mirror of
https://github.com/danog/psalm-insane-comparison.git
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88 lines
2.0 KiB
Markdown
88 lines
2.0 KiB
Markdown
# psalm-insane-comparison
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A [Psalm](https://github.com/vimeo/psalm) plugin to detect code susceptible to change behaviour with the introduction of [PHP RFC: Saner string to number comparisons](https://wiki.php.net/rfc/string_to_number_comparison)
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Installation:
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```console
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$ composer require --dev orklah/psalm-insane-comparison
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$ vendor/bin/psalm-plugin enable orklah/psalm-insane-comparison
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```
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Usage:
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Run your usual Psalm command:
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```console
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$ vendor/bin/psalm
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```
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Explanation:
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Before PHP8, comparison between a non-empty-string and the literal int 0 resulted in `true`. This is no longer the case with the [PHP RFC: Saner string to number comparisons](https://wiki.php.net/rfc/string_to_number_comparison).
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```php
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$a = 'banana';
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$b = 0;
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if($a == $b){
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echo 'PHP 7 will display this';
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}
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else{
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echo 'PHP 8 will display this instead';
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}
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```
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This plugin helps identify those case to check them before migrating.
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You can solve this issue in a lot of ways:
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- use strict equality:
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```php
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$a = 'banana';
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$b = 0;
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if($a === $b){
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echo 'This is impossible';
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}
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else{
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echo 'PHP 7 and 8 will both display this';
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}
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```
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- use a cast to make both operands the same type:
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```php
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$a = 'banana';
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$b = 0;
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if((int)$a == $b){
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echo 'PHP 7 and 8 will both display this';
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}
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else{
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echo 'This is impossible';
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}
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```
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```php
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$a = 'banana';
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$b = 0;
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if($a == (string)$b){
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echo 'This is impossible';
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}
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else{
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echo 'PHP 7 and 8 will both display this';
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}
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```
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- Make psalm understand you're working with positive-ints when the int operand is not a literal:
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```php
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$a = 'banana';
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/** @var positive-int $b */
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if($a == $b){
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echo 'This is impossible';
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}
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else{
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echo 'PHP 7 and 8 will both display this';
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}
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```
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- Make psalm understand you're working with numeric-strings when the string operand is not a literal:
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```php
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/** @var numeric-string $a */
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$b = 0;
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if($a == $b){
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echo 'PHP 7 and 8 will both display this depending on the value of $a';
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}
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else{
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echo 'PHP 7 and 8 will both display this depending on the value of $a';
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}
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```
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