diff --git a/clippy_lints/src/mem_replace.rs b/clippy_lints/src/mem_replace.rs index 19087b020771..13f9c9b71f39 100644 --- a/clippy_lints/src/mem_replace.rs +++ b/clippy_lints/src/mem_replace.rs @@ -4,6 +4,7 @@ use crate::utils::{ }; use if_chain::if_chain; use rustc_errors::Applicability; +use rustc_hir::def_id::DefId; use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, QPath}; use rustc_lint::{LateContext, LateLintPass, LintContext}; use rustc_middle::lint::in_external_macro; @@ -12,6 +13,8 @@ use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::source_map::Span; use rustc_span::symbol::sym; +use clippy_utils::is_diagnostic_assoc_item; + declare_clippy_lint! { /// **What it does:** Checks for `mem::replace()` on an `Option` with /// `None`. @@ -194,13 +197,44 @@ fn check_replace_with_uninit(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<' } } +/// Returns true if the `def_id` associated with the `path` is recognized as a "default-equivalent" +/// constructor from the std library +fn is_default_equivalent_ctor(cx: &LateContext<'_>, def_id: DefId, path: &QPath<'_>) -> bool { + let std_types_symbols = &[ + sym::string_type, + sym::vec_type, + sym::vecdeque_type, + sym::LinkedList, + sym::hashmap_type, + sym::BTreeMap, + sym::hashset_type, + sym::BTreeSet, + sym::BinaryHeap, + ]; + + if std_types_symbols + .iter() + .any(|symbol| is_diagnostic_assoc_item(cx, def_id, *symbol)) + { + if let QPath::TypeRelative(_, ref method) = path { + if method.ident.name == sym::new { + return true; + } + } + } + + false +} + fn check_replace_with_default(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) { if let ExprKind::Call(ref repl_func, _) = src.kind { if_chain! { if !in_external_macro(cx.tcx.sess, expr_span); if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind; if let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id(); - if match_def_path(cx, repl_def_id, &paths::DEFAULT_TRAIT_METHOD); + if is_diagnostic_assoc_item(cx, repl_def_id, sym::Default) + || is_default_equivalent_ctor(cx, repl_def_id, repl_func_qpath); + then { span_lint_and_then( cx, diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs index e17af49f6185..045123ab71e9 100644 --- a/clippy_utils/src/lib.rs +++ b/clippy_utils/src/lib.rs @@ -279,7 +279,7 @@ pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) trt_id.map_or(false, |trt_id| match_def_path(cx, trt_id, path)) } -/// Checks if the method call given in `expr` belongs to a trait or other container with a given +/// Checks if the method call given in `def_id` belongs to a trait or other container with a given /// diagnostic item pub fn is_diagnostic_assoc_item(cx: &LateContext<'_>, def_id: DefId, diag_item: Symbol) -> bool { cx.tcx diff --git a/tests/ui/mem_replace.fixed b/tests/ui/mem_replace.fixed index 54e962e7116e..3b6224254a0a 100644 --- a/tests/ui/mem_replace.fixed +++ b/tests/ui/mem_replace.fixed @@ -7,6 +7,7 @@ clippy::mem_replace_with_default )] +use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque}; use std::mem; fn replace_option_with_none() { @@ -19,9 +20,37 @@ fn replace_option_with_none() { fn replace_with_default() { let mut s = String::from("foo"); let _ = std::mem::take(&mut s); + let s = &mut String::from("foo"); let _ = std::mem::take(s); let _ = std::mem::take(s); + + let mut v = vec![123]; + let _ = std::mem::take(&mut v); + let _ = std::mem::take(&mut v); + let _ = std::mem::take(&mut v); + let _ = std::mem::take(&mut v); + + let mut hash_map: HashMap = HashMap::new(); + let _ = std::mem::take(&mut hash_map); + + let mut btree_map: BTreeMap = BTreeMap::new(); + let _ = std::mem::take(&mut btree_map); + + let mut vd: VecDeque = VecDeque::new(); + let _ = std::mem::take(&mut vd); + + let mut hash_set: HashSet<&str> = HashSet::new(); + let _ = std::mem::take(&mut hash_set); + + let mut btree_set: BTreeSet<&str> = BTreeSet::new(); + let _ = std::mem::take(&mut btree_set); + + let mut list: LinkedList = LinkedList::new(); + let _ = std::mem::take(&mut list); + + let mut binary_heap: BinaryHeap = BinaryHeap::new(); + let _ = std::mem::take(&mut binary_heap); } fn main() { diff --git a/tests/ui/mem_replace.rs b/tests/ui/mem_replace.rs index 60f527810716..0a36db9e9215 100644 --- a/tests/ui/mem_replace.rs +++ b/tests/ui/mem_replace.rs @@ -7,6 +7,7 @@ clippy::mem_replace_with_default )] +use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque}; use std::mem; fn replace_option_with_none() { @@ -19,9 +20,37 @@ fn replace_option_with_none() { fn replace_with_default() { let mut s = String::from("foo"); let _ = std::mem::replace(&mut s, String::default()); + let s = &mut String::from("foo"); let _ = std::mem::replace(s, String::default()); let _ = std::mem::replace(s, Default::default()); + + let mut v = vec![123]; + let _ = std::mem::replace(&mut v, Vec::default()); + let _ = std::mem::replace(&mut v, Default::default()); + let _ = std::mem::replace(&mut v, Vec::new()); + let _ = std::mem::replace(&mut v, vec![]); + + let mut hash_map: HashMap = HashMap::new(); + let _ = std::mem::replace(&mut hash_map, HashMap::new()); + + let mut btree_map: BTreeMap = BTreeMap::new(); + let _ = std::mem::replace(&mut btree_map, BTreeMap::new()); + + let mut vd: VecDeque = VecDeque::new(); + let _ = std::mem::replace(&mut vd, VecDeque::new()); + + let mut hash_set: HashSet<&str> = HashSet::new(); + let _ = std::mem::replace(&mut hash_set, HashSet::new()); + + let mut btree_set: BTreeSet<&str> = BTreeSet::new(); + let _ = std::mem::replace(&mut btree_set, BTreeSet::new()); + + let mut list: LinkedList = LinkedList::new(); + let _ = std::mem::replace(&mut list, LinkedList::new()); + + let mut binary_heap: BinaryHeap = BinaryHeap::new(); + let _ = std::mem::replace(&mut binary_heap, BinaryHeap::new()); } fn main() { diff --git a/tests/ui/mem_replace.stderr b/tests/ui/mem_replace.stderr index 245d33aa4f26..f8aa1538bffa 100644 --- a/tests/ui/mem_replace.stderr +++ b/tests/ui/mem_replace.stderr @@ -1,5 +1,5 @@ error: replacing an `Option` with `None` - --> $DIR/mem_replace.rs:14:13 + --> $DIR/mem_replace.rs:15:13 | LL | let _ = mem::replace(&mut an_option, None); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `an_option.take()` @@ -7,13 +7,13 @@ LL | let _ = mem::replace(&mut an_option, None); = note: `-D clippy::mem-replace-option-with-none` implied by `-D warnings` error: replacing an `Option` with `None` - --> $DIR/mem_replace.rs:16:13 + --> $DIR/mem_replace.rs:17:13 | LL | let _ = mem::replace(an_option, None); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `an_option.take()` error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` - --> $DIR/mem_replace.rs:21:13 + --> $DIR/mem_replace.rs:22:13 | LL | let _ = std::mem::replace(&mut s, String::default()); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut s)` @@ -21,16 +21,82 @@ LL | let _ = std::mem::replace(&mut s, String::default()); = note: `-D clippy::mem-replace-with-default` implied by `-D warnings` error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` - --> $DIR/mem_replace.rs:23:13 + --> $DIR/mem_replace.rs:25:13 | LL | let _ = std::mem::replace(s, String::default()); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(s)` error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` - --> $DIR/mem_replace.rs:24:13 + --> $DIR/mem_replace.rs:26:13 | LL | let _ = std::mem::replace(s, Default::default()); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(s)` -error: aborting due to 5 previous errors +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:29:13 + | +LL | let _ = std::mem::replace(&mut v, Vec::default()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut v)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:30:13 + | +LL | let _ = std::mem::replace(&mut v, Default::default()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut v)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:31:13 + | +LL | let _ = std::mem::replace(&mut v, Vec::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut v)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:32:13 + | +LL | let _ = std::mem::replace(&mut v, vec![]); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut v)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:35:13 + | +LL | let _ = std::mem::replace(&mut hash_map, HashMap::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut hash_map)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:38:13 + | +LL | let _ = std::mem::replace(&mut btree_map, BTreeMap::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut btree_map)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:41:13 + | +LL | let _ = std::mem::replace(&mut vd, VecDeque::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut vd)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:44:13 + | +LL | let _ = std::mem::replace(&mut hash_set, HashSet::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut hash_set)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:47:13 + | +LL | let _ = std::mem::replace(&mut btree_set, BTreeSet::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut btree_set)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:50:13 + | +LL | let _ = std::mem::replace(&mut list, LinkedList::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut list)` + +error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take` + --> $DIR/mem_replace.rs:53:13 + | +LL | let _ = std::mem::replace(&mut binary_heap, BinaryHeap::new()); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut binary_heap)` + +error: aborting due to 16 previous errors