Single-statement inline offset updates cause confusion

[judahnator]

Bug report

When comparing two expressions using an incremented value of the same variable as an offset, PHPStan does not see that the offset will change within the comparison and throws an error.

Code snippet that reproduces the problem

The code snippet in my project with this error is as follows:

do {
    // snip
} while ($tokens->readOne(++$offset) instanceof CommaToken && $tokens->readOne(++$offset) instanceof IdentityToken);

However, I can also reproduce this on the playground.

https://phpstan.org/r/6b705626-659e-4753-94a5-756e167526e7

The error given is always a variation of:

• Result of && is always false.
• Right side of && is always true.

Expected output

In both examples, since $offset is different in both cases it is possible for both sides of the && to be independent. PHPStan is acting as if it believes that both of the values here are the same.

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[phpstan-bot]

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

@@ @@
-8: Right side of && is always true.
+8: Offset 1|int<3, max> does not exist on array{}.

Full report

Line	Error
8	`Offset 1

[github-actions]

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