diff options
Diffstat (limited to 'clippy_lints/src/methods/mod.rs')
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 281 |
1 files changed, 178 insertions, 103 deletions
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index 8a76ba0b064..38165ab4fb2 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -54,6 +54,7 @@ mod map_flatten; mod map_identity; mod map_unwrap_or; mod mut_mutex_lock; +mod needless_collect; mod needless_option_as_deref; mod needless_option_take; mod no_effect_replace; @@ -69,6 +70,8 @@ mod path_buf_push_overwrite; mod range_zip_with_len; mod repeat_once; mod search_is_some; +mod seek_from_current; +mod seek_to_start_instead_of_rewind; mod single_char_add_str; mod single_char_insert_string; mod single_char_pattern; @@ -101,12 +104,11 @@ mod zst_offset; use bind_instead_of_map::BindInsteadOfMap; use clippy_utils::consts::{constant, Constant}; use clippy_utils::diagnostics::{span_lint, span_lint_and_help}; -use clippy_utils::ty::{contains_adt_constructor, implements_trait, is_copy, is_type_diagnostic_item}; -use clippy_utils::{contains_return, is_trait_method, iter_input_pats, meets_msrv, msrvs, return_ty}; +use clippy_utils::ty::{contains_ty_adt_constructor_opaque, implements_trait, is_copy, is_type_diagnostic_item}; +use clippy_utils::{contains_return, is_bool, is_trait_method, iter_input_pats, meets_msrv, msrvs, return_ty}; use if_chain::if_chain; use rustc_hir as hir; -use rustc_hir::def::Res; -use rustc_hir::{Expr, ExprKind, PrimTy, QPath, TraitItem, TraitItemKind}; +use rustc_hir::{Expr, ExprKind, TraitItem, TraitItemKind}; use rustc_hir_analysis::hir_ty_to_ty; use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_middle::lint::in_external_macro; @@ -156,9 +158,9 @@ declare_clippy_lint! { /// ``` /// Use instead: /// ```rust - /// let hello = "hesuo worpd".replace(&['s', 'u', 'p'], "l"); + /// let hello = "hesuo worpd".replace(['s', 'u', 'p'], "l"); /// ``` - #[clippy::version = "1.64.0"] + #[clippy::version = "1.65.0"] pub COLLAPSIBLE_STR_REPLACE, perf, "collapse consecutive calls to str::replace (2 or more) into a single call" @@ -829,32 +831,30 @@ declare_clippy_lint! { /// etc. instead. /// /// ### Why is this bad? - /// The function will always be called and potentially - /// allocate an object acting as the default. + /// The function will always be called. This is only bad if it allocates or + /// does some non-trivial amount of work. /// /// ### Known problems - /// If the function has side-effects, not calling it will - /// change the semantic of the program, but you shouldn't rely on that anyway. + /// If the function has side-effects, not calling it will change the + /// semantic of the program, but you shouldn't rely on that. + /// + /// The lint also cannot figure out whether the function you call is + /// actually expensive to call or not. /// /// ### Example /// ```rust /// # let foo = Some(String::new()); - /// foo.unwrap_or(String::new()); + /// foo.unwrap_or(String::from("empty")); /// ``` /// /// Use instead: /// ```rust /// # let foo = Some(String::new()); - /// foo.unwrap_or_else(String::new); - /// - /// // or - /// - /// # let foo = Some(String::new()); - /// foo.unwrap_or_default(); + /// foo.unwrap_or_else(|| String::from("empty")); /// ``` #[clippy::version = "pre 1.29.0"] pub OR_FUN_CALL, - perf, + nursery, "using any `*or` method with a function call, which suggests `*or_else`" } @@ -1728,7 +1728,7 @@ declare_clippy_lint! { declare_clippy_lint! { /// ### What it does - /// Checks for usage of `_.as_ref().map(Deref::deref)` or it's aliases (such as String::as_str). + /// Checks for usage of `_.as_ref().map(Deref::deref)` or its aliases (such as String::as_str). /// /// ### Why is this bad? /// Readability, this can be written more concisely as @@ -2094,8 +2094,7 @@ declare_clippy_lint! { /// let s = "Hello world!"; /// let cow = Cow::Borrowed(s); /// - /// let data = cow.into_owned(); - /// assert!(matches!(data, String)) + /// let _data: String = cow.into_owned(); /// ``` #[clippy::version = "1.65.0"] pub SUSPICIOUS_TO_OWNED, @@ -2426,7 +2425,7 @@ declare_clippy_lint! { /// ### Known problems /// /// The type of the resulting iterator might become incompatible with its usage - #[clippy::version = "1.64.0"] + #[clippy::version = "1.65.0"] pub ITER_ON_SINGLE_ITEMS, nursery, "Iterator for array of length 1" @@ -2458,7 +2457,7 @@ declare_clippy_lint! { /// ### Known problems /// /// The type of the resulting iterator might become incompatible with its usage - #[clippy::version = "1.64.0"] + #[clippy::version = "1.65.0"] pub ITER_ON_EMPTY_COLLECTIONS, nursery, "Iterator for empty array" @@ -3066,6 +3065,102 @@ declare_clippy_lint! { "iterating on map using `iter` when `keys` or `values` would do" } +declare_clippy_lint! { + /// ### What it does + /// + /// Checks an argument of `seek` method of `Seek` trait + /// and if it start seek from `SeekFrom::Current(0)`, suggests `stream_position` instead. + /// + /// ### Why is this bad? + /// + /// Readability. Use dedicated method. + /// + /// ### Example + /// + /// ```rust,no_run + /// use std::fs::File; + /// use std::io::{self, Write, Seek, SeekFrom}; + /// + /// fn main() -> io::Result<()> { + /// let mut f = File::create("foo.txt")?; + /// f.write_all(b"Hello")?; + /// eprintln!("Written {} bytes", f.seek(SeekFrom::Current(0))?); + /// + /// Ok(()) + /// } + /// ``` + /// Use instead: + /// ```rust,no_run + /// use std::fs::File; + /// use std::io::{self, Write, Seek, SeekFrom}; + /// + /// fn main() -> io::Result<()> { + /// let mut f = File::create("foo.txt")?; + /// f.write_all(b"Hello")?; + /// eprintln!("Written {} bytes", f.stream_position()?); + /// + /// Ok(()) + /// } + /// ``` + #[clippy::version = "1.66.0"] + pub SEEK_FROM_CURRENT, + complexity, + "use dedicated method for seek from current position" +} + +declare_clippy_lint! { + /// ### What it does + /// + /// Checks for jumps to the start of a stream that implements `Seek` + /// and uses the `seek` method providing `Start` as parameter. + /// + /// ### Why is this bad? + /// + /// Readability. There is a specific method that was implemented for + /// this exact scenario. + /// + /// ### Example + /// ```rust + /// # use std::io; + /// fn foo<T: io::Seek>(t: &mut T) { + /// t.seek(io::SeekFrom::Start(0)); + /// } + /// ``` + /// Use instead: + /// ```rust + /// # use std::io; + /// fn foo<T: io::Seek>(t: &mut T) { + /// t.rewind(); + /// } + /// ``` + #[clippy::version = "1.66.0"] + pub SEEK_TO_START_INSTEAD_OF_REWIND, + complexity, + "jumping to the start of stream using `seek` method" +} + +declare_clippy_lint! { + /// ### What it does + /// Checks for functions collecting an iterator when collect + /// is not needed. + /// + /// ### Why is this bad? + /// `collect` causes the allocation of a new data structure, + /// when this allocation may not be needed. + /// + /// ### Example + /// ```rust + /// # let iterator = vec![1].into_iter(); + /// let len = iterator.clone().collect::<Vec<_>>().len(); + /// // should be + /// let len = iterator.count(); + /// ``` + #[clippy::version = "1.30.0"] + pub NEEDLESS_COLLECT, + nursery, + "collecting an iterator when collect is not needed" +} + pub struct Methods { avoid_breaking_exported_api: bool, msrv: Option<RustcVersion>, @@ -3190,16 +3285,19 @@ impl_lint_pass!(Methods => [ VEC_RESIZE_TO_ZERO, VERBOSE_FILE_READS, ITER_KV_MAP, + SEEK_FROM_CURRENT, + SEEK_TO_START_INSTEAD_OF_REWIND, + NEEDLESS_COLLECT, ]); /// Extracts a method call name, args, and `Span` of the method name. fn method_call<'tcx>( recv: &'tcx hir::Expr<'tcx>, -) -> Option<(&'tcx str, &'tcx hir::Expr<'tcx>, &'tcx [hir::Expr<'tcx>], Span)> { - if let ExprKind::MethodCall(path, receiver, args, _) = recv.kind { +) -> Option<(&'tcx str, &'tcx hir::Expr<'tcx>, &'tcx [hir::Expr<'tcx>], Span, Span)> { + if let ExprKind::MethodCall(path, receiver, args, call_span) = recv.kind { if !args.iter().any(|e| e.span.from_expansion()) && !receiver.span.from_expansion() { let name = path.ident.name.as_str(); - return Some((name, receiver, args, path.ident.span)); + return Some((name, receiver, args, path.ident.span, call_span)); } } None @@ -3316,36 +3414,10 @@ impl<'tcx> LateLintPass<'tcx> for Methods { if let hir::ImplItemKind::Fn(_, _) = impl_item.kind { let ret_ty = return_ty(cx, impl_item.hir_id()); - // walk the return type and check for Self (this does not check associated types) - if let Some(self_adt) = self_ty.ty_adt_def() { - if contains_adt_constructor(ret_ty, self_adt) { - return; - } - } else if ret_ty.contains(self_ty) { + if contains_ty_adt_constructor_opaque(cx, ret_ty, self_ty) { return; } - // if return type is impl trait, check the associated types - if let ty::Opaque(def_id, _) = *ret_ty.kind() { - // one of the associated types must be Self - for &(predicate, _span) in cx.tcx.explicit_item_bounds(def_id) { - if let ty::PredicateKind::Projection(projection_predicate) = predicate.kind().skip_binder() { - let assoc_ty = match projection_predicate.term.unpack() { - ty::TermKind::Ty(ty) => ty, - ty::TermKind::Const(_c) => continue, - }; - // walk the associated type and check for Self - if let Some(self_adt) = self_ty.ty_adt_def() { - if contains_adt_constructor(assoc_ty, self_adt) { - return; - } - } else if assoc_ty.contains(self_ty) { - return; - } - } - } - } - if name == "new" && ret_ty != self_ty { span_lint( cx, @@ -3411,7 +3483,7 @@ impl<'tcx> LateLintPass<'tcx> for Methods { impl Methods { #[allow(clippy::too_many_lines)] fn check_methods<'tcx>(&self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { - if let Some((name, recv, args, span)) = method_call(expr) { + if let Some((name, recv, args, span, call_span)) = method_call(expr) { match (name, args) { ("add" | "offset" | "sub" | "wrapping_offset" | "wrapping_add" | "wrapping_sub", [_arg]) => { zst_offset::check(cx, expr, recv); @@ -3430,28 +3502,31 @@ impl Methods { ("as_ref", []) => useless_asref::check(cx, expr, "as_ref", recv), ("assume_init", []) => uninit_assumed_init::check(cx, expr, recv), ("cloned", []) => cloned_instead_of_copied::check(cx, expr, recv, span, self.msrv), - ("collect", []) => match method_call(recv) { - Some((name @ ("cloned" | "copied"), recv2, [], _)) => { - iter_cloned_collect::check(cx, name, expr, recv2); - }, - Some(("map", m_recv, [m_arg], _)) => { - map_collect_result_unit::check(cx, expr, m_recv, m_arg, recv); - }, - Some(("take", take_self_arg, [take_arg], _)) => { - if meets_msrv(self.msrv, msrvs::STR_REPEAT) { - manual_str_repeat::check(cx, expr, recv, take_self_arg, take_arg); - } - }, - _ => {}, + ("collect", []) if is_trait_method(cx, expr, sym::Iterator) => { + needless_collect::check(cx, span, expr, recv, call_span); + match method_call(recv) { + Some((name @ ("cloned" | "copied"), recv2, [], _, _)) => { + iter_cloned_collect::check(cx, name, expr, recv2); + }, + Some(("map", m_recv, [m_arg], _, _)) => { + map_collect_result_unit::check(cx, expr, m_recv, m_arg); + }, + Some(("take", take_self_arg, [take_arg], _, _)) => { + if meets_msrv(self.msrv, msrvs::STR_REPEAT) { + manual_str_repeat::check(cx, expr, recv, take_self_arg, take_arg); + } + }, + _ => {}, + } }, ("count", []) if is_trait_method(cx, expr, sym::Iterator) => match method_call(recv) { - Some(("cloned", recv2, [], _)) => iter_overeager_cloned::check(cx, expr, recv, recv2, true, false), - Some((name2 @ ("into_iter" | "iter" | "iter_mut"), recv2, [], _)) => { + Some(("cloned", recv2, [], _, _)) => iter_overeager_cloned::check(cx, expr, recv, recv2, true, false), + Some((name2 @ ("into_iter" | "iter" | "iter_mut"), recv2, [], _, _)) => { iter_count::check(cx, expr, recv2, name2); }, - Some(("map", _, [arg], _)) => suspicious_map::check(cx, expr, recv, arg), - Some(("filter", recv2, [arg], _)) => bytecount::check(cx, expr, recv2, arg), - Some(("bytes", recv2, [], _)) => bytes_count_to_len::check(cx, expr, recv, recv2), + Some(("map", _, [arg], _, _)) => suspicious_map::check(cx, expr, recv, arg), + Some(("filter", recv2, [arg], _, _)) => bytecount::check(cx, expr, recv2, arg), + Some(("bytes", recv2, [], _, _)) => bytes_count_to_len::check(cx, expr, recv, recv2), _ => {}, }, ("drain", [arg]) => { @@ -3463,8 +3538,8 @@ impl Methods { } }, ("expect", [_]) => match method_call(recv) { - Some(("ok", recv, [], _)) => ok_expect::check(cx, expr, recv), - Some(("err", recv, [], err_span)) => err_expect::check(cx, expr, recv, self.msrv, span, err_span), + Some(("ok", recv, [], _, _)) => ok_expect::check(cx, expr, recv), + Some(("err", recv, [], err_span, _)) => err_expect::check(cx, expr, recv, self.msrv, span, err_span), _ => expect_used::check(cx, expr, recv, false, self.allow_expect_in_tests), }, ("expect_err", [_]) => expect_used::check(cx, expr, recv, true, self.allow_expect_in_tests), @@ -3484,13 +3559,13 @@ impl Methods { flat_map_option::check(cx, expr, arg, span); }, ("flatten", []) => match method_call(recv) { - 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, recv, recv2, false, true), + 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, recv, recv2, false, true), _ => {}, }, ("fold", [init, acc]) => unnecessary_fold::check(cx, expr, init, acc, span), ("for_each", [_]) => { - if let Some(("inspect", _, [_], span2)) = method_call(recv) { + if let Some(("inspect", _, [_], span2, _)) = method_call(recv) { inspect_for_each::check(cx, expr, span2); } }, @@ -3510,12 +3585,12 @@ impl Methods { iter_on_single_or_empty_collections::check(cx, expr, name, recv); }, ("join", [join_arg]) => { - if let Some(("collect", _, _, span)) = method_call(recv) { + if let Some(("collect", _, _, span, _)) = method_call(recv) { unnecessary_join::check(cx, expr, recv, join_arg, span); } }, ("last", []) | ("skip", [_]) => { - if let Some((name2, recv2, args2, _span2)) = method_call(recv) { + if let Some((name2, recv2, args2, _span2, _)) = method_call(recv) { if let ("cloned", []) = (name2, args2) { iter_overeager_cloned::check(cx, expr, recv, recv2, false, false); } @@ -3527,13 +3602,13 @@ impl Methods { (name @ ("map" | "map_err"), [m_arg]) => { if name == "map" { map_clone::check(cx, expr, recv, m_arg, self.msrv); - if let Some((map_name @ ("iter" | "into_iter"), recv2, _, _)) = method_call(recv) { + if let Some((map_name @ ("iter" | "into_iter"), recv2, _, _, _)) = method_call(recv) { iter_kv_map::check(cx, map_name, expr, recv2, m_arg); } } else { map_err_ignore::check(cx, expr, m_arg); } - if let Some((name, recv2, args, span2)) = method_call(recv) { + if let Some((name, recv2, args, span2,_)) = method_call(recv) { match (name, args) { ("as_mut", []) => option_as_ref_deref::check(cx, expr, recv2, m_arg, true, self.msrv), ("as_ref", []) => option_as_ref_deref::check(cx, expr, recv2, m_arg, false, self.msrv), @@ -3553,7 +3628,7 @@ impl Methods { manual_ok_or::check(cx, expr, recv, def, map); }, ("next", []) => { - if let Some((name2, recv2, args2, _)) = method_call(recv) { + if let Some((name2, recv2, args2, _, _)) = method_call(recv) { match (name2, args2) { ("cloned", []) => iter_overeager_cloned::check(cx, expr, recv, recv2, false, false), ("filter", [arg]) => filter_next::check(cx, expr, recv2, arg), @@ -3566,10 +3641,10 @@ impl Methods { } }, ("nth", [n_arg]) => match method_call(recv) { - Some(("bytes", recv2, [], _)) => bytes_nth::check(cx, expr, recv2, n_arg), - Some(("cloned", recv2, [], _)) => iter_overeager_cloned::check(cx, expr, recv, recv2, false, false), - Some(("iter", recv2, [], _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, false), - Some(("iter_mut", recv2, [], _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, true), + Some(("bytes", recv2, [], _, _)) => bytes_nth::check(cx, expr, recv2, n_arg), + Some(("cloned", recv2, [], _, _)) => iter_overeager_cloned::check(cx, expr, recv, recv2, false, false), + Some(("iter", recv2, [], _, _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, false), + Some(("iter_mut", recv2, [], _, _)) => iter_nth::check(cx, expr, recv2, recv, n_arg, true), _ => iter_nth_zero::check(cx, expr, recv, n_arg), }, ("ok_or_else", [arg]) => unnecessary_lazy_eval::check(cx, expr, recv, arg, "ok_or"), @@ -3604,6 +3679,14 @@ impl Methods { ("resize", [count_arg, default_arg]) => { vec_resize_to_zero::check(cx, expr, count_arg, default_arg, span); }, + ("seek", [arg]) => { + if meets_msrv(self.msrv, msrvs::SEEK_FROM_CURRENT) { + seek_from_current::check(cx, expr, recv, arg); + } + if meets_msrv(self.msrv, msrvs::SEEK_REWIND) { + seek_to_start_instead_of_rewind::check(cx, expr, recv, arg, span); + } + }, ("sort", []) => { stable_sort_primitive::check(cx, expr, recv); }, @@ -3626,7 +3709,7 @@ impl Methods { }, ("step_by", [arg]) => iterator_step_by_zero::check(cx, expr, arg), ("take", [_arg]) => { - if let Some((name2, recv2, args2, _span2)) = method_call(recv) { + if let Some((name2, recv2, args2, _span2, _)) = method_call(recv) { if let ("cloned", []) = (name2, args2) { iter_overeager_cloned::check(cx, expr, recv, recv2, false, false); } @@ -3649,13 +3732,13 @@ impl Methods { }, ("unwrap", []) => { match method_call(recv) { - Some(("get", recv, [get_arg], _)) => { + Some(("get", recv, [get_arg], _, _)) => { get_unwrap::check(cx, expr, recv, get_arg, false); }, - Some(("get_mut", recv, [get_arg], _)) => { + Some(("get_mut", recv, [get_arg], _, _)) => { get_unwrap::check(cx, expr, recv, get_arg, true); }, - Some(("or", recv, [or_arg], or_span)) => { + Some(("or", recv, [or_arg], or_span, _)) => { or_then_unwrap::check(cx, expr, recv, or_arg, or_span); }, _ => {}, @@ -3664,19 +3747,19 @@ impl Methods { }, ("unwrap_err", []) => unwrap_used::check(cx, expr, recv, true, self.allow_unwrap_in_tests), ("unwrap_or", [u_arg]) => match method_call(recv) { - Some((arith @ ("checked_add" | "checked_sub" | "checked_mul"), lhs, [rhs], _)) => { + Some((arith @ ("checked_add" | "checked_sub" | "checked_mul"), lhs, [rhs], _, _)) => { manual_saturating_arithmetic::check(cx, expr, lhs, rhs, u_arg, &arith["checked_".len()..]); }, - Some(("map", m_recv, [m_arg], span)) => { + Some(("map", m_recv, [m_arg], span, _)) => { option_map_unwrap_or::check(cx, expr, m_recv, m_arg, recv, u_arg, span); }, - Some(("then_some", t_recv, [t_arg], _)) => { + Some(("then_some", t_recv, [t_arg], _, _)) => { obfuscated_if_else::check(cx, expr, t_recv, t_arg, u_arg); }, _ => {}, }, ("unwrap_or_else", [u_arg]) => match method_call(recv) { - Some(("map", recv, [map_arg], _)) + Some(("map", recv, [map_arg], _, _)) if map_unwrap_or::check(cx, expr, recv, map_arg, u_arg, self.msrv) => {}, _ => { unwrap_or_else_default::check(cx, expr, recv, u_arg); @@ -3697,7 +3780,7 @@ impl Methods { } fn check_is_some_is_none(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, is_some: bool) { - if let Some((name @ ("find" | "position" | "rposition"), f_recv, [arg], span)) = method_call(recv) { + if let Some((name @ ("find" | "position" | "rposition"), f_recv, [arg], span, _)) = method_call(recv) { search_is_some::check(cx, expr, name, is_some, f_recv, arg, recv, span); } } @@ -3906,14 +3989,6 @@ impl OutType { } } -fn is_bool(ty: &hir::Ty<'_>) -> bool { - if let hir::TyKind::Path(QPath::Resolved(_, path)) = ty.kind { - matches!(path.res, Res::PrimTy(PrimTy::Bool)) - } else { - false - } -} - fn fn_header_equals(expected: hir::FnHeader, actual: hir::FnHeader) -> bool { expected.constness == actual.constness && expected.unsafety == actual.unsafety |