Dereference one less on search_is_some and make it auto-fixable

Author: BO41

clippy_lints/src/methods/mod.rs

@@ -2386,31 +2386,40 @@ fn lint_search_is_some<'a, 'tcx>(
         let search_snippet = snippet(cx, search_args[1].span, "..");
         if search_snippet.lines().count() <= 1 {
             // suggest `any(|x| ..)` instead of `any(|&x| ..)` for `find(|&x| ..).is_some()`
+            // suggest `any(|..| *..)` instead of `any(|..| **..)` for `find(|..| **..).is_some()`
             let any_search_snippet = if_chain! {
                 if search_method == "find";
                 if let hir::ExprKind::Closure(_, _, body_id, ..) = search_args[1].node;
                 let closure_body = cx.tcx.hir().body(body_id);
                 if let Some(closure_arg) = closure_body.params.get(0);
                 if let hir::PatKind::Ref(..) = closure_arg.pat.node;
                 then {
-                    Some(search_snippet.replacen('&', "", 1))
+                    match &closure_arg.pat.node {
+                        hir::PatKind::Ref(..) => Some(search_snippet.replacen('&', "", 1)),
+                        hir::PatKind::Binding(_, _, expr, _) => {
+                            let closure_arg_snip = snippet(cx, expr.span, "..");
+                            Some(search_snippet.replace(&format!("*{}", closure_arg_snip), &closure_arg_snip))
+                        }
+                        _ => None,
+                    }
                 } else {
                     None
                 }
             };
             // add note if not multi-line
-            span_note_and_lint(
+            span_lint_and_sugg(
                 cx,
                 SEARCH_IS_SOME,
                 expr.span,
                 &msg,
-                expr.span,
-                &format!(
-                    "replace `{0}({1}).is_some()` with `any({2})`",
-                    search_method,
-                    search_snippet,
-                    any_search_snippet.as_ref().map_or(&*search_snippet, String::as_str)
+                "try this",
+                format!(
+                    "any({})",
+                    any_search_snippet
+                        .as_ref()
+                        .map_or(&*search_snippet, String::as_str)
                 ),
+                Applicability::MachineApplicable,
             );
         } else {
             span_lint(cx, SEARCH_IS_SOME, expr.span, &msg);

tests/ui/methods.fixed

@@ -0,0 +1,306 @@
+// aux-build:option_helpers.rs
+// compile-flags: --edition 2018
+// run-rustfix
+
+#![warn(clippy::all, clippy::pedantic, clippy::option_unwrap_used)]
+#![allow(
+    clippy::blacklisted_name,
+    unused,
+    clippy::print_stdout,
+    clippy::non_ascii_literal,
+    clippy::new_without_default,
+    clippy::missing_docs_in_private_items,
+    clippy::needless_pass_by_value,
+    clippy::default_trait_access,
+    clippy::use_self,
+    clippy::useless_format,
+    clippy::wrong_self_convention
+)]
+
+#[macro_use]
+extern crate option_helpers;
+
+use std::collections::BTreeMap;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::collections::VecDeque;
+use std::iter::FromIterator;
+use std::ops::Mul;
+use std::rc::{self, Rc};
+use std::sync::{self, Arc};
+
+use option_helpers::IteratorFalsePositives;
+
+pub struct T;
+
+impl T {
+    pub fn add(self, other: T) -> T {
+        self
+    }
+
+    // no error, not public interface
+    pub(crate) fn drop(&mut self) {}
+
+    // no error, private function
+    fn neg(self) -> Self {
+        self
+    }
+
+    // no error, private function
+    fn eq(&self, other: T) -> bool {
+        true
+    }
+
+    // No error; self is a ref.
+    fn sub(&self, other: T) -> &T {
+        self
+    }
+
+    // No error; different number of arguments.
+    fn div(self) -> T {
+        self
+    }
+
+    // No error; wrong return type.
+    fn rem(self, other: T) {}
+
+    // Fine
+    fn into_u32(self) -> u32 {
+        0
+    }
+
+    fn into_u16(&self) -> u16 {
+        0
+    }
+
+    fn to_something(self) -> u32 {
+        0
+    }
+
+    fn new(self) -> Self {
+        unimplemented!();
+    }
+}
+
+struct Lt<'a> {
+    foo: &'a u32,
+}
+
+impl<'a> Lt<'a> {
+    // The lifetime is different, but that’s irrelevant; see issue #734.
+    #[allow(clippy::needless_lifetimes)]
+    pub fn new<'b>(s: &'b str) -> Lt<'b> {
+        unimplemented!()
+    }
+}
+
+struct Lt2<'a> {
+    foo: &'a u32,
+}
+
+impl<'a> Lt2<'a> {
+    // The lifetime is different, but that’s irrelevant; see issue #734.
+    pub fn new(s: &str) -> Lt2 {
+        unimplemented!()
+    }
+}
+
+struct Lt3<'a> {
+    foo: &'a u32,
+}
+
+impl<'a> Lt3<'a> {
+    // The lifetime is different, but that’s irrelevant; see issue #734.
+    pub fn new() -> Lt3<'static> {
+        unimplemented!()
+    }
+}
+
+#[derive(Clone, Copy)]
+struct U;
+
+impl U {
+    fn new() -> Self {
+        U
+    }
+    // Ok because `U` is `Copy`.
+    fn to_something(self) -> u32 {
+        0
+    }
+}
+
+struct V<T> {
+    _dummy: T,
+}
+
+impl<T> V<T> {
+    fn new() -> Option<V<T>> {
+        None
+    }
+}
+
+struct AsyncNew;
+
+impl AsyncNew {
+    async fn new() -> Option<Self> {
+        None
+    }
+}
+
+struct BadNew;
+
+impl BadNew {
+    fn new() -> i32 {
+        0
+    }
+}
+
+impl Mul<T> for T {
+    type Output = T;
+    // No error, obviously.
+    fn mul(self, other: T) -> T {
+        self
+    }
+}
+
+/// Checks implementation of the following lints:
+/// * `OPTION_MAP_UNWRAP_OR`
+/// * `OPTION_MAP_UNWRAP_OR_ELSE`
+#[rustfmt::skip]
+fn option_methods() {
+    let opt = Some(1);
+
+    // Check `OPTION_MAP_UNWRAP_OR`.
+    // Single line case.
+    let _ = opt.map(|x| x + 1)
+                // Should lint even though this call is on a separate line.
+               .unwrap_or(0);
+    // Multi-line cases.
+    let _ = opt.map(|x| {
+                        x + 1
+                    }
+              ).unwrap_or(0);
+    let _ = opt.map(|x| x + 1)
+               .unwrap_or({
+                    0
+                });
+    // Single line `map(f).unwrap_or(None)` case.
+    let _ = opt.map(|x| Some(x + 1)).unwrap_or(None);
+    // Multi-line `map(f).unwrap_or(None)` cases.
+    let _ = opt.map(|x| {
+        Some(x + 1)
+    }
+    ).unwrap_or(None);
+    let _ = opt
+        .map(|x| Some(x + 1))
+        .unwrap_or(None);
+    // macro case
+    let _ = opt_map!(opt, |x| x + 1).unwrap_or(0); // should not lint
+
+    // Should not lint if not copyable
+    let id: String = "identifier".to_string();
+    let _ = Some("prefix").map(|p| format!("{}.{}", p, id)).unwrap_or(id);
+    // ...but DO lint if the `unwrap_or` argument is not used in the `map`
+    let id: String = "identifier".to_string();
+    let _ = Some("prefix").map(|p| format!("{}.", p)).unwrap_or(id);
+
+    // Check OPTION_MAP_UNWRAP_OR_ELSE
+    // single line case
+    let _ = opt.map(|x| x + 1)
+                // Should lint even though this call is on a separate line.
+               .unwrap_or_else(|| 0);
+    // Multi-line cases.
+    let _ = opt.map(|x| {
+                        x + 1
+                    }
+              ).unwrap_or_else(|| 0);
+    let _ = opt.map(|x| x + 1)
+               .unwrap_or_else(||
+                    0
+                );
+    // Macro case.
+    // Should not lint.
+    let _ = opt_map!(opt, |x| x + 1).unwrap_or_else(|| 0);
+
+    // Issue #4144
+    {
+        let mut frequencies = HashMap::new();
+        let word = "foo";
+
+        frequencies
+            .get_mut(word)
+            .map(|count| {
+                *count += 1;
+            })
+            .unwrap_or_else(|| {
+                frequencies.insert(word.to_owned(), 1);
+            });
+    }
+}
+
+/// Checks implementation of `FILTER_NEXT` lint.
+#[rustfmt::skip]
+fn filter_next() {
+    let v = vec![3, 2, 1, 0, -1, -2, -3];
+
+    // Single-line case.
+    let _ = v.iter().filter(|&x| *x < 0).next();
+
+    // Multi-line case.
+    let _ = v.iter().filter(|&x| {
+                                *x < 0
+                            }
+                   ).next();
+
+    // Check that hat we don't lint if the caller is not an `Iterator`.
+    let foo = IteratorFalsePositives { foo: 0 };
+    let _ = foo.filter().next();
+}
+
+/// Checks implementation of `SEARCH_IS_SOME` lint.
+#[rustfmt::skip]
+fn search_is_some() {
+    let v = vec![3, 2, 1, 0, -1, -2, -3];
+    let y = &&42;
+
+    // Check `find().is_some()`, single-line case.
+    let _ = any(|x| *x < 0);
+    let _ = any(|x| **y == x); // one dereference less
+    let _ = any(|x| x == 0);
+
+    // Check `find().is_some()`, multi-line case.
+    let _ = v.iter().find(|&x| {
+                              *x < 0
+                          }
+                   ).is_some();
+
+    // Check `position().is_some()`, single-line case.
+    let _ = any(|&x| x < 0);
+
+    // Check `position().is_some()`, multi-line case.
+    let _ = v.iter().position(|&x| {
+                                  x < 0
+                              }
+                   ).is_some();
+
+    // Check `rposition().is_some()`, single-line case.
+    let _ = any(|&x| x < 0);
+
+    // Check `rposition().is_some()`, multi-line case.
+    let _ = v.iter().rposition(|&x| {
+                                   x < 0
+                               }
+                   ).is_some();
+
+    // Check that we don't lint if the caller is not an `Iterator`.
+    let foo = IteratorFalsePositives { foo: 0 };
+    let _ = foo.find().is_some();
+    let _ = foo.position().is_some();
+    let _ = foo.rposition().is_some();
+}
+
+#[allow(clippy::similar_names)]
+fn main() {
+    let opt = Some(0);
+    let _ = opt.unwrap();
+}

tests/ui/methods.rs

@@ -1,5 +1,6 @@
 // aux-build:option_helpers.rs
 // compile-flags: --edition 2018
+// run-rustfix
 
 #![warn(clippy::all, clippy::pedantic, clippy::option_unwrap_used)]
 #![allow(
@@ -260,9 +261,12 @@ fn filter_next() {
 #[rustfmt::skip]
 fn search_is_some() {
     let v = vec![3, 2, 1, 0, -1, -2, -3];
+    let y = &&42;
 
     // Check `find().is_some()`, single-line case.
     let _ = v.iter().find(|&x| *x < 0).is_some();
+    let _ = (0..1).find(|x| **y == *x).is_some(); // one dereference less
+    let _ = (0..1).find(|x| *x == 0).is_some();
 
     // Check `find().is_some()`, multi-line case.
     let _ = v.iter().find(|&x| {