False positive TypeDoesNotContainType with try/finally

[arjenm]

We have some transactional code which can be simplified to the below example.

https://psalm.dev/r/903fc6c2ed

The $success = true at the end of the try-block is not guaranteed to execute in relation to the statement in the finally, so its value is not always true.
This issue occurred in 3.17, i.e. it in 3.16 it either not checked or was not reporting this false positive.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/903fc6c2ed

<?php

class TestMe {
    private function startTransaction(): void {
    }
    
    private function endTransaction(bool $commit): void {
        echo $commit ? "Committing" : "Rolling back";
    }
    
    public function doWork(): void {
        $this->startTransaction();
        try {
            // It doesn't really matter what happens here
            // Or if several statements to external classes are executed
            $this->workThatMayOrMayNotThrow();

            // This stament is not guarenteed to execute
            $success = true;
        } finally {
            // Whereas this one is
            $this->endTransaction($success ?? false);
        }
    }
    
    private function workThatMayOrMayNotThrow(): void {
        
    }
}

Psalm output (using commit b4a2391):

ERROR: TypeDoesNotContainType - 22:35 - true is always defined and non-null

[muglug]

Now fixed, but you can also rewrite that code: https://psalm.dev/r/795b8567d6

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/795b8567d6

<?php

class TestMe {
    private function startTransaction(): void {
    }
    
    private function endTransaction(bool $commit): void {
        echo $commit ? "Committing" : "Rolling back";
    }
    
    public function doWork(): void {
        $this->startTransaction();
        $success = false;
        try {
            // It doesn't really matter what happens here
            // Or if several statements to external classes are executed
            $this->workThatMayOrMayNotThrow();

            // This stament is not guarenteed to execute
            $success = true;
        } finally {
            // Whereas this one is
            $this->endTransaction($success);
        }
    }
    
    private function workThatMayOrMayNotThrow(): void {
        
    }
}

Psalm output (using commit 7c5feb2):

No issues!