Add change note for instance-attribute type-tracking performance fix

Copilot · owen-mc · commit 7acbbb7c1b4f · 2026-07-02T14:18:53.000+01:00
diff --git a/python/ql/lib/change-notes/2026-06-30-instance-attribute-typetracking-performance.md b/python/ql/lib/change-notes/2026-06-30-instance-attribute-typetracking-performance.md
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+---
+category: minorAnalysis
+---
+* Type tracking of values stored in instance attributes and read from outside the class (for example `instance.attr` where the value was assigned to `self.attr` in a method) no longer relies on a dedicated instance type-tracker. This avoids a structural mutual recursion that could cause catastrophic query slowdowns on some OOP-heavy code bases. Such reads are now resolved using local flow from the constructor call, which is slightly less precise for instances that flow across a call or return before being read.

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 +---
 +category: minorAnalysis
 +---
 +* Type tracking of values stored in instance attributes and read from outside the class (for example `instance.attr` where the value was assigned to `self.attr` in a method) no longer relies on a dedicated instance type-tracker. This avoids a structural mutual recursion that could cause catastrophic query slowdowns on some OOP-heavy code bases. Such reads are now resolved using local flow from the constructor call, which is slightly less precise for instances that flow across a call or return before being read.