Rust errors / Types and traits
Rust compiler error · checked with rustc 1.99.0
Rust error E0689: can't call method `neg` on ambiguous numeric type `{float}`
What it meansA method was called on an ambiguous numeric type.
What rustc prints
error[E0689]: can't call method `neg` on ambiguous numeric type `{float}` --> main.rs:3:5 | 3 | 2.0.neg(); // error! | ^^^ | help: you must specify a concrete type for this numeric value, like `f32` | 3 | 2.0_f32.neg(); // error! | ++++
Real output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.
The compiler team's explanation
A method was called on an ambiguous numeric type.
Erroneous code example:
2.0.neg(); // error!This error indicates that the numeric value for the method being passed exists but the type of the numeric value or binding could not be identified.
The error happens on numeric literals and on numeric bindings without an identified concrete type:
let x = 2.0;
x.neg(); // same error as aboveBecause of this, you must give the numeric literal or binding a type:
use std::ops::Neg;
let _ = 2.0_f32.neg(); // ok!
let x: f32 = 2.0;
let _ = x.neg(); // ok!
let _ = (2.0 as f32).neg(); // ok!From rustc --explain E0689 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
Related errors
- E0308mismatched types
- E0277the trait bound is not satisfied
- E0599no method named X found in the current scope
- E0433failed to resolve
- E0665`#[derive(Default)]` on enum with no `#[default]`
- E0666nested `impl Trait` is not allowed
- E0690transparent struct needs at most one non-trivial field, but has 2
- E0692transparent struct cannot have other repr hints
Up next
Often hit nextE0308: mismatched typesA related error from the same family.Read it next →Did this answer your question?