Zero-cost asynchronous programming in Rust
This report presents the forensic synthetic code analysis of rust-lang/futures-rs, a Rust project with 5,909 GitHub stars. SynthScan v2.0 examined 47,740 lines of code across 338 source files, recording 484 pattern matches distributed across 4 syntactic categories. The overall adjusted score of 9.4 places this repository in the Low AI signal band.
The scanner applied 160+ deterministic lexical heuristics, multi-line block detectors, abstract syntax tree depth profilers, and a cross-file Jaccard similarity matrix to construct a statistically normalised synthetic code estimate. All matches are individually weighted by severity coefficient and contextual multiplier before summation, and the resulting headline score is temporally discounted to account for the repository's development history relative to the commercial emergence of large language model coding tooling (November 2022 onward).
This chart maps the temporal evolution of the adjusted synthetic code score across successive scan runs. An upward trajectory indicates ongoing incorporation of AI-generated code or expanding LLM-assisted scaffolding; a stable or declining trajectory may reflect active human refactoring, code removal, or the adoption of stricter authorship policies. The dashed secondary line (right axis) independently tracks total raw pattern hit count, which can diverge from the normalised score when codebase size changes significantly between scans.
Classifies detected patterns by their diagnostic confidence and structural impact. CRITICAL patterns (coefficient 10) represent definitive synthetic signatures — hallucinated imports, explicit LLM attribution metadata — virtually never produced by human authors. HIGH (5) indicates strong structural tells such as cross-file repetition or cross-linguistic idioms. MEDIUM (2) covers recognisable conversational padding and AI-specific vocabulary. LOW (1) captures subtle indicators like tautological comments and generic boilerplate that require density to carry independent signal.
This horizontal bar chart decomposes the repository's raw synthetic code score by top-level directory, allowing you to pinpoint precisely which modules or components carry the highest AI authorship density. Directories with disproportionately high scores relative to their size warrant targeted manual review: concentrated AI signatures often trace back to mass-generated configuration layers, auto-ported test suites, LLM-scaffolded boilerplate classes, or entire subsystems authored under heavy copilot assistance. Use this view to prioritise your human code-review effort.
The scanner identified 484 distinct pattern matches across 4 syntactic categories. Each entry below represents a discrete location in the source code where the engine recorded a statistically significant AI authorship indicator. Expand any category row to inspect the individual file paths, line numbers, code snippets, and the lexical context (CODE, COMMENT, or STRING) in which each match was detected.
Reading the findings table: The Severity column indicates the diagnostic confidence level (CRITICAL / HIGH / MEDIUM / LOW). The Context column identifies whether the match occurred inside executable code, an inline comment, or a string literal — comment-context matches receive a ×1.5 weight because LLMs systematically over-annotate. The ⚡ bolt icon marks clustered matches: three or more patterns within a 10-line window, each receiving an additional ×1.5 density multiplier as dense clusters constitute far stronger evidence of synthetic authorship than isolated hits.
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | futures-task/src/waker_ref.rs | 21 | impl<'a> WakerRef<'a> { | COMMENT |
| LOW | futures-task/src/future_obj.rs | 121 | impl<T> Future for FutureObj<'_, T> { | COMMENT |
| LOW | futures-task/src/future_obj.rs | 141 | /// Convert an owned instance into a (conceptually owned) fat pointer. | COMMENT |
| LOW | futures-task/src/lib.rs | 21 | #[cfg(target_has_atomic = "ptr")] | COMMENT |
| LOW | futures-task/src/noop_waker.rs | 21 | /// Create a new [`Waker`] which does | COMMENT |
| LOW | futures-task/src/spawn.rs | 1 | use core::fmt; | COMMENT |
| LOW | futures-task/src/spawn.rs | 21 | /// (but not guaranteed) to accept a subsequent spawn attempt. | COMMENT |
| LOW | futures-task/src/arc_wake.rs | 1 | use alloc::sync::Arc; | COMMENT |
| LOW | futures-task/src/arc_wake.rs | 21 | /// Indicates that the associated task is ready to make progress and should | COMMENT |
| LOW | futures-task/src/arc_wake.rs | 41 | /// Executors generally maintain a queue of "ready" tasks; `wake_by_ref` should place | COMMENT |
| LOW | futures/tests/no-std/src/lib.rs | 1 | #![cfg(nightly)] | COMMENT |
| LOW | futures/src/lib.rs | 1 | //! Abstractions for asynchronous programming. | COMMENT |
| LOW | futures/src/lib.rs | 21 | //! streams and sinks, and then spawned as independent tasks that are run to | COMMENT |
| LOW | futures/src/lib.rs | 41 | //! let fut_values = async { | COMMENT |
| LOW | futures/src/lib.rs | 61 | //! let fut_values = rx | COMMENT |
| LOW | futures/src/lib.rs | 101 | #[doc(inline)] | COMMENT |
| LOW | futures/src/lib.rs | 121 | pub use futures_util::lock; | COMMENT |
| LOW | futures/src/lib.rs | 141 | #[cfg(feature = "executor")] | COMMENT |
| LOW | futures/src/lib.rs | 161 | //! | COMMENT |
| LOW | futures/src/lib.rs | 181 | //! [`spawn_local_obj`]: https://docs.rs/futures/0.3/futures/task/trait.LocalSpawn.html#tymethod.spawn_local_obj | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 121 | orx.close(); | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 141 | // use futures::future::Either; | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 161 | // } | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 181 | // // end. | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 201 | // use std::thread; | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 221 | // Ok(Poll::Pending) | COMMENT |
| LOW | futures-channel/tests/oneshot.rs | 241 | // // forget the spawned future: should keep running, i.e. hit | COMMENT |
| LOW | futures-channel/tests/mpsc.rs | 141 | })); | COMMENT |
| LOW | futures-channel/tests/mpsc.rs | 161 | // // responding), but dropping it leads to observable side effects | COMMENT |
| LOW | futures-channel/tests/mpsc.rs | 181 | // thread::spawn(move || { | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 41 | /// Indicates whether this oneshot is complete yet. This is filled in both | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 61 | /// Field to store the task which is blocked in `Receiver::poll`. | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 81 | /// half is a `Receiver` which implements the `Future` trait, resolving to the | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 161 | // destructor, but our destructor hasn't run yet so if it's set then the | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 201 | // 2. The receiver is being dropped | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 301 | // Indicate to the `Sender` that we're done, so any future calls to | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 341 | pub fn send(self, t: T) -> Result<(), T> { | COMMENT |
| LOW | futures-channel/src/oneshot.rs | 361 | /// Creates a future that resolves when this `Sender`'s corresponding | COMMENT |
| LOW | futures-channel/src/lib.rs | 1 | //! Asynchronous channels. | COMMENT |
| LOW | futures-channel/src/mpsc/queue.rs | 21 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | COMMENT |
| LOW | futures-channel/src/mpsc/queue.rs | 101 | let prev = self.head.swap(n, Ordering::AcqRel); | COMMENT |
| LOW | futures-channel/src/mpsc/queue.rs | 141 | loop { | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 1 | //! A multi-producer, single-consumer queue for sending values across | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 21 | //! | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 41 | // At the core, the channel uses an atomic FIFO queue for message passing. This | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 61 | // message that caused the sender to become parked is read out of the channel. | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 1021 | // Wake up any threads waiting as they'll see that we've closed the | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 1241 | /// It is not recommended to call this function from inside of a future, | COMMENT |
| LOW | futures-executor/src/thread_pool.rs | 21 | /// A general-purpose thread pool for scheduling tasks that poll futures to | COMMENT |
| LOW | futures-executor/src/thread_pool.rs | 81 | impl ThreadPool { | COMMENT |
| LOW | futures-executor/src/thread_pool.rs | 101 | /// > it is guaranteed to always succeed. | COMMENT |
| LOW | futures-executor/src/thread_pool.rs | 221 | /// Thread name prefix is used for generating thread names. For example, if prefix is | COMMENT |
| LOW | futures-executor/src/lib.rs | 1 | //! Built-in executors and related tools. | COMMENT |
| LOW | futures-executor/src/lib.rs | 21 | //! directly. In the case of `!Send` futures, [`spawn_local_obj`] can be used | COMMENT |
| LOW | futures-executor/src/lib.rs | 61 | #[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))] | COMMENT |
| LOW | futures-executor/src/unpark_mutex.rs | 21 | // re-polling. | COMMENT |
| LOW | futures-executor/src/enter.rs | 41 | /// | COMMENT |
| LOW | futures-executor/src/local_pool.rs | 21 | COMMENT | |
| LOW | futures-executor/src/local_pool.rs | 121 | LocalSpawner { incoming: Rc::downgrade(&self.incoming) } | COMMENT |
| LOW | futures-executor/src/local_pool.rs | 141 | } | COMMENT |
| 418 more matches not shown… | ||||
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | futures/tests/async_await_macros.rs | 348 | // This test may be a bit flaky. Feel free to adjust the margins as you see fit. | COMMENT |
| MEDIUM | futures-core/src/task/__internal/atomic_waker.rs | 40 | /// Here is a simple example providing a `Flag` that can be signalled manually | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| LOW | futures-channel/src/mpsc/mod.rs | 640 | /// # Return value | COMMENT |
| LOW | futures-channel/src/mpsc/mod.rs | 740 | /// # Return value | COMMENT |
| LOW | futures-core/src/stream.rs | 47 | /// # Return value | COMMENT |
| Severity | File | Line | Snippet | Context |
|---|---|---|---|---|
| MEDIUM | futures-util/src/io/line_writer.rs | 19 | /// Buffering is actually done using `BufWriter`. This class will leverage `BufWriter` | COMMENT |