rust-clippy/clippy_lints/src/utils/diagnostics.rs

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