206 lines
6.3 KiB
Rust
206 lines
6.3 KiB
Rust
//! Clippy wrappers around rustc's diagnostic functions.
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use rustc::hir::HirId;
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use rustc::lint::{LateContext, Lint, LintContext};
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use rustc_errors::{Applicability, CodeSuggestion, Substitution, SubstitutionPart, SuggestionStyle};
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use std::env;
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use syntax::errors::DiagnosticBuilder;
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use syntax::source_map::{MultiSpan, Span};
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/// Wrapper around `DiagnosticBuilder` that adds a link to Clippy documentation for the emitted lint
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struct DiagnosticWrapper<'a>(DiagnosticBuilder<'a>);
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impl<'a> Drop for DiagnosticWrapper<'a> {
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fn drop(&mut self) {
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self.0.emit();
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}
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}
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impl<'a> DiagnosticWrapper<'a> {
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fn docs_link(&mut self, lint: &'static Lint) {
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if env::var("CLIPPY_DISABLE_DOCS_LINKS").is_err() {
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self.0.help(&format!(
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"for further information visit https://rust-lang.github.io/rust-clippy/{}/index.html#{}",
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&option_env!("RUST_RELEASE_NUM").map_or("master".to_string(), |n| {
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// extract just major + minor version and ignore patch versions
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format!("rust-{}", n.rsplitn(2, '.').nth(1).unwrap())
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}),
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lint.name_lower().replacen("clippy::", "", 1)
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));
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}
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}
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}
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/// Emit a basic lint message with a `msg` and a `span`.
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///
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/// This is the most primitive of our lint emission methods and can
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/// be a good way to get a new lint started.
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///
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/// Usually it's nicer to provide more context for lint messages.
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/// Be sure the output is understandable when you use this method.
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///
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/// # Example
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///
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/// ```ignore
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/// error: usage of mem::forget on Drop type
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/// --> $DIR/mem_forget.rs:17:5
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/// |
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/// 17 | std::mem::forget(seven);
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/// | ^^^^^^^^^^^^^^^^^^^^^^^
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/// ```
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pub fn span_lint<'a, T: LintContext<'a>>(cx: &T, lint: &'static Lint, sp: impl Into<MultiSpan>, msg: &str) {
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DiagnosticWrapper(cx.struct_span_lint(lint, sp, msg)).docs_link(lint);
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}
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/// Same as `span_lint` but with an extra `help` message.
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///
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/// Use this if you want to provide some general help but
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/// can't provide a specific machine applicable suggestion.
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///
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/// The `help` message is not attached to any `Span`.
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///
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/// # Example
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///
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/// ```ignore
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/// error: constant division of 0.0 with 0.0 will always result in NaN
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/// --> $DIR/zero_div_zero.rs:6:25
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/// |
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/// 6 | let other_f64_nan = 0.0f64 / 0.0;
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/// | ^^^^^^^^^^^^
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/// |
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/// = help: Consider using `std::f64::NAN` if you would like a constant representing NaN
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/// ```
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pub fn span_help_and_lint<'a, 'tcx: 'a, T: LintContext<'tcx>>(
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cx: &'a T,
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lint: &'static Lint,
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span: Span,
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msg: &str,
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help: &str,
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) {
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let mut db = DiagnosticWrapper(cx.struct_span_lint(lint, span, msg));
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db.0.help(help);
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db.docs_link(lint);
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}
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/// Like `span_lint` but with a `note` section instead of a `help` message.
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///
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/// The `note` message is presented separately from the main lint message
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/// and is attached to a specific span:
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///
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/// # Example
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///
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/// ```ignore
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/// error: calls to `std::mem::forget` with a reference instead of an owned value. Forgetting a reference does nothing.
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/// --> $DIR/drop_forget_ref.rs:10:5
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/// |
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/// 10 | forget(&SomeStruct);
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/// | ^^^^^^^^^^^^^^^^^^^
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/// |
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/// = note: `-D clippy::forget-ref` implied by `-D warnings`
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/// note: argument has type &SomeStruct
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/// --> $DIR/drop_forget_ref.rs:10:12
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/// |
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/// 10 | forget(&SomeStruct);
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/// | ^^^^^^^^^^^
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/// ```
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pub fn span_note_and_lint<'a, 'tcx: 'a, T: LintContext<'tcx>>(
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cx: &'a T,
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lint: &'static Lint,
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span: Span,
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msg: &str,
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note_span: Span,
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note: &str,
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) {
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let mut db = DiagnosticWrapper(cx.struct_span_lint(lint, span, msg));
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if note_span == span {
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db.0.note(note);
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} else {
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db.0.span_note(note_span, note);
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}
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db.docs_link(lint);
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}
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pub fn span_lint_and_then<'a, 'tcx: 'a, T: LintContext<'tcx>, F>(
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cx: &'a T,
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lint: &'static Lint,
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sp: Span,
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msg: &str,
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f: F,
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) where
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F: for<'b> FnOnce(&mut DiagnosticBuilder<'b>),
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{
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let mut db = DiagnosticWrapper(cx.struct_span_lint(lint, sp, msg));
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f(&mut db.0);
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db.docs_link(lint);
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}
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pub fn span_lint_hir(cx: &LateContext<'_, '_>, lint: &'static Lint, hir_id: HirId, sp: Span, msg: &str) {
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DiagnosticWrapper(cx.tcx.struct_span_lint_hir(lint, hir_id, sp, msg)).docs_link(lint);
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}
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pub fn span_lint_hir_and_then(
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cx: &LateContext<'_, '_>,
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lint: &'static Lint,
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hir_id: HirId,
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sp: Span,
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msg: &str,
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f: impl FnOnce(&mut DiagnosticBuilder<'_>),
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) {
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let mut db = DiagnosticWrapper(cx.tcx.struct_span_lint_hir(lint, hir_id, sp, msg));
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f(&mut db.0);
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db.docs_link(lint);
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}
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/// Add a span lint with a suggestion on how to fix it.
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///
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/// These suggestions can be parsed by rustfix to allow it to automatically fix your code.
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/// In the example below, `help` is `"try"` and `sugg` is the suggested replacement `".any(|x| x >
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/// 2)"`.
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///
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/// ```ignore
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/// error: This `.fold` can be more succinctly expressed as `.any`
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/// --> $DIR/methods.rs:390:13
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/// |
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/// 390 | let _ = (0..3).fold(false, |acc, x| acc || x > 2);
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/// | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `.any(|x| x > 2)`
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/// |
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/// = note: `-D fold-any` implied by `-D warnings`
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/// ```
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pub fn span_lint_and_sugg<'a, 'tcx: 'a, T: LintContext<'tcx>>(
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cx: &'a T,
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lint: &'static Lint,
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sp: Span,
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msg: &str,
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help: &str,
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sugg: String,
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applicability: Applicability,
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) {
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span_lint_and_then(cx, lint, sp, msg, |db| {
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db.span_suggestion(sp, help, sugg, applicability);
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});
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}
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/// Create a suggestion made from several `span → replacement`.
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///
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/// Note: in the JSON format (used by `compiletest_rs`), the help message will
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/// appear once per
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/// replacement. In human-readable format though, it only appears once before
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/// the whole suggestion.
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pub fn multispan_sugg<I>(db: &mut DiagnosticBuilder<'_>, help_msg: String, sugg: I)
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where
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I: IntoIterator<Item = (Span, String)>,
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{
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let sugg = CodeSuggestion {
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substitutions: vec![Substitution {
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parts: sugg
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.into_iter()
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.map(|(span, snippet)| SubstitutionPart { snippet, span })
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.collect(),
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}],
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msg: help_msg,
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style: SuggestionStyle::ShowCode,
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applicability: Applicability::Unspecified,
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};
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db.suggestions.push(sugg);
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}
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