Both of these define "fuzzy" datatypes, which are mostly evaluated at runtime.
Currently, much of regular use of these will cause useless errors, so define
the stubs so that they simply support any kind of use that could happen.
This specific distinction seems to be very important for Psalm, as `explode()` and
`lowercase-string` are used aggressively across the codebase.
Also, this change expands the baseline by a few entries, since some of the code locations
instide Psalm itself have un-checked list destructuring operations, as well as array
access calls on potentially undefined array keys produced by `explode()`, which were
previously just `list<string>`, and are now `array{0: string, 1?: string}`, which is
a bit more precise.
* in PHP 8.0, `ReflectionUnionType` is composed on `ReflectionNamedType`s
* in PHP 8.1, `ReflectionIntersectionType` is composed of `ReflectionNamedType`s
* in PHP 8.2, `ReflectionUnionType` is composed of `ReflectionIntersectionType|ReflectionNamedType`s
Slight variations for each PHP version.
As per local testing, this doesn't work yet.
## Local testing setup:
I did some digging to make sure that the stubs work as expected.
Here's what I did to validate this patch locally (since I don't think it can really be fully automated)
## Create a dummy file to verify used symbols
```php
<?php
namespace Testing;
/** @return \ReflectionClass<\stdClass> */
function getAClass(): \ReflectionClass { throw new \Exception('irrelevant'); }
function getAnUnionType(): \ReflectionUnionType { throw new \Exception('irrelevant'); }
function getAnIntersectionType(): \ReflectionIntersectionType { throw new \Exception('irrelevant'); }
// verifying that `getName()` is stubbed in all versions: this should always be a `class-string<\stdClass>`
$name = getAClass()->getName();
// union types should appear starting with PHP 8.0. Starting with PHP 8.2, they allow for intersections.
$unionTypes = getAnUnionType()->getTypes();
// intersection types should appear starting with PHP 8.1
$intersectionTypes = getAnIntersectionType()->getTypes();
$results = [$name, $unionTypes, $intersectionTypes];
/** @psalm-trace $results */ // tracing this will show us the differences between versions
return $results;
```
## Run the script against various `vimeo/psalm` versions
```sh
docker run --rm -ti -v $(pwd):/app -w /app php:7.4 ./psalm --php-version=7.4 --no-cache reflection-test.php | grep Trace
docker run --rm -ti -v $(pwd):/app -w /app php:8.0 ./psalm --php-version=8.0 --no-cache reflection-test.php | grep Trace
docker run --rm -ti -v $(pwd):/app -w /app php:8.1 ./psalm --php-version=8.1 --no-cache reflection-test.php | grep Trace
docker run --rm -ti -v $(pwd):/app -w /app php:8.2.0RC7-cli ./psalm --php-version=8.2 --no-cache reflection-test.php | grep Trace
```
## Evaluate output
```
❯ docker run --rm -ti -v $(pwd):/app -w /app php:7.4 ./psalm --php-version=7.4 --no-cache reflection-test.php | grep Trace
ERROR: Trace - reflection-test.php:20:1 - $results: list{class-string<stdClass>, mixed, mixed} (see https://psalm.dev/224)
❯ docker run --rm -ti -v $(pwd):/app -w /app php:8.0 ./psalm --php-version=8.0 --no-cache reflection-test.php | grep Trace
ERROR: Trace - reflection-test.php:20:1 - $results: list{class-string<stdClass>, non-empty-list<ReflectionNamedType>, mixed} (see https://psalm.dev/224)
❯ docker run --rm -ti -v $(pwd):/app -w /app php:8.1 ./psalm --php-version=8.1 --no-cache reflection-test.php | grep Trace
ERROR: Trace - reflection-test.php:20:1 - $results: list{class-string<stdClass>, non-empty-list<ReflectionNamedType>, non-empty-list<ReflectionNamedType>} (see https://psalm.dev/224)
psalm on feature/#8720-improve-types-and-purity-for-reflection-symbols [!?] via 🐘 v8.1.13 via ❄️ impure (nix-shell) took 4s
❯ docker run --rm -ti -v $(pwd):/app -w /app php:8.2.0RC7-cli ./psalm --php-version=8.2 --no-cache reflection-test.php | grep Trace
ERROR: Trace - reflection-test.php:20:1 - $results: list{class-string<stdClass>, non-empty-list<ReflectionNamedType>, non-empty-list<ReflectionNamedType>} (see https://psalm.dev/224)
```
