False positive with assert-if-true/if-false

[klimick]

If assert function has @psalm-assert-if-false and @psalm-assert-if-true at the same time then it works incorrectly:
https://psalm.dev/r/91745556ee

Quick workaround is drop @psalm-assert-if-false or @psalm-assert-if-true from assert function:
https://psalm.dev/r/a5500b4ed2

But above workaround doesn't work in more difficult cases:
https://psalm.dev/r/408248f46f

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/91745556ee

<?php

/**
 * @psalm-assert-if-false string $value
 * @psalm-assert-if-true int $value
 */
function isRight(string|int $value): bool
{
	return is_int($value);
}

function testRight(int $v): void {}
function testLeft(string $v): void {}

/** @var int|string */
$value = 0;

isRight($value)
    ? testRight($value)
    : testLeft($value);

if (isRight($value)) {
    testRight($value);
} else {
    testLeft($value);
}

!isRight($value)
    ? testLeft($value)
    : testRight($value);

if (!isRight($value)) {
    testLeft($value);
} else {
    testRight($value);
}

Psalm output (using commit e93e532):

ERROR: InvalidScalarArgument - 20:16 - Argument 1 of testLeft expects string, int|string provided

ERROR: InvalidScalarArgument - 25:14 - Argument 1 of testLeft expects string, int|string provided

ERROR: InvalidScalarArgument - 29:16 - Argument 1 of testLeft expects string, int|string provided

ERROR: InvalidScalarArgument - 33:14 - Argument 1 of testLeft expects string, int|string provided

https://psalm.dev/r/a5500b4ed2

<?php

/**
 * @psalm-assert-if-true int $value
 */
function isRight(string|int $value): bool
{
	return is_int($value);
}

function testRight(int $v): void {}
function testLeft(string $v): void {}

/** @var int|string */
$value = 0;

isRight($value)
    ? testRight($value)
    : testLeft($value);

if (isRight($value)) {
    testRight($value);
} else {
    testLeft($value);
}

!isRight($value)
    ? testLeft($value)
    : testRight($value);

if (!isRight($value)) {
    testLeft($value);
} else {
    testRight($value);
}

Psalm output (using commit e93e532):

No issues!

https://psalm.dev/r/408248f46f

<?php

/**
 * @template L
 * @template R
 */
interface Either {}

/**
 * @template R
 * @implements Either<empty, R>
 */
final class Right implements Either {}

/**
 * @template L
 * @implements Either<L, empty>
 */
final class Left implements Either {}

/**
 * @template L
 * @template R
 *
 * @param Either<L, R> $either
 * @return bool
 *
 * @psalm-assert-if-true Left<L> $either
 * @psalm-assert-if-false Right<L> $either
 */
function isLeft(Either $either): bool
{
	throw new RuntimeException('???');
}

/** @var Either<int, string> $either */
$either = null;

if (!isLeft($either)) {
    /** @psalm-trace $left */
	$left = $either;
} else {
	/** @psalm-trace $right */
	$right = $either;
}

Psalm output (using commit e93e532):

INFO: Trace - 41:2 - $left: Either<int, string>

INFO: Trace - 44:2 - $right: Left<int>

[weirdan]

Also this doesn't seem right: https://psalm.dev/r/65cbc43cff

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/65cbc43cff

<?php

/** @psalm-assert-if-true string $value */
function isString(mixed $value): bool {
	return is_string($value);
}


/** @var int|string */
$value = 0;

if (!isString($value)) {
    /** @psalm-trace $value */; // should be int|string, as predicate does not declare anything for false
}

Psalm output (using commit e93e532):

INFO: Trace - 13:31 - $value: int

[weirdan]

@muglug it looks like Psalm generates inverted assertion (!string) for false return here, but should it really do that?

[whsv26]

The same problem for Either monad. I'd like to do something like this, but unfortunately it's not working for both psalm-assert-if-true and psalm-assert-if-false at the same time.

/**
 * @psalm-assert-if-true Left<L, R> $this
 * @psalm-assert-if-false Right<L, R> $this
 */
public function isLeft(): bool {}

/**
 * @psalm-assert-if-true Right<L, R> $this
 * @psalm-assert-if-false Left<L, R> $this
 */
public function isRight(): bool {}

[klimick]

Issue is solved: https://psalm.dev/r/b0b6a03bd6
It seems in the #9209

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/b0b6a03bd6

<?php

/**
 * @template L
 * @template R
 */
interface Either {}

/**
 * @template R
 * @implements Either<never, R>
 */
final class Right implements Either {
    /**
     * @return R
     */
    public function get(): mixed {throw new \RuntimeException('???');}
}

/**
 * @template L
 * @implements Either<L, never>
 */
final class Left implements Either {
    /**
     * @return L
     */
    public function get(): mixed {throw new \RuntimeException('???');}
}

/**
 * @template L
 * @template R
 *
 * @param Either<L, R> $either
 * @return bool
 *
 * @psalm-assert-if-true Left<L> $either
 * @psalm-assert-if-false Right<L> $either
 */
function isLeft(Either $either): bool
{
	throw new RuntimeException('???');
}

/** @var Either<int, string> $either */;

if (isLeft($either)) {
    $_int = $either->get();
    /** @psalm-check-type $_int = int */
} else {
	$_string = $either->get();
    /** @psalm-check-type $_string = int */
}

Psalm output (using commit d450b40):

No issues!

[klimick]

I hastened to close the issue. Sorry. Issue still exists.
https://psalm.dev/r/6125f6ef36

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/6125f6ef36

<?php

/**
 * @template L
 * @template R
 */
abstract class Either
{
	/**
     * @psalm-assert-if-false Right<R> $this
     * @psalm-assert-if-true Left<L> $this
     */
     public function isLeft(): bool
     {
	     throw new RuntimeException('???');
     }
}

/**
 * @template R
 * @extends Either<never, R>
 */
final class Right extends Either {
    /**
     * @return R
     */
    public function get(): mixed {throw new \RuntimeException('???');}
}

/**
 * @template L
 * @extends Either<L, never>
 */
final class Left extends Either {
    /**
     * @return L
     */
    public function get(): mixed {throw new \RuntimeException('???');}
}

/** @var Either<int, string> $either */;

if ($either->isLeft()) {
    $_int = $either->get();
    /** @psalm-trace $either */;
} else {
	$_string = $either->get();
    /** @psalm-trace $either */;
}

Psalm output (using commit d450b40):

INFO: Trace - 45:32 - $either: Left<int>

ERROR: PossiblyUndefinedMethod - 47:22 - Method Either::get does not exist

INFO: Trace - 48:32 - $either: Either<int, string>|Right<string>

[kkmuffme]

@weirdan this is from #9209

Afaik the original PR for this #9064 does not have this bug, I guess the conditions removed in 9209 were actually not unnecessary? Perhaps should have merged 9064 instead? (since it also fixes #9037)