Auto merge of #4963 - JohnTitor:unknown-clippy-lint, r=phansch

Suggest similar lint name on `unknown_clippy_lints`

Suggest a similar lint name with Levenshtein distance on `unknown_clippy_lints`.
And lowercase suggestion behavior is also changed.

changelog: Suggest similar lint name on `unknown_clippy_lints`

clippy_lints/src/attrs.rs

@@ -18,6 +18,7 @@ use rustc_session::declare_tool_lint;
 use semver::Version;
 use syntax::ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
 use syntax::source_map::Span;
+use syntax::util::lev_distance::find_best_match_for_name;
 use syntax_pos::symbol::Symbol;
 
 declare_clippy_lint! {
@@ -329,24 +330,30 @@ fn check_clippy_lint_names(cx: &LateContext<'_, '_>, items: &[NestedMetaItem]) {
                     lint.span(),
                     &format!("unknown clippy lint: clippy::{}", name),
                     |db| {
-                        if name.as_str().chars().any(char::is_uppercase) {
-                            let name_lower = name.as_str().to_lowercase();
-                            match lint_store.check_lint_name(
-                                &name_lower,
-                                Some(tool_name.name)
-                            ) {
-                                // FIXME: can we suggest similar lint names here?
-                                // https://github.com/rust-lang/rust/pull/56992
-                                CheckLintNameResult::NoLint(None) => (),
-                                _ => {
-                                    db.span_suggestion(
-                                        lint.span(),
-                                        "lowercase the lint name",
-                                        name_lower,
-                                        Applicability::MaybeIncorrect,
-                                    );
-                                }
-                            }
+                        let name_lower = name.as_str().to_lowercase();
+                        let symbols = lint_store.get_lints().iter().map(
+                            |l| Symbol::intern(&l.name_lower())
+                        ).collect::<Vec<_>>();
+                        let sugg = find_best_match_for_name(
+                            symbols.iter(),
+                            &format!("clippy::{}", name_lower),
+                            None,
+                        );
+                        if name.as_str().chars().any(char::is_uppercase)
+                            && lint_store.find_lints(&format!("clippy::{}", name_lower)).is_ok() {
+                            db.span_suggestion(
+                                lint.span(),
+                                "lowercase the lint name",
+                                format!("clippy::{}", name_lower),
+                                Applicability::MachineApplicable,
+                            );
+                        } else if let Some(sugg) = sugg {
+                            db.span_suggestion(
+                                lint.span(),
+                                "did you mean",
+                                sugg.to_string(),
+                                Applicability::MachineApplicable,
+                            );
                         }
                     }
                 );

tests/ui/unknown_clippy_lints.fixed

@@ -0,0 +1,18 @@
+// run-rustfix
+
+#![warn(clippy::pedantic)]
+// Should suggest lowercase
+#![allow(clippy::all)]
+#![warn(clippy::cmp_nan)]
+
+// Should suggest similar clippy lint name
+#[warn(clippy::if_not_else)]
+#[warn(clippy::unnecessary_cast)]
+#[warn(clippy::useless_transmute)]
+// Shouldn't suggest rustc lint name(`dead_code`)
+#[warn(clippy::drop_copy)]
+// Shouldn't suggest removed/deprecated clippy lint name(`unused_collect`)
+#[warn(clippy::unused_self)]
+// Shouldn't suggest renamed clippy lint name(`const_static_lifetime`)
+#[warn(clippy::redundant_static_lifetimes)]
+fn main() {}

tests/ui/unknown_clippy_lints.rs

@@ -1,5 +1,18 @@
-#![allow(clippy::All)]
+// run-rustfix
+
 #![warn(clippy::pedantic)]
+// Should suggest lowercase
+#![allow(clippy::All)]
+#![warn(clippy::CMP_NAN)]
 
+// Should suggest similar clippy lint name
 #[warn(clippy::if_not_els)]
+#[warn(clippy::UNNecsaRy_cAst)]
+#[warn(clippy::useles_transute)]
+// Shouldn't suggest rustc lint name(`dead_code`)
+#[warn(clippy::dead_cod)]
+// Shouldn't suggest removed/deprecated clippy lint name(`unused_collect`)
+#[warn(clippy::unused_colle)]
+// Shouldn't suggest renamed clippy lint name(`const_static_lifetime`)
+#[warn(clippy::const_static_lifetim)]
 fn main() {}

tests/ui/unknown_clippy_lints.stderr

@@ -1,16 +1,52 @@
 error: unknown clippy lint: clippy::if_not_els
-  --> $DIR/unknown_clippy_lints.rs:4:8
+  --> $DIR/unknown_clippy_lints.rs:9:8
    |
 LL | #[warn(clippy::if_not_els)]
-   |        ^^^^^^^^^^^^^^^^^^
+   |        ^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::if_not_else`
    |
    = note: `-D clippy::unknown-clippy-lints` implied by `-D warnings`
 
+error: unknown clippy lint: clippy::UNNecsaRy_cAst
+  --> $DIR/unknown_clippy_lints.rs:10:8
+   |
+LL | #[warn(clippy::UNNecsaRy_cAst)]
+   |        ^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::unnecessary_cast`
+
+error: unknown clippy lint: clippy::useles_transute
+  --> $DIR/unknown_clippy_lints.rs:11:8
+   |
+LL | #[warn(clippy::useles_transute)]
+   |        ^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::useless_transmute`
+
+error: unknown clippy lint: clippy::dead_cod
+  --> $DIR/unknown_clippy_lints.rs:13:8
+   |
+LL | #[warn(clippy::dead_cod)]
+   |        ^^^^^^^^^^^^^^^^ help: did you mean: `clippy::drop_copy`
+
+error: unknown clippy lint: clippy::unused_colle
+  --> $DIR/unknown_clippy_lints.rs:15:8
+   |
+LL | #[warn(clippy::unused_colle)]
+   |        ^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::unused_self`
+
+error: unknown clippy lint: clippy::const_static_lifetim
+  --> $DIR/unknown_clippy_lints.rs:17:8
+   |
+LL | #[warn(clippy::const_static_lifetim)]
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::redundant_static_lifetimes`
+
 error: unknown clippy lint: clippy::All
-  --> $DIR/unknown_clippy_lints.rs:1:10
+  --> $DIR/unknown_clippy_lints.rs:5:10
    |
 LL | #![allow(clippy::All)]
-   |          ^^^^^^^^^^^ help: lowercase the lint name: `all`
+   |          ^^^^^^^^^^^ help: lowercase the lint name: `clippy::all`
+
+error: unknown clippy lint: clippy::CMP_NAN
+  --> $DIR/unknown_clippy_lints.rs:6:9
+   |
+LL | #![warn(clippy::CMP_NAN)]
+   |         ^^^^^^^^^^^^^^^ help: lowercase the lint name: `clippy::cmp_nan`
 
-error: aborting due to 2 previous errors
+error: aborting due to 8 previous errors