array_merge of known shapes loses type information

[Firehed]

Bug report

Performing an array_merge where two arrays share a known shape results in type loss of the result.

Code snippet that reproduces the problem

Original issue:

https://phpstan.org/r/bc48b3cb-e1f4-4b4a-81ca-d18bf8901104

Simplest form:

https://phpstan.org/r/34b0de0f-a3b6-4ed5-b802-ff500ebbb619

Expected output

No errors, dumpType shows:

Dumped type: array{a: int, b: string}

[staabm]

Its a know problem. I guess a issue is already filled somewhere.

Last time we tried to inprove this case we had to revert because the analysis was that time-intensive that it was not acceptable - phpstan/phpstan-src#622 (comment)

[voku]

There is already a new pull request that (at least in my tests) do not have the performance issue and still fix the array_merge logic: phpstan/phpstan-src#696

[staabm]

fixed by phpstan/phpstan-src#1135

[phpstan-bot]

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

@@ @@
-15: Dumped type: non-empty-array<literal-string&non-empty-string, int|string>
-16: Parameter #1 $s of function useString expects string, int|string given.
-17: Parameter #1 $i of function useInt expects int, int|string given.
+15: Dumped type: array{a: int, b: string}

Full report

Line	Error
15	Dumped type: array{a: int, b: string}

[phpstan-bot]

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

@@ @@
  7: Dumped type: array{a: 1, b: 'bee'}
- 8: Dumped type: non-empty-array<literal-string&non-empty-string, 1|'bee'>
- 9: Parameter #1 $s of function useString expects string, int|string given.
-10: Parameter #1 $i of function useInt expects int, int|string given.
+ 8: Dumped type: array{a: 1, b: 'bee'}

Full report

Line	Error
7	Dumped type: array{a: 1, b: 'bee'}
8	Dumped type: array{a: 1, b: 'bee'}

[ondrejmirtes]

Needs a regression test :) /cc @VincentLanglet

[github-actions]

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