Use `ast.unparse` for generating patches with `lib_updater.py` by ShaharNaveh · Pull Request #6142 · RustPython/RustPython

sequenceDiagram
    actor Dev as Developer/CLI
    participant LU as LibUpdater
    participant AST as Python AST
    participant SF as Source File
    participant JSON as Patches JSON

    rect rgb(235, 245, 255)
    note right of LU: Phase 1/2 Patch Emission (AST-driven)
    Dev->>LU: run update
    LU->>AST: build decorator nodes (PatchSpec.as_ast_node)
    AST-->>LU: ast.Attribute / ast.Call
    LU->>LU: render as_decorator() and indent with DEFAULT_INDENT
    LU->>SF: write decorators and wrappers
    end

    rect rgb(245, 235, 255)
    note right of LU: Patch Extraction (reason/cond)
    LU->>AST: parse source for UT methods
    alt UT method has_args()
        LU->>AST: walk dec_node for COMMENT string and optional cond
        AST-->>LU: reason, cond
    else No args
        LU->>SF: scan surrounding lines for COMMENT
        SF-->>LU: reason line
    end
    LU->>LU: normalize reason via removeprefix(COMMENT)
    end

    rect rgb(235, 255, 240)
    note right of LU: JSON I/O
    LU->>JSON: load patches
    JSON-->>LU: dicts
    LU->>LU: convert ut_method -> UtMethod via _replace
    LU-->>Dev: show-patches via spec._asdict()
    end