Bug: 170752694

Clone this repo:
  1. 3fa0e2d Upgrade scopeguard to 1.2.0 am: 7289ba40bb by Jeff Vander Stoep · 9 weeks ago emu-34-2-dev main master
  2. 7289ba4 Upgrade scopeguard to 1.2.0 by Jeff Vander Stoep · 10 weeks ago emu-34-3-release
  3. eaa643c Migrate to cargo_embargo. am: 0e6f36886f am: 2bd254bd3a am: d1a6bbc559 by Andrew Walbran · 5 months ago
  4. 27aeb57 Migrate to cargo_embargo. am: 0e6f36886f am: 5097bb2594 am: f56b1fd10b by Andrew Walbran · 5 months ago
  5. d1a6bbc Migrate to cargo_embargo. am: 0e6f36886f am: 2bd254bd3a by Andrew Walbran · 5 months ago


Rust crate for a convenient RAII scope guard that will run a given closure when it goes out of scope, even if the code between panics (assuming unwinding panic).

The defer! macro and guard are no_std compatible (require only core), but the on unwinding / not on unwinding strategies require linking to std. By default, the use_std crate feature is enabled. Disable the default features for no_std support.

Please read the API documentation here.

Minimum supported Rust version: 1.20

build_status crates

How to use

extern crate scopeguard;

use scopeguard::guard;

fn f() {
    defer! {
        println!("Called at return or panic");

use std::fs::File;
use std::io::Write;

fn g() {
    let f = File::create("newfile.txt").unwrap();
    let mut file = guard(f, |f| {
        // write file at return or panic
        let _ = f.sync_all();
    // access the file through the scope guard itself
    file.write_all(b"test me\n").unwrap();

Recent Changes

  • 1.2.0

    • Use ManuallyDrop instead of mem::forget in into_inner. (by @willtunnels)
    • Warn if the guard is not assigned to a variable and is dropped immediately instead of at the scope's end. (by @sergey-v-galtsev)
  • 1.1.0

    • Change macros (defer!, defer_on_success! and defer_on_unwind!) to accept statements. (by @konsumlamm)
  • 1.0.0

    • Change the closure type from FnMut(&mut T) to FnOnce(T): Passing the inner value by value instead of a mutable reference is a breaking change, but allows the guard closure to consume it. (by @tormol)

    • Add defer_on_success!, guard_on_success() and OnSuccess strategy, which triggers when scope is exited without panic. It's the opposite to defer_on_unwind! / guard_on_unwind() / OnUnwind.

    • Add ScopeGuard::into_inner(), which “defuses” the guard and returns the guarded value. (by @tormol)

    • Implement Sync for guards with non-Sync closures.

    • Require Rust 1.20

  • 0.3.3

    • Use #[inline] on a few more functions by @stjepang (#14)
    • Add examples to crate documentation
  • 0.3.2

    • Add crate categories
  • 0.3.1

    • Add defer_on_unwind!, Strategy trait
    • Rename GuardScopeGuard
    • Add ScopeGuard::with_strategy.
    • ScopeGuard now implements Debug.
    • Require Rust 1.11
  • 0.2.0

    • Require Rust 1.6
    • Use no_std unconditionally
    • No other changes
  • 0.1.2

    • Add macro defer!