feat(linter): init note field boilerplate

Cargo.toml

@@ -201,7 +201,7 @@ lazy-regex = "3.4.2" # Lazy regex compilation
 log = "0.4.29" # Logging facade
 markdown = "1.0.0" # Markdown parsing
 memchr = "2.7.6" # Fast byte searching
-miette = { package = "oxc-miette", version = "2.6.0", features = [
+miette = { package = "oxc-miette", version = "2.7.0", features = [
   "fancy-no-syscall",
 ] } # Error reporting
 mimalloc-safe = "0.1.55" # Fast allocator

crates/oxc_diagnostics/src/lib.rs

@@ -119,6 +119,7 @@ pub struct OxcDiagnosticInner {
     pub message: Cow<'static, str>,
     pub labels: Option<Vec<LabeledSpan>>,
     pub help: Option<Cow<'static, str>>,
+    pub note: Option<Cow<'static, str>>,
     pub severity: Severity,
     pub code: OxcCode,
     pub url: Option<Cow<'static, str>>,
@@ -138,6 +139,14 @@ impl Diagnostic for OxcDiagnostic {
         self.help.as_ref().map(Box::new).map(|c| c as Box<dyn Display>)
     }
 
+    /// A note for the diagnostic.
+    ///
+    /// Similar to rustc - intended for additional explanation and information,
+    /// e.g. why an error was emitted, how to turn it off.
+    fn note<'a>(&'a self) -> Option<Box<dyn Display + 'a>> {
+        self.note.as_ref().map(Box::new).map(|c| c as Box<dyn Display>)
+    }
+
     /// The severity level of this diagnostic.
     ///
     /// Diagnostics with missing severity levels should be treated as [errors](Severity::Error).
@@ -174,6 +183,7 @@ impl OxcDiagnostic {
             inner: Box::new(OxcDiagnosticInner {
                 message: message.into(),
                 labels: None,
+                note: None,
                 help: None,
                 severity: Severity::Error,
                 code: OxcCode::default(),
@@ -189,6 +199,7 @@ impl OxcDiagnostic {
                 message: message.into(),
                 labels: None,
                 help: None,
+                note: None,
                 severity: Severity::Warning,
                 code: OxcCode::default(),
                 url: None,
@@ -269,6 +280,25 @@ impl OxcDiagnostic {
         self
     }
 
+    /// Show a note to the user.
+    ///
+    /// ## Example
+    /// ```
+    /// use std::path::PathBuf;
+    /// use oxc_diagnostics::OxcDiagnostic
+    ///
+    /// let config_file_path = Path::from("config.json");
+    /// if !config_file_path.exists() {
+    ///     return Err(OxcDiagnostic::error("No config file found")
+    ///         .with_help("Run my_tool --init to set up a new config file")
+    ///         .with_note("Some useful information or suggestion"));
+    /// }
+    /// ```
+    pub fn with_note<T: Into<Cow<'static, str>>>(mut self, note: T) -> Self {
+        self.inner.note = Some(note.into());
+        self
+    }
+
     /// Set the label covering a problematic portion of source code.
     ///
     /// Existing labels will be removed. Use [`OxcDiagnostic::and_label`] append a label instead.

crates/oxc_linter/src/rules/oxc/no_accumulating_spread.rs

@@ -19,7 +19,8 @@ use crate::{
 
 fn reduce_likely_array_spread_diagnostic(spread_span: Span, reduce_span: Span) -> OxcDiagnostic {
     OxcDiagnostic::warn("Do not spread accumulators in Array.prototype.reduce()")
-        .with_help("It looks like you're spreading an `Array`. Consider using the `Array.push` or `Array.concat` methods to mutate the accumulator instead.\nUsing spreads within accumulators leads to `O(n^2)` time complexity.")
+        .with_help("It looks like you're spreading an `Array`. Consider using the `Array.push` or `Array.concat` methods to mutate the accumulator instead.")
+        .with_note("Using spreads within accumulators leads to `O(n^2)` time complexity.")
         .with_labels([
             spread_span.label("From this spread"),
             reduce_span.label("For this reduce")
@@ -28,7 +29,8 @@ fn reduce_likely_array_spread_diagnostic(spread_span: Span, reduce_span: Span) -
 
 fn reduce_likely_object_spread_diagnostic(spread_span: Span, reduce_span: Span) -> OxcDiagnostic {
     OxcDiagnostic::warn("Do not spread accumulators in Array.prototype.reduce()")
-        .with_help("It looks like you're spreading an `Object`. Consider using the `Object.assign` or assignment operators to mutate the accumulator instead.\nUsing spreads within accumulators leads to `O(n^2)` time complexity.")
+        .with_help("It looks like you're spreading an `Object`. Consider using the `Object.assign` or assignment operators to mutate the accumulator instead.")
+        .with_note("Using spreads within accumulators leads to `O(n^2)` time complexity.")
         .with_labels([
             spread_span.label("From this spread"),
             reduce_span.label("For this reduce")
@@ -37,7 +39,8 @@ fn reduce_likely_object_spread_diagnostic(spread_span: Span, reduce_span: Span)
 
 fn reduce_unknown(spread_span: Span, reduce_span: Span) -> OxcDiagnostic {
     OxcDiagnostic::warn("Do not spread accumulators in Array.prototype.reduce()")
-        .with_help("Consider using `Object.assign()` or `Array.prototype.push()` to mutate the accumulator instead.\nUsing spreads within accumulators leads to `O(n^2)` time complexity.")
+        .with_help("Consider using `Object.assign()` or `Array.prototype.push()` to mutate the accumulator instead.")
+        .with_note("Using spreads within accumulators leads to `O(n^2)` time complexity.")
         .with_labels([
             spread_span.label("From this spread"),
             reduce_span.label("For this reduce")
@@ -50,11 +53,12 @@ fn loop_spread_likely_object_diagnostic(
     loop_span: Span,
 ) -> OxcDiagnostic {
     OxcDiagnostic::warn("Do not spread accumulators in loops")
-        .with_help("Consider using `Object.assign()` to mutate the accumulator instead.\nUsing spreads within accumulators leads to `O(n^2)` time complexity.")
+        .with_help("Consider using `Object.assign()` to mutate the accumulator instead.")
+        .with_note("Using spreads within accumulators leads to `O(n^2)` time complexity.")
         .with_labels([
             accumulator_decl_span.label("From this accumulator"),
             spread_span.label("From this spread"),
-            loop_span.label("For this loop")
+            loop_span.label("For this loop"),
         ])
 }
 fn loop_spread_likely_array_diagnostic(
@@ -63,11 +67,12 @@ fn loop_spread_likely_array_diagnostic(
     loop_span: Span,
 ) -> OxcDiagnostic {
     OxcDiagnostic::warn("Do not spread accumulators in loops")
-        .with_help("Consider using `Array.prototype.push()` to mutate the accumulator instead.\nUsing spreads within accumulators leads to `O(n^2)` time complexity.")
+        .with_help("Consider using `Array.prototype.push()` to mutate the accumulator instead.")
+        .with_note("Using spreads within accumulators leads to `O(n^2)` time complexity.")
         .with_labels([
             accumulator_decl_span.label("From this accumulator"),
             spread_span.label("From this spread"),
-            loop_span.label("For this loop")
+            loop_span.label("For this loop"),
         ])
 }