✨ PHP 8.2 | New PHPCompatibility.TextStrings.RemovedDollarBraceStringEmbeds sniff

[jrfnl]

PHP 8.2 will be deprecating two out of the four ways to embed variables and expressions in text strings (heredocs and double quoted strings).

PHP allows embedding variables in strings with double-quotes (") and heredoc in various ways.

1. Directly embedding variables (“$foo”)
2. Braces outside the variable (“{$foo}”)
3. Braces after the dollar sign (“${foo}”)
4. Variable variables (“${expr}”, equivalent to (string) ${expr})

Options 1 and 2 have their pros and cons. Options 3 and 4 are easily confused due to overlapping syntax, 3 is strictly less capable than 1 and 2, and 4 has completely different semantics (variable variables) that are rarely useful in string interpolation.

This RFC proposes to deprecate options 3 and 4 in PHP 8.2 and remove them in PHP 9.0.

This commit introduces a new sniff to detect this deprecation.

Analyzing code for this deprecation was affected by a bug in the PHPCS Tokenizer discovered while writing this sniff. As of PHPCSUtils 1.0.0-alpha4, the utility methods in PHPCSUtils include a work-around for this bug and are stable for our purposes.

Also note that while the included unit tests should absolutely be sufficient for our purposes, the PHPCSUtils methods used to retrieve embedded variables and expressions are tested in-depth (> 1000 tests for that functionality alone), so we should be good ;-)

Last note: the tests are split in two files as any code after a PHP 7.3 heredoc/nowdoc will not tokenize correctly on PHP < 7.3. Splitting the tests into two files works as a work-around for that.

Includes unit tests.
Includes sniff documentation.

Refs:

• https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation
• [RFC] Deprecate ${} string interpolation php/php-src#8212
• https://www.php.net/manual/en/language.types.string.php#language.types.string.parsing
• https://gist.github.com/iluuu1994/72e2154fc4150f2258316b0255b698f2
• Tokenizer/PHP: bug fix for double quoted strings using ${ squizlabs/PHP_CodeSniffer#3604

Related to #1348

[divinity76]

seems it cannot generate diff-fixes (--report=diff) thought 🤔

[jrfnl]

@divinity76 Nearly all things flagged by PHPCompatibility will need a dev's attention to decide what and how to fix it, so no, you will not see auto-fixers included in these sniffs and rightfully so (with only one or two exceptions).

[divinity76]

@jrfnl an automatic fixer has been made for Rector: rectorphp/rector-src#5781

Edit : but Rector is a project with substantial infrastructure for this sort of task, and aligns perfectly with the Rector project goals

[jrfnl]

@divinity76 Good to know.