AST

Compare Python Syntax Trees with ast.compare

Tools that rewrite Python source often need to answer a deceptively simple question: did this transformation preserve the syntax tree that matters? Before Python 3.14, a common solution was to serialize both trees with ast.dump() and compare the resulting strings. That works in small tests, but it turns a structural question into a formatting contract. Python 3.14 adds ast.compare(), a recursive AST comparison helper that expresses the intent directly. This is especially useful for formatters, codemods, linters, source generators, refactoring tools, and tests that round-trip Python code.