mod iter_nth_zero;
mod iter_overeager_cloned;
mod iter_skip_next;
+mod iter_with_drain;
mod iterator_step_by_zero;
mod manual_saturating_arithmetic;
mod manual_str_repeat;
mod option_map_or_none;
mod option_map_unwrap_or;
mod or_fun_call;
+mod or_then_unwrap;
mod search_is_some;
mod single_char_add_str;
mod single_char_insert_string;
mod unnecessary_filter_map;
mod unnecessary_fold;
mod unnecessary_iter_cloned;
+mod unnecessary_join;
mod unnecessary_lazy_eval;
mod unnecessary_to_owned;
mod unwrap_or_else_default;
///
/// ### Why is this bad?
/// Readability, this can be written more concisely as
- /// `_.flat_map(_)`
+ /// `_.flat_map(_)` for `Iterator` or `_.and_then(_)` for `Option`
///
/// ### Example
/// ```rust
/// let vec = vec![vec![1]];
+ /// let opt = Some(5);
///
/// // Bad
/// vec.iter().map(|x| x.iter()).flatten();
+ /// opt.map(|x| Some(x * 2)).flatten();
///
/// // Good
/// vec.iter().flat_map(|x| x.iter());
+ /// opt.and_then(|x| Some(x * 2));
/// ```
#[clippy::version = "1.31.0"]
pub MAP_FLATTEN,
"using any `*or` method with a function call, which suggests `*or_else`"
}
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for `.or(…).unwrap()` calls to Options and Results.
+ ///
+ /// ### Why is this bad?
+ /// You should use `.unwrap_or(…)` instead for clarity.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # let fallback = "fallback";
+ /// // Result
+ /// # type Error = &'static str;
+ /// # let result: Result<&str, Error> = Err("error");
+ /// let value = result.or::<Error>(Ok(fallback)).unwrap();
+ ///
+ /// // Option
+ /// # let option: Option<&str> = None;
+ /// let value = option.or(Some(fallback)).unwrap();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// # let fallback = "fallback";
+ /// // Result
+ /// # let result: Result<&str, &str> = Err("error");
+ /// let value = result.unwrap_or(fallback);
+ ///
+ /// // Option
+ /// # let option: Option<&str> = None;
+ /// let value = option.unwrap_or(fallback);
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub OR_THEN_UNWRAP,
+ complexity,
+ "checks for `.or(…).unwrap()` calls to Options and Results."
+}
+
declare_clippy_lint! {
/// ### What it does
/// Checks for calls to `.expect(&format!(...))`, `.expect(foo(..))`,
"using `.skip(x).next()` on an iterator"
}
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for use of `.drain(..)` on `Vec` and `VecDeque` for iteration.
+ ///
+ /// ### Why is this bad?
+ /// `.into_iter()` is simpler with better performance.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # use std::collections::HashSet;
+ /// let mut foo = vec![0, 1, 2, 3];
+ /// let bar: HashSet<usize> = foo.drain(..).collect();
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// # use std::collections::HashSet;
+ /// let foo = vec![0, 1, 2, 3];
+ /// let bar: HashSet<usize> = foo.into_iter().collect();
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub ITER_WITH_DRAIN,
+ nursery,
+ "replace `.drain(..)` with `.into_iter()`"
+}
+
declare_clippy_lint! {
/// ### What it does
/// Checks for use of `.get().unwrap()` (or
declare_clippy_lint! {
/// ### What it does
- /// Checks for `filter_map` calls which could be replaced by `filter` or `map`.
+ /// Checks for `filter_map` calls that could be replaced by `filter` or `map`.
/// More specifically it checks if the closure provided is only performing one of the
/// filter or map operations and suggests the appropriate option.
///
"using `filter_map` when a more succinct alternative exists"
}
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for `find_map` calls that could be replaced by `find` or `map`. More
+ /// specifically it checks if the closure provided is only performing one of the
+ /// find or map operations and suggests the appropriate option.
+ ///
+ /// ### Why is this bad?
+ /// Complexity. The intent is also clearer if only a single
+ /// operation is being performed.
+ ///
+ /// ### Example
+ /// ```rust
+ /// let _ = (0..3).find_map(|x| if x > 2 { Some(x) } else { None });
+ ///
+ /// // As there is no transformation of the argument this could be written as:
+ /// let _ = (0..3).find(|&x| x > 2);
+ /// ```
+ ///
+ /// ```rust
+ /// let _ = (0..4).find_map(|x| Some(x + 1));
+ ///
+ /// // As there is no conditional check on the argument this could be written as:
+ /// let _ = (0..4).map(|x| x + 1).next();
+ /// ```
+ #[clippy::version = "1.61.0"]
+ pub UNNECESSARY_FIND_MAP,
+ complexity,
+ "using `find_map` when a more succinct alternative exists"
+}
+
declare_clippy_lint! {
/// ### What it does
/// Checks for `into_iter` calls on references which should be replaced by `iter`
"unnecessary calls to `to_owned`-like functions"
}
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for use of `.collect::<Vec<String>>().join("")` on iterators.
+ ///
+ /// ### Why is this bad?
+ /// `.collect::<String>()` is more concise and usually more performant
+ ///
+ /// ### Example
+ /// ```rust
+ /// let vector = vec!["hello", "world"];
+ /// let output = vector.iter().map(|item| item.to_uppercase()).collect::<Vec<String>>().join("");
+ /// println!("{}", output);
+ /// ```
+ /// The correct use would be:
+ /// ```rust
+ /// let vector = vec!["hello", "world"];
+ /// let output = vector.iter().map(|item| item.to_uppercase()).collect::<String>();
+ /// println!("{}", output);
+ /// ```
+ /// ### Known problems
+ /// While `.collect::<String>()` is more performant in most cases, there are cases where
+ /// using `.collect::<String>()` over `.collect::<Vec<String>>().join("")`
+ /// will prevent loop unrolling and will result in a negative performance impact.
+ #[clippy::version = "1.61.0"]
+ pub UNNECESSARY_JOIN,
+ pedantic,
+ "using `.collect::<Vec<String>>().join(\"\")` on an iterator"
+}
+
pub struct Methods {
avoid_breaking_exported_api: bool,
msrv: Option<RustcVersion>,
OPTION_MAP_OR_NONE,
BIND_INSTEAD_OF_MAP,
OR_FUN_CALL,
+ OR_THEN_UNWRAP,
EXPECT_FUN_CALL,
CHARS_NEXT_CMP,
CHARS_LAST_CMP,
GET_UNWRAP,
STRING_EXTEND_CHARS,
ITER_CLONED_COLLECT,
+ ITER_WITH_DRAIN,
USELESS_ASREF,
UNNECESSARY_FOLD,
UNNECESSARY_FILTER_MAP,
+ UNNECESSARY_FIND_MAP,
INTO_ITER_ON_REF,
SUSPICIOUS_MAP,
UNINIT_ASSUMED_INIT,
MANUAL_SPLIT_ONCE,
NEEDLESS_SPLITN,
UNNECESSARY_TO_OWNED,
+ UNNECESSARY_JOIN,
]);
/// Extracts a method call name, args, and `Span` of the method name.
let method_sig = cx.tcx.fn_sig(impl_item.def_id);
let method_sig = cx.tcx.erase_late_bound_regions(method_sig);
- let first_arg_ty = &method_sig.inputs().iter().next();
+ let first_arg_ty = method_sig.inputs().iter().next();
// check conventions w.r.t. conversion method names and predicates
if let Some(first_arg_ty) = first_arg_ty;
if name == method_config.method_name &&
sig.decl.inputs.len() == method_config.param_count &&
method_config.output_type.matches(&sig.decl.output) &&
- method_config.self_kind.matches(cx, self_ty, first_arg_ty) &&
+ method_config.self_kind.matches(cx, self_ty, *first_arg_ty) &&
fn_header_equals(method_config.fn_header, sig.header) &&
method_config.lifetime_param_cond(impl_item)
{
cx,
name,
self_ty,
- first_arg_ty,
+ *first_arg_ty,
first_arg.pat.span,
implements_trait,
false
Some(("map", [_, arg], _)) => suspicious_map::check(cx, expr, recv, arg),
_ => {},
},
+ ("drain", [arg]) => {
+ iter_with_drain::check(cx, expr, recv, span, arg);
+ },
("expect", [_]) => match method_call(recv) {
Some(("ok", [recv], _)) => ok_expect::check(cx, expr, recv),
_ => expect_used::check(cx, expr, recv),
extend_with_drain::check(cx, expr, recv, arg);
},
("filter_map", [arg]) => {
- unnecessary_filter_map::check(cx, expr, arg);
+ unnecessary_filter_map::check(cx, expr, arg, name);
filter_map_identity::check(cx, expr, arg, span);
},
+ ("find_map", [arg]) => {
+ unnecessary_filter_map::check(cx, expr, arg, name);
+ },
("flat_map", [arg]) => {
flat_map_identity::check(cx, expr, arg, span);
flat_map_option::check(cx, expr, arg, span);
},
(name @ "flatten", args @ []) => match method_call(recv) {
- Some(("map", [recv, map_arg], _)) => map_flatten::check(cx, expr, recv, map_arg),
+ Some(("map", [recv, map_arg], map_span)) => map_flatten::check(cx, expr, recv, map_arg, map_span),
Some(("cloned", [recv2], _)) => iter_overeager_cloned::check(cx, expr, recv2, name, args),
_ => {},
},
("is_file", []) => filetype_is_file::check(cx, expr, recv),
("is_none", []) => check_is_some_is_none(cx, expr, recv, false),
("is_some", []) => check_is_some_is_none(cx, expr, recv, true),
+ ("join", [join_arg]) => {
+ if let Some(("collect", _, span)) = method_call(recv) {
+ unnecessary_join::check(cx, expr, recv, join_arg, span);
+ }
+ },
("last", args @ []) | ("skip", args @ [_]) => {
if let Some((name2, [recv2, args2 @ ..], _span2)) = method_call(recv) {
if let ("cloned", []) = (name2, args2) {
("to_os_string" | "to_owned" | "to_path_buf" | "to_vec", []) => {
implicit_clone::check(cx, name, expr, recv);
},
- ("unwrap", []) => match method_call(recv) {
- Some(("get", [recv, get_arg], _)) => get_unwrap::check(cx, expr, recv, get_arg, false),
- Some(("get_mut", [recv, get_arg], _)) => get_unwrap::check(cx, expr, recv, get_arg, true),
- _ => unwrap_used::check(cx, expr, recv),
+ ("unwrap", []) => {
+ match method_call(recv) {
+ Some(("get", [recv, get_arg], _)) => {
+ get_unwrap::check(cx, expr, recv, get_arg, false);
+ },
+ Some(("get_mut", [recv, get_arg], _)) => {
+ get_unwrap::check(cx, expr, recv, get_arg, true);
+ },
+ Some(("or", [recv, or_arg], or_span)) => {
+ or_then_unwrap::check(cx, expr, recv, or_arg, or_span);
+ },
+ _ => {},
+ }
+ unwrap_used::check(cx, expr, recv);
},
("unwrap_or", [u_arg]) => match method_call(recv) {
Some((arith @ ("checked_add" | "checked_sub" | "checked_mul"), [lhs, rhs], _)) => {
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