This release fixes 29 issues!

In other news, we refreshed the on-line playground! You can now set many previously-unavailable config parameters:

This helps you testing out various PHPStan features, and also reproduce issues for bug reports when something goes wrong with these parameters set to their non-default values.

Also, there's a couple of new blogposts on the website:

• Why Array String Keys Are Not Type-Safe in PHP
• Using PHPStan to Extract Data About Your Codebase

Improvements 🔧

• More rules about PHPDoc tags declarations now validate stub files (phpstan/phpstan-src@610537a)

Bugfixes 🐛

• Fix: errors for argument array template types no longer reported (argument.type) (#5300), errors for argument array template types no longer reported (argument.type) #14138, thanks @VincentLanglet and @staabm!
• Fix: Result of function_exists() can't be "cached" (#5303), Result of function_exists() can't be "cached" #14384, thanks @staabm and @VincentLanglet!
• Fix: Optional templated args not provided cause unbound template errors (#5175), Optional templated args not provided cause unbound template errors #2572, Tempated function with variadic argment: Unable to resolve the template type TRest in call to function intersection #7704, Variadic arguments (splat), conditional returns and passing no arguments/empty function call #9360, thanks @staabm and @VincentLanglet!
• Resolve generic parameter defaults that reference other template parameters (#5304), thanks @JanTvrdik!
• Fix: array_filter with assert-if-true callable marks all keys optional (#5097), array_filter with assert-if-true callable marks all keys optional #11730, thanks @staabm and @VincentLanglet!
• Fix: assign.readOnlyProperty (#5061), assign.readOnlyProperty #12253, thanks @VincentLanglet and @staabm!
• Fix: Bogus write-only error when appending to an array-like object in private class property (#5102), Bogus write-only error when appending to an array-like object in private class property #6777, thanks @VincentLanglet and @staabm!
• Fix: Cannot use "T is never" in conditional return (#5082), Cannot use "T is never" in conditional return #9634, Can't check if Iterator is empty #10938, thanks @VincentLanglet and @staabm!
• Fix: [NAN] === mixed is always evaluated as false (#5321), [NAN] === mixed is always evaluated as false #11054, thanks @staabm and @VincentLanglet!
• Fix: Parameter 0.1 release #2 $callback of function uasort expects callable(Foo, Foo): int, 'strnatcasecmp' given. (#5171), Parameter #2 $callback of function uasort expects callable(Foo, Foo): int, 'strnatcasecmp' given. #11619, thanks @VincentLanglet and @staabm!
• Fix: Does not warn about non-nullable class-property (#5327), Does not warn about non-nullable class-property #14393, Useless null coalesce not reported when relying on class property typehint #4846, thanks @VincentLanglet and @staabm!
• Fix: Incorrect inference of instance variable modified from callback (#5347), Incorrect inference of instance variable modified from callback #8926, param-immediately-invoked-callable not working #11417, Setting property in anonymous function is ignored by if.alwaysFalse #10903, thanks @staabm and @VincentLanglet!
• TypeSpecifier: resolve purity/impurity for CallableParametersAcceptor (#5348), Unable to mark an anonymous function as impure #12686, PHPDoc block is ignored for closures/anonymous functions #3770, Closures cannot be marked as impure #6822, thanks @staabm and @VincentLanglet!
• filter_var: Fix throw on failure with require/force array (#5349), thanks @VincentLanglet!
• Fix: FILTER_FLAG_GLOBAL_RANGE constant not "known" on PHP 8.3, 8.4 (#5334), FILTER_FLAG_GLOBAL_RANGE constant not "known" on PHP 8.3, 8.4 #14397, thanks @VincentLanglet and @staabm!
• Fix: Narrowed template on an interface is ignored when generics is not specified (#5339), Narrowed template on an interface is ignored when generics is not specified #9045, iterator_to_array doesn't keep Iterator type #7185, Generic type is not inferred at all when instanceof is used. #13204, thanks @VincentLanglet and @staabm!
• Fix: Consequent scope with the same condition (#5056), Consequest scope with the same condition #4173, Always assigned variable in conditional body branch should be substracted from mutually-exclusive context #12992, "Variable might not be defined" false positive #14227, thanks @VincentLanglet and @staabm!

Performance 🏎️

• Flatten deep BooleanOr chains in TypeSpecifier to avoid O(n^2) recursion (#5324), thanks @SanderMuller!

Internals 🔍

• More named arguments (phpstan/phpstan-src@38036bf)
• Simplify StubValidator rule list, introduce #[ValidatesStubFiles] attribute (phpstan/phpstan-src@b9839ac)
• StubValidator - call StubFilesProvider on the original DIC, not on the stubValidator one (phpstan/phpstan-src@47f36d8)
• Added regression test (#5306), FP of generic inference when constructing an empty set datastructure and assigning with ??= #10924, thanks @staabm!
• Added regression test (#5313), Integer value analysis can be broken by passing variable as reference to a callback #4918, thanks @staabm!