array_pop/array_shift false positive

[dereuromark]

Bug report

array_* false positive

while (count($arguments) > 0) {
	$words .= array_pop($arguments);
	if (count($arguments) > 0) {
		$words .= ' ';
	}
}

Code snippet that reproduces the problem

$arguments = ['x', 'y'];

$words = '';
while (count($arguments) > 0) {
	$words .= array_pop($arguments);
	if (count($arguments) > 0) {
		$words .= ' ';
	}
}

echo $words;

https://phpstan.org/r/172e2161-c350-4466-8867-de074489c34f

Expected output

No error

[ondrejmirtes]

Not sure why is this still happening - /cc @cs278

[cs278]

Reverting phpstan/phpstan-src@b1fd47b results in an error at the if statement:

Comparison operation ">" between 1|2 and 0 is always true.

Which makes sense as the array_pop() now invalidates the known value of count($arguments). At a guess I think PHPStan is only ever seeing the constant array that was initially defined, I suppose the code needs to either pop the element off the constant array or change the type to not be a constant array.

[ondrejmirtes]

There's most likely a bug in handling the while loop.

[cs278]

Hah think I've just found this again.

https://phpstan.org/r/eff591cd-41f7-4e5e-a236-f000f32236d5

Presumably this
https://github.com/phpstan/phpstan-src/blob/e4b71d41de38a83ae4a9dcd2a9bdf342e10f3c3a/src/Analyser/NodeScopeResolver.php#L1849-L1878 should union on an empty array as that is a possible outcome of a array_{shift,pop}() call.

[phpstan-bot]

@cs278 After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
  5: Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
 18: Dumped type: array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'}
 20: Call to function assert() with false will always evaluate to false.
-20: Strict comparison using === between array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'} and array{} will always evaluate to false.
-21: Call to function assert() with false will always evaluate to false.
-21: Strict comparison using === between int<1, max> and 0 will always evaluate to false.
+20: Strict comparison using === between array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'} and array{} will always evaluate to false.

Full report

Line	Error
5	Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
18	`Dumped type: array{0: 1
20	Call to function assert() with false will always evaluate to false.
20	`Strict comparison using === between array{0: 1

[phpstan-bot]

@dereuromark After the latest commit in 1.6.x, PHPStan now reports different result with your code snippet:

@@ @@
- 6: Comparison operation ">" between 1|2 and 0 is always true.
+ 6: Comparison operation ">" between int<1, 2> and 0 is always true.
 13: Unreachable statement - code above always terminates.

Full report

Line	Error
6	Comparison operation ">" between int<1, 2> and 0 is always true.
13	Unreachable statement - code above always terminates.

[Seldaek]

Another one I discovered today due to the changes to DateTime::modify

https://phpstan.org/r/213421a3-bdf9-4ee1-93b9-6e3cc368021a

It seems after an array_shift the whole static array is lost but IMO it should be able to retain the values as a union of static strings?

[phpstan-bot]

@cs278 After the latest push in 1.8.x, PHPStan now reports different result with your code snippet:

@@ @@
  5: Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
-18: Dumped type: array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'}
+18: Dumped type: array{0: 1|(literal-string&non-falsy-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'}
 20: Call to function assert() with false will always evaluate to false.
-20: Strict comparison using === between array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'} and array{} will always evaluate to false.
-21: Call to function assert() with false will always evaluate to false.
-21: Strict comparison using === between int<1, max> and 0 will always evaluate to false.
+20: Strict comparison using === between array{0: 1|(literal-string&non-falsy-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'} and array{} will always evaluate to false.

Full report

Line	Error
5	Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
18	`Dumped type: array{0: 1
20	Call to function assert() with false will always evaluate to false.
20	`Strict comparison using === between array{0: 1

[phpstan-bot]

@Seldaek After the latest push in 1.8.x, PHPStan now reports different result with your code snippet:

@@ @@
  7: Dumped type: array{'+1week', '+1months', '+6months', '+17months'}
- 9: Expected type array<0|1|2|3, '+1week'|'+1months'|'+6months'|'+17months'>, actual: array<0|1|2|3, literal-string&non-empty-string>
+ 9: Expected type array<0|1|2|3, '+1week'|'+1months'|'+6months'|'+17months'>, actual: array<0|1|2|3, literal-string&non-falsy-string>
 10: Cannot call method modify() on DateTimeImmutable|false.

Full report

Line	Error
7	Dumped type: array{'+1week', '+1months', '+6months', '+17months'}
9	`Expected type array<0
10	`Cannot call method modify() on DateTimeImmutable

[phpstan-bot]

@dereuromark After the latest push in 1.8.x, PHPStan now reports different result with your code snippet:

@@ @@
- 6: Comparison operation ">" between 1|2 and 0 is always true.
-13: Unreachable statement - code above always terminates.
+No errors

[phpstan-bot]

@cs278 After the latest push in 1.8.x, PHPStan now reports different result with your code snippet:

@@ @@
  5: Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
-18: Dumped type: array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'}
-20: Call to function assert() with false will always evaluate to false.
-20: Strict comparison using === between array{0: 1|(literal-string&non-empty-string)|false, 1: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'} and array{} will always evaluate to false.
-21: Call to function assert() with false will always evaluate to false.
-21: Strict comparison using === between int<1, max> and 0 will always evaluate to false.
+18: Dumped type: array{0?: 1|(literal-string&non-falsy-string)|false, 1?: 1|'x'|'y', 2?: 'x'|'y', 3?: 'y'}

Full report

Line	Error
5	Method HelloWorld::sayHello() has parameter $input with no value type specified in iterable type iterable.
18	`Dumped type: array{0?: 1

[github-actions]

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