[TomasVotruba]

Replaces the 17-branch instanceof chain in PHPStanNodeScopeResolver (the guard that propagates scope to $node->expr) with property_exists($node, 'expr') plus 5 explicit exclusions.

Equivalence

A raw property_exists swap is NOT equivalent - it also matches Assign, AssignOp, AssignRef, ArrowFunction and Foreach_. The first three and Foreach_ have dedicated branches right below and must fall through to them; ArrowFunction->expr must not inherit the scope here.

Excluding those 5 makes it match the chain exactly. Verified against all 42 expr-bearing php-parser node classes (AssignOp is abstract and covers its 13 subclasses): the guarded predicate matches the same 25 node types the chain lists, no more, no less.

if (property_exists($node, 'expr')
    && $node->expr instanceof Expr
    && ! $node instanceof Assign
    && ! $node instanceof AssignOp
    && ! $node instanceof AssignRef
    && ! $node instanceof ArrowFunction
    && ! $node instanceof Foreach_
) {
    $node->expr->setAttribute(AttributeKey::SCOPE, $mutatingScope);
    return;
}

Speed

The bare property lookup is ~3.6x cheaper than the chain (~184 ns vs ~668 ns/call). The shipped guarded variant adds 5 instanceof back for the expr-bearing case, but the common path (non-expr nodes, the majority of visited nodes) short-circuits on the single property_exists miss instead of walking 17 instanceof.

Bench

bench/scope_expr_dispatch_bench.php prints the divergent set for the raw swap, confirms the guarded variant is identical to the chain, and the CPU ratio:

php bench/scope_expr_dispatch_bench.php

Full vendor/bin/phpunit green (4869 tests). property_exists is whitelisted for this one file in phpstan.neon.

[TomasVotruba]

Folded the bench into #8790 together with the NoLongInstanceofChainRule. Note: the property_exists($node, 'expr') swap commit on this branch was left out on purpose - it is not equivalent to the instanceof chain (it also matches Assign/AssignOp/AssignRef, which have dedicated processAssign handling, plus ArrowFunction and Foreach_), so it changes behavior.