Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::seek_from_current: using `SeekFrom::Current` to start from current position

What it meansChecks if the seek method of the Seek trait is called with SeekFrom::Current(0), and if it is, suggests using stream_position instead. It is in the complexity group and warns by default.

What you see

warning: using `SeekFrom::Current` to start from current position
 --> main.rs:7:35
  |
7 |     eprintln!("Written {} bytes", f.seek(SeekFrom::Current(0))?);
  |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `f.stream_position()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#seek_from_current
  = note: `#[warn(clippy::seek_from_current)]` on by default

Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.

Does it matter?

Readability. Use dedicated method.

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.

Flagged

use std::fs::File;
use std::io::{self, Write, Seek, SeekFrom};

fn main() -> io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello")?;
    eprintln!("Written {} bytes", f.seek(SeekFrom::Current(0))?);

    Ok(())
}

Write this instead

use std::fs::File;
use std::io::{self, Write, Seek, SeekFrom};

fn main() -> io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello")?;
    eprintln!("Written {} bytes", f.stream_position()?);

    Ok(())
}

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::seek_from_current)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
seek_from_current = "allow"

One run

cargo clippy -- -A clippy::seek-from-current

The [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.

Settings in clippy.toml

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.67.0added in Rust

Clippy's own documentation

What it does

Checks if the seek method of the Seek trait is called with SeekFrom::Current(0), and if it is, suggests using stream_position instead.

Why is this bad?

Readability. Use dedicated method.

Example

use std::fs::File;
use std::io::{self, Write, Seek, SeekFrom};

fn main() -> io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello")?;
    eprintln!("Written {} bytes", f.seek(SeekFrom::Current(0))?);

    Ok(())
}

Use instead:

use std::fs::File;
use std::io::{self, Write, Seek, SeekFrom};

fn main() -> io::Result<()> {
    let mut f = File::create("foo.txt")?;
    f.write_all(b"Hello")?;
    eprintln!("Written {} bytes", f.stream_position()?);

    Ok(())
}

Configuration

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

(default: current version)

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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