E0282: type annotations needed Rust Origin: Application & API OSI layer 7 · Application Last updated 5 Nov 2026

Rust: error[E0282]: type annotations needed for `Vec<_>` / consider giving `x` an explicit type

The compiler can't infer a type from the available information.

Exact message you may see error[E0282]: type annotations neededtype annotations needed for `Vec<_>`error[E0283]: type annotations needed cannot satisfy `_: FromStr`consider giving `x` an explicit typecannot infer type for type parameter `T`
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Seen on: Rust

Meaning

Add a type annotation (let v: Vec<i32> = Vec::new();), use turbofish ("5".parse::<i32>(), collect::<Vec<_>>()), or give the value a use that fixes the type. Common with collect(), parse(), Default::default(), into() and empty collections.

Common causes

  • collect() without a target type
  • parse() result unused/unspecified
  • Empty Vec::new() never used with a type
  • .into()/Default::default() ambiguous
  • Closure params uninferred

⚡ Quick fix

  1. let v: Vec<_> = iter.collect();
  2. s.parse::<u32>()
  3. Annotate the variable/closure parameter

Detailed fix by platform

Rust

  1. let n = "42".parse::<i32>()?;

How to diagnose

  1. Site — Where's the ambiguity?
  2. Fix — Turbofish/annotation?
  3. Use — Type fixed later?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Application & API. Errors that are often confused with or caused by this one (click to open):

Blocking waiting for file lock on package cache / build directory — Cargo: Blocking waiting for file lock on package cache / on build directory (Rust)Blocking waiting for …cargo: failed to get from registry (spurious network error) — Cargo: warning: spurious network error (2 tries remaining): [35] SSL connect error / error: failed to download from `https://index.crates.io/...` (Rust)cargo: failed to get …cargo: failed to select a version for the requirement — Cargo: error: failed to select a version for the requirement `serde = "^2.0"` — candidate versions found which didn't match: 1.0.197 (Rust)cargo: failed to sele…E0038: the trait cannot be made into an object — Rust: error[E0038]: the trait `Shape` cannot be made into an object (not dyn compatible) (Rust)E0038: the trait cann…E0271: type mismatch resolving associated type — Rust: error[E0271]: type mismatch resolving `<impl Iterator as Iterator>::Item == i32` (Rust)E0271: type mismatch …E0277: the trait bound is not satisfied — Rust: error[E0277]: the trait bound `Foo: Display` is not satisfied / `Rc<RefCell<T>>` cannot be sent between threads safely (Rust)E0277: the trait boun…E0308 — Rust: error[E0308]: mismatched types — expected `X`, found `Y` (Rust)E0308E0599: no method named found for type — Rust: error[E0599]: no method named `push_str` found for struct `Vec<String>` in the current scope (Rust)E0599: no method name…E0282: ty…

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