literal may cause false-positive diffs during platform-aware schema comparison if the platform doesn't support boolean columns natively (IBM DB2, Oracle, MySQL) and doesn't implement any hacks for introspection of boolean columns:

dbal/src/Platforms/AbstractMySQLPlatform.php

Line 1052 in 2b3504f

'tinyint' => 'boolean',

dbal/src/Platforms/OraclePlatform.php

Line 1148 in 2b3504f

'pls_integer' => 'boolean',

See #5107 (comment) for more details.

The existing assertions that expect SQL like TINYINT(1) DEFAULT '0' are obviously wrong and were likely implemented by copy/pasting the actual value as expected.

According to the functional tests, there are no cases where a boolean default would have to be represented as a string literal. All supported platforms use integer 0 and 1 to represent boolean values. PostgreSQL supports booleans literals true/false.

Note that the documentation for PostgreSQL 9.3 is the last version that mentions the support for quoted 'true' and 'false' as valid boolean literals.

[SenseException]

The tests with a string default value still work. If there's no test using a boolean default value DEFAULT true, we might need one.

[morozov]

If there's no test using a boolean default value DEFAULT true, we might need one.

I checked that the following test passes with true as well and generates the expected table DDL:

dbal/tests/Functional/Schema/PostgreSQLSchemaManagerTest.php

Lines 300 to 304 in 0edd213

	public function testBooleanDefault(callable $comparatorFactory): void
	{
	$table = new Table('ddc2843_bools');
	$table->addColumn('id', 'integer');
	$table->addColumn('checked', 'boolean', ['default' => false]);

We can update the test separately so it doesn't block merging the patch.