Struct Violation 

pub struct Violation {
    pub rule_id: Cow<'static, str>,
    pub lint_level: LintLevel,
    pub message: Cow<'static, str>,
    pub span: Span,
    pub help: Option<Cow<'static, str>>,
    pub fix: Option<Fix>,
    /* private fields */
}

A lint violation with its diagnostic information

Display Format

When displayed to the user, violations appear as:

file.nu:10:5
warn(rule_name)

  ⚠ [message]                  <- Short diagnostic message
   ╭─[10:5]
10 │ code here
   ·     ─┬─
   ·      ╰── [label text]     <- Message (or help if short)
   ╰────

  help: [help text]            <- Detailed explanation/rationale

  ℹ Available fix: [explanation] <- Fix explanation
  - old code
  + new code                   <- From replacements

Example

Violation::new("prefer_pipeline_input", "Use pipeline input", span)
    .with_help("Pipeline input enables better composability and streaming performance")
    .with_fix(Fix::with_explanation(
        format!("Use $in instead of ${}:\n  {}", param, transformed_code),
        vec![Replacement::new(def_span, transformed_code)]
    ))

Fields

rule_id: Cow<'static, str>

lint_level: LintLevel

message: Cow<'static, str>

Short message shown in the warning header Should be concise, typically < 80 chars Example: “Use pipeline input instead of parameter”

span: Span

Span in source code where the violation occurs

help: Option<Cow<'static, str>>

Optional detailed explanation shown in the “help:” section Use this to explain WHY the code should change or provide rationale Example: “Pipeline input enables better composability and streaming performance”

fix: Option<Fix>

Optional automated fix that can be applied

Implementations

impl Violation

pub fn new( rule_id: &'static str, message: impl Into<Cow<'static, str>>, span: Span, ) -> Self

Create a new violation

Arguments

• rule_id - The lint rule identifier (e.g., “prefer_pipeline_input”)
• message - Short diagnostic message shown in the warning header
• span - Location in source code where the violation occurs

pub fn with_help(self, help: impl Into<Cow<'static, str>>) -> Self

Add detailed help text explaining why this change should be made

This appears in the “help:” section of the diagnostic output.

Example

violation.with_help("Pipeline input enables better composability and streaming performance")

pub fn with_fix(self, fix: Fix) -> Self

Add an automated fix to this violation

Example

violation.with_fix(Fix::with_explanation(
    "Replace with pipeline input version",
    vec![Replacement::new(span, new_code)]
))

Trait Implementations

impl Clone for Violation

fn clone(&self) -> Violation

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Violation

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.