Clippy lints / Correctness
Clippy lint · Correctness · checked with Clippy 0.1.99
clippy::panicking_overflow_checks: Detects C-style underflow/overflow checks
What it meansDetects C-style underflow/overflow checks. It is in the correctness group and denied by default (the build fails).
Does it matter?
These checks will, by default, panic in debug builds rather than check whether the operation caused an overflow.
Code that is almost certainly wrong. Denied by default: the build fails until you fix it or allow it.
How to fix it
Clippy does not fix this one automatically. Change the code by hand:
Flagged
if a + b < a {
// handle overflow
}
Write this instead
if a.checked_add(b).is_none() {
// handle overflow
}
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::panicking_overflow_checks)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
panicking_overflow_checks = "allow"One run
cargo clippy -- -A clippy::panicking-overflow-checksThe [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.
Clippy's own documentation
What it does
Detects C-style underflow/overflow checks.
Why is this bad?
These checks will, by default, panic in debug builds rather than check whether the operation caused an overflow.
Example
if a + b < a {
// handle overflow
}
Use instead:
if a.checked_add(b).is_none() {
// handle overflow
}
Or:
if a.overflowing_add(b).1 {
// handle overflow
}
Past names
- overflow_check_conditional
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- not_unsafe_ptr_arg_derefthis public function might dereference a raw pointer but is not marked `unsafe`
- option_env_unwrapthis will panic at run-time if the environment variable doesn't exist at compile-time
- out_of_bounds_indexingindex is out of bounds
- panicking_unwrapChecks for calls of unwrap[_err]() that will always fail
- possible_missing_commapossibly missing a comma here
- read_line_without_trimcalling `.parse()` on a string without trimming the trailing newline character
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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Related lintclippy::not_unsafe_ptr_arg_derefthis public function might dereference a raw pointer but is not marked `unsafe`Read it next →Did this answer your question?