1 //! Clippy wrappers around rustc's diagnostic functions.
3 use rustc_errors::{Applicability, DiagnosticBuilder};
5 use rustc_lint::{LateContext, Lint, LintContext};
6 use rustc_span::source_map::{MultiSpan, Span};
9 fn docs_link(diag: &mut DiagnosticBuilder<'_>, lint: &'static Lint) {
10 if env::var("CLIPPY_DISABLE_DOCS_LINKS").is_err() {
11 if let Some(lint) = lint.name_lower().strip_prefix("clippy::") {
13 "for further information visit https://rust-lang.github.io/rust-clippy/{}/index.html#{}",
14 &option_env!("RUST_RELEASE_NUM").map_or("master".to_string(), |n| {
15 // extract just major + minor version and ignore patch versions
16 format!("rust-{}", n.rsplitn(2, '.').nth(1).unwrap())
24 /// Emit a basic lint message with a `msg` and a `span`.
26 /// This is the most primitive of our lint emission methods and can
27 /// be a good way to get a new lint started.
29 /// Usually it's nicer to provide more context for lint messages.
30 /// Be sure the output is understandable when you use this method.
35 /// error: usage of mem::forget on Drop type
36 /// --> $DIR/mem_forget.rs:17:5
38 /// 17 | std::mem::forget(seven);
39 /// | ^^^^^^^^^^^^^^^^^^^^^^^
41 pub fn span_lint<T: LintContext>(cx: &T, lint: &'static Lint, sp: impl Into<MultiSpan>, msg: &str) {
42 cx.struct_span_lint(lint, sp, |diag| {
43 let mut diag = diag.build(msg);
44 docs_link(&mut diag, lint);
49 /// Same as `span_lint` but with an extra `help` message.
51 /// Use this if you want to provide some general help but
52 /// can't provide a specific machine applicable suggestion.
54 /// The `help` message can be optionally attached to a `Span`.
56 /// If you change the signature, remember to update the internal lint `CollapsibleCalls`
61 /// error: constant division of 0.0 with 0.0 will always result in NaN
62 /// --> $DIR/zero_div_zero.rs:6:25
64 /// 6 | let other_f64_nan = 0.0f64 / 0.0;
67 /// = help: Consider using `f64::NAN` if you would like a constant representing NaN
69 pub fn span_lint_and_help<'a, T: LintContext>(
74 help_span: Option<Span>,
77 cx.struct_span_lint(lint, span, |diag| {
78 let mut diag = diag.build(msg);
79 if let Some(help_span) = help_span {
80 diag.span_help(help_span, help);
84 docs_link(&mut diag, lint);
89 /// Like `span_lint` but with a `note` section instead of a `help` message.
91 /// The `note` message is presented separately from the main lint message
92 /// and is attached to a specific span:
94 /// If you change the signature, remember to update the internal lint `CollapsibleCalls`
99 /// error: calls to `std::mem::forget` with a reference instead of an owned value. Forgetting a reference does nothing.
100 /// --> $DIR/drop_forget_ref.rs:10:5
102 /// 10 | forget(&SomeStruct);
103 /// | ^^^^^^^^^^^^^^^^^^^
105 /// = note: `-D clippy::forget-ref` implied by `-D warnings`
106 /// note: argument has type &SomeStruct
107 /// --> $DIR/drop_forget_ref.rs:10:12
109 /// 10 | forget(&SomeStruct);
112 pub fn span_lint_and_note<'a, T: LintContext>(
115 span: impl Into<MultiSpan>,
117 note_span: Option<Span>,
120 cx.struct_span_lint(lint, span, |diag| {
121 let mut diag = diag.build(msg);
122 if let Some(note_span) = note_span {
123 diag.span_note(note_span, note);
127 docs_link(&mut diag, lint);
132 /// Like `span_lint` but allows to add notes, help and suggestions using a closure.
134 /// If you need to customize your lint output a lot, use this function.
135 /// If you change the signature, remember to update the internal lint `CollapsibleCalls`
136 pub fn span_lint_and_then<C, S, F>(cx: &C, lint: &'static Lint, sp: S, msg: &str, f: F)
140 F: FnOnce(&mut DiagnosticBuilder<'_>),
142 cx.struct_span_lint(lint, sp, |diag| {
143 let mut diag = diag.build(msg);
145 docs_link(&mut diag, lint);
150 pub fn span_lint_hir(cx: &LateContext<'_>, lint: &'static Lint, hir_id: HirId, sp: Span, msg: &str) {
151 cx.tcx.struct_span_lint_hir(lint, hir_id, sp, |diag| {
152 let mut diag = diag.build(msg);
153 docs_link(&mut diag, lint);
158 pub fn span_lint_hir_and_then(
159 cx: &LateContext<'_>,
164 f: impl FnOnce(&mut DiagnosticBuilder<'_>),
166 cx.tcx.struct_span_lint_hir(lint, hir_id, sp, |diag| {
167 let mut diag = diag.build(msg);
169 docs_link(&mut diag, lint);
174 /// Add a span lint with a suggestion on how to fix it.
176 /// These suggestions can be parsed by rustfix to allow it to automatically fix your code.
177 /// In the example below, `help` is `"try"` and `sugg` is the suggested replacement `".any(|x| x >
180 /// If you change the signature, remember to update the internal lint `CollapsibleCalls`
185 /// error: This `.fold` can be more succinctly expressed as `.any`
186 /// --> $DIR/methods.rs:390:13
188 /// 390 | let _ = (0..3).fold(false, |acc, x| acc || x > 2);
189 /// | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `.any(|x| x > 2)`
191 /// = note: `-D fold-any` implied by `-D warnings`
193 #[cfg_attr(feature = "internal-lints", allow(clippy::collapsible_span_lint_calls))]
194 pub fn span_lint_and_sugg<'a, T: LintContext>(
201 applicability: Applicability,
203 span_lint_and_then(cx, lint, sp, msg, |diag| {
204 diag.span_suggestion(sp, help, sugg, applicability);
208 /// Create a suggestion made from several `span → replacement`.
210 /// Note: in the JSON format (used by `compiletest_rs`), the help message will
212 /// replacement. In human-readable format though, it only appears once before
213 /// the whole suggestion.
214 pub fn multispan_sugg<I>(diag: &mut DiagnosticBuilder<'_>, help_msg: &str, sugg: I)
216 I: IntoIterator<Item = (Span, String)>,
218 multispan_sugg_with_applicability(diag, help_msg, Applicability::Unspecified, sugg)
221 pub fn multispan_sugg_with_applicability<I>(
222 diag: &mut DiagnosticBuilder<'_>,
224 applicability: Applicability,
227 I: IntoIterator<Item = (Span, String)>,
229 diag.multipart_suggestion(help_msg, sugg.into_iter().collect(), applicability);