https://nalar.dev/tags/static-analysis/ Recent content in Static Analysis on Nalar Hugo en-us Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/compare-python-syntax-trees-with-ast-compare/ Wed, 09 Sep 2026 00:00:00 +0700 https://nalar.dev/compare-python-syntax-trees-with-ast-compare/ <p>Tools that rewrite Python source often need to answer a deceptively simple question: did this transformation preserve the syntax tree that matters?</p> <p>Before Python 3.14, a common solution was to serialize both trees with <code>ast.dump()</code> and compare the resulting strings. That works in small tests, but it turns a structural question into a formatting contract. Python 3.14 adds <code>ast.compare()</code>, a recursive AST comparison helper that expresses the intent directly.</p> <p>This is especially useful for formatters, codemods, linters, source generators, refactoring tools, and tests that round-trip Python code.</p>