Didin't touch Coalesce in this PR, because going to fix in separate PR #1104

Tests are not skipped in old PHP versions 🤔

solved

Sorry, I can't wrap my head around the fact there are two PRs for the same issue: #1104 + #1105 Can you please explain what's your intention here before I review?

@ondrejmirtes

#1104 is only for Coalesce now, and for solving other issues. I cherry picked the first two commits to this PR (which fixes phpstan/phpstan#6870, the scope for BinaryOp except Coalesce).

As https://phpstan.org/r/9ad910e5-7783-4441-9cb6-98548cce54eb shows, Coalesce is already working with this case because of #1063, but the scope is not precise enough like phpstan/phpstan#4885 is not solved.

I thought that Coalesce expr

$leftExpr ?? $rightExpr

process can be replaced by simulating isset Ternary

isset($leftExpr) ? $leftExpr : $rightExpr

which handles the scope problem perfectly (fixes phpstan/phpstan#4885), and also fixes a lot of issues like phpstan/phpstan#6026, issues caused from difference between the implementation of Coalesce and Isset_.
There are still several problems to fix with #1104, but the fact that phpstan/phpstan#6870 can be solved without fixing Coalesce, I separated into two PRs.

Alright, thank you!