PHPStan assumes function/method returns value even if it can throw an exception

[DaveLiddament]

Bug report

Referring the the code snippet... It appears that PHPStan assumes that $person is always set. Given the method createPersonButCouldFail can throw an exception (and is annotated with @throws), this will not always be the case.

Code snippet that reproduces the problem

https://phpstan.org/r/671b1297-7856-4edf-871f-8f9e1d4f7169

Expected output

Expect 2 outcomes:

1. Issue currently reported on line 22 (If condition is always true) is not reported
2. An issue is reported on line 27 (Cannot call method aMethod() on Person|null.)

[DaveLiddament]

A better code snippet might be this: https://phpstan.org/r/cbd2c0cb-5b13-44e8-af1d-ce3bc6984456
In this case createPersonButCouldFail will create a Person object sometimes and throw exceptions other times.

Also if you look at this snippet (https://phpstan.org/r/ee4105dd-a1a1-45a8-9f44-ed1dd0cd03d9) it looks like PHPStan is half right. It knows that person2 is always null in the finally block. But not outside.

[ondrejmirtes]

Similar problems: #2969, #3004

[muglug]

An issue is reported on line 27 (Cannot call method aMethod() on Person|null.)

This is wrong – that line won't be reached if the try block fails

[DaveLiddament]

I agree with @muglug, I am wrong about line 27. Please ignore that part of bug report. Sorry about about that.

However line 22 is still an issue: https://phpstan.org/r/fc66daf3-efad-4edf-8a96-72dbd56e81b9

[scaytrase]

https://phpstan.org/r/b3328236-bda4-4ebb-92c3-7ada868b1d84 I bring my own example too.

[phpstan-bot]

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

@@ @@
-22: If condition is always true.
+No errors

[phpstan-bot]

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

@@ @@
-26: If condition is always true.
+No errors

[phpstan-bot]

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

@@ @@
 27: Unreachable statement - code above always terminates.
-29: If condition is always true.
 32: If condition is always false.
 38: Unreachable statement - code above always terminates.

Full report

Line	Error
27	Unreachable statement - code above always terminates.
32	If condition is always false.
38	Unreachable statement - code above always terminates.

[phpstan-bot]

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

@@ @@
-22: If condition is always true.
+No errors

[phpstan-bot]

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

@@ @@
-21: Else branch is unreachable because ternary operator condition is always true.
-21: Strict comparison using !== between string and null will always evaluate to true.
+No errors

[ondrejmirtes]

Fixed by: phpstan/phpstan-src#481

[github-actions]

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