Undesirable error "function should return false/true but returns bool"

[udavka]

Bug report

An error "Anonymous function should return false but returns bool." occurs when a mix of some operations and comparisons are used. The given example may look strange, but it is a smallest code fragment, which gives the error. Of course, in the real code false and true values are possible, but when PHPStan thinks that the calculated result must be false or true only, it emits an error.

Code snippet that reproduces the problem

https://phpstan.org/r/2b8bcf0b-4486-4b1f-a291-2a61e1431613

Expected output

No errors

[phpstan-bot]

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

@@ @@
-14: Anonymous function should return false but returns bool.
+ 5: Method HelloWorld::check() should return bool but return statement is missing.

Full report

Line	Error
5	Method HelloWorld::check() should return bool but return statement is missing.

[neclimdul]

was pretty sure I wasn't going to be able to find a bug for this but here it is!

Ran into this and my test case looks very similar. There are a couple tests here because what triggers this is both both repeatable but also kinda inconsistent and I wasn't able rationalize it.
https://phpstan.org/r/5752d2d4-f8fe-4aeb-9000-2698fa2f75b7

[phpstan-bot]

@neclimdul After the latest push in 1.9.x, PHPStan now reports different result with your code snippet:

@@ @@
+PHP 7.2 – 8.1
+==========
+
+No errors
+
+PHP 7.1 (2 errors)
+==========
+
 32: Anonymous function should return true but returns bool.
 42: Anonymous function should return true but returns bool.

Full report

PHP 7.2 – 8.1

No errors

PHP 7.1 (2 errors)

Line	Error
32	Anonymous function should return true but returns bool.
42	Anonymous function should return true but returns bool.

[phpstan-bot]

@udavka After the latest push in 1.9.x, PHPStan now reports different result with your code snippet:

@@ @@
-14: Anonymous function should return false but returns bool.
+No errors

[phpstan-bot]

@neclimdul After the latest push in 1.9.x, PHPStan now reports different result with your code snippet:

@@ @@
-32: Anonymous function should return true but returns bool.
-42: Anonymous function should return true but returns bool.
+No errors

[github-actions]

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