Array unions are improperly collapsed

[gnarlyquack]

Bug report

array{a, b}|array{c, d} is improperly collapsed as array{a|c, b|d}

Code snippet that reproduces the problem

https://phpstan.org/r/2fe252ba-d874-4f42-9164-d5672993d555

Expected output

Line 10: No error
Line 30: Function do_foo() should return array(true, null)|array(null, true) but returns ....
Actually, something (else) weird seems to be going on in line 30 since the reported "actual" type doesn't seem to make any sense.

[gnarlyquack]

Actually, this seems to be an issue with array unions in general:
https://phpstan.org/r/794c728c-a1a8-4dee-8c80-42fcd9907ac8
I would expect an error on line 8 but, as can be seen on line 17, PHPStan is ok with a mixed array being returned.

I think my original message may have misemphasized the issue: the concern isn't just that the returned array type isn't deduced from the typecheck, but that an error isn't raised when an array of incorrect type is returned:
https://phpstan.org/r/9dbdde14-c59b-41db-a54b-7fdee611037a
I would expect errors on lines 15 and 19.

[ondrejmirtes]

Hi, just a heads-up - I consider this a feature request, with such complex needs you'd be much better served modeling your types as objects.

[gnarlyquack]

I would consider it, but I'm getting bit by #3034
https://phpstan.org/r/3d46f2f0-cf4a-4a48-8a19-3a990a8dd93d
https://phpstan.org/r/658abac8-0972-4537-a51e-9f4200929c1d

[phpstan-bot]

@gnarlyquack PHPStan now reports different result with your code snippet:

@@ @@
 45: Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array(string)>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return typehint.
65	`Function foo\bar() should return foo\Error<array>

[phpstan-bot]

@gnarlyquack PHPStan now reports different result with your code snippet:

@@ @@
 45: Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array(string)>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return typehint.
65	`Function foo\bar() should return foo\Error<array<int, string>>

[Seldaek]

Another example for this feature request https://phpstan.org/r/14283564-cafe-450f-a734-ab6188da40d8 - bit me while trying to type the write() function here https://github.com/Seldaek/monolog/blob/main/src/Monolog/Handler/AbstractProcessingHandler.php#L40 which accepts a record array with the addition of a formatted key.

Not a huge deal, I duplicated the record array in this one special instance, but would have been neat if it just worked :) And yes I can see the argument that records should be objects perhaps, but they've been arrays for 11+ years and there's lots of code working with that assumption.

[phpstan-bot]

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

@@ @@
-45: Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+45: Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return type.
+65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array(string)>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return type.
65	`Function foo\bar() should return foo\Error<array>

[phpstan-bot]

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

@@ @@
-45: Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+45: Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return type.
+65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array(string)>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return type.
65	`Function foo\bar() should return foo\Error<array<int, string>>

[phpstan-bot]

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

@@ @@
 10: Parameter #1 $flag of function do_bar expects bool, true|null given.
-30: Function do_foo() should return array(true|null, true|null) but returns array(null, int<1, max>).
+30: Function do_foo() should return array{true|null, true|null} but returns array{null, int<1, max>}.

Full report

Line	Error
10	`Parameter #1 $flag of function do_bar expects bool, true
30	`Function do_foo() should return array{true

[phpstan-bot]

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

@@ @@
-45: Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+45: Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return type.
+65: Function foo\bar() should return foo\Error<array<string>>|foo\Success<bool> but returns foo\Error<array{string}>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<string>> so it can be removed from the return type.
65	`Function foo\bar() should return foo\Error<array>

[phpstan-bot]

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

@@ @@
-45: Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return typehint.
-65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array<int, string>>.
+45: Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return type.
+65: Function foo\bar() should return foo\Error<array<int, string>>|foo\Success<bool> but returns foo\Error<array{string}>.

Full report

Line	Error
45	Function foo\bar() never returns foo\Error<array<int, string>> so it can be removed from the return type.
65	`Function foo\bar() should return foo\Error<array<int, string>>

[phpstan-bot]

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

@@ @@
 10: Parameter #1 $flag of function do_bar expects bool, true|null given.
-30: Function do_foo() should return array(true|null, true|null) but returns array(null, int<1, max>).
+30: Function do_foo() should return array{null, true}|array{true, null} but returns array{null, int<1, max>}.

Full report

Line	Error
10	`Parameter #1 $flag of function do_bar expects bool, true
30	`Function do_foo() should return array{null, true}

[phpstan-bot]

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

@@ @@
-No errors
+ 7: Function do_foo() never returns array{null, bool} so it can be removed from the return type.
+15: Function do_foo() should return array{bool, null}|array{null, bool} but returns array{false, true}.
+19: Function do_foo() should return array{bool, null}|array{null, bool} but returns array{false, false}.

Full report

Line	Error
7	Function do_foo() never returns array{null, bool} so it can be removed from the return type.
15	`Function do_foo() should return array{bool, null}
19	`Function do_foo() should return array{bool, null}

[gnarlyquack]

Hi,

Thanks for working on this.

This appears to fix the specific error on line 30 in the original code snippet, but in general this still doesn't seem to be working correctly:

https://phpstan.org/r/794c728c-a1a8-4dee-8c80-42fcd9907ac8
Line 17 is now being properly flagged, but line 8 isn't. It's allowing a mixed array of ints and strings to be returned, when it should either be an array of ints or an array of strings.

Same thing here:
https://phpstan.org/r/9dbdde14-c59b-41db-a54b-7fdee611037a
Lines 15 and 19 should both be errors.

I also see that in line 10 of the original snippet, the type of $result is still not being correctly determined. If $error isn't set (i.e., null), then $result must be a bool, so there shouldn't be an error.
https://phpstan.org/r/9ebf73e8-cf62-4339-8779-710e2ba048eb

[github-actions]

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