rust type_error ai_generated true

error[E0282]: type annotations needed

ID: rust/e0282-type-annotations-needed

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95%Fix Rate
95%Confidence
50Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1 active — — —

Root Cause

Rust can't infer the type. Need explicit annotation or turbofish syntax.

generic

Workarounds

  1. 95% success Add type annotation: let x: Vec<i32> = vec![]; 
    let x: Vec<i32> = vec![];

    Sources: https://doc.rust-lang.org/error_codes/E0282.html

  2. 92% success Use turbofish syntax: iter.collect::<Vec<_>>() 
    iter.collect::<Vec<_>>()

    Sources: https://doc.rust-lang.org/reference/expressions/method-call-expr.html

  3. 85% success Provide type through usage context: the compiler can sometimes infer from how the value is used 
    the compiler can sometimes infer from how the value is used

    Sources: https://doc.rust-lang.org/book/ch03-02-data-types.html

Dead Ends

Common approaches that don't work:

  1. Use dyn Any to avoid specifying types 85% fail

    Loses all type safety — defeats the purpose of Rust's type system

  2. Use macro magic to auto-infer 80% fail

    Macros can't infer types that the compiler can't

Error Chain

Leads to:
Frequently confused with: