X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fmem_replace.rs;h=426c108d89fb59c2d5240e3c931ab7ea9efe5051;hb=b094bb1bd7f1cc702823c91ca509f338fedee24a;hp=3ae5863d69916eee4cdda420b738eb5b4ffce6ca;hpb=ce1c6b285dd41c5861bf3df9423c01b4a3232be4;p=rust.git diff --git a/clippy_lints/src/mem_replace.rs b/clippy_lints/src/mem_replace.rs index 3ae5863d699..426c108d89f 100644 --- a/clippy_lints/src/mem_replace.rs +++ b/clippy_lints/src/mem_replace.rs @@ -1,14 +1,17 @@ -use crate::utils::{ - in_macro, match_def_path, match_qpath, paths, snippet, snippet_with_applicability, span_help_and_lint, - span_lint_and_sugg, span_lint_and_then, -}; +use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg, span_lint_and_then}; +use clippy_utils::is_diagnostic_assoc_item; +use clippy_utils::source::{snippet, snippet_with_applicability}; +use clippy_utils::{in_macro, match_def_path, match_qpath, meets_msrv, paths}; use if_chain::if_chain; -use rustc::lint::in_external_macro; use rustc_errors::Applicability; +use rustc_hir::def_id::DefId; use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, QPath}; -use rustc_lint::{LateContext, LateLintPass}; -use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_lint::{LateContext, LateLintPass, LintContext}; +use rustc_middle::lint::in_external_macro; +use rustc_semver::RustcVersion; +use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::source_map::Span; +use rustc_span::symbol::sym; declare_clippy_lint! { /// **What it does:** Checks for `mem::replace()` on an `Option` with @@ -93,10 +96,10 @@ "replacing a value of type `T` with `T::default()` instead of using `std::mem::take`" } -declare_lint_pass!(MemReplace => +impl_lint_pass!(MemReplace => [MEM_REPLACE_OPTION_WITH_NONE, MEM_REPLACE_WITH_UNINIT, MEM_REPLACE_WITH_DEFAULT]); -fn check_replace_option_with_none(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) { +fn check_replace_option_with_none(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) { if let ExprKind::Path(ref replacement_qpath) = src.kind { // Check that second argument is `Option::None` if match_qpath(replacement_qpath, &paths::OPTION_NONE) { @@ -134,54 +137,113 @@ fn check_replace_option_with_none(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest } } -fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr<'_>, expr_span: Span) { - if let ExprKind::Call(ref repl_func, ref repl_args) = src.kind { - if_chain! { - if repl_args.is_empty(); - if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind; - if let Some(repl_def_id) = cx.tables.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id(); - then { - if match_def_path(cx, repl_def_id, &paths::MEM_UNINITIALIZED) { - span_help_and_lint( - cx, - MEM_REPLACE_WITH_UNINIT, - expr_span, - "replacing with `mem::uninitialized()`", - "consider using the `take_mut` crate instead", - ); - } else if match_def_path(cx, repl_def_id, &paths::MEM_ZEROED) && - !cx.tables.expr_ty(src).is_primitive() { - span_help_and_lint( - cx, - MEM_REPLACE_WITH_UNINIT, - expr_span, - "replacing with `mem::zeroed()`", - "consider using a default value or the `take_mut` crate instead", - ); - } +fn check_replace_with_uninit(cx: &LateContext<'_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) { + if_chain! { + // check if replacement is mem::MaybeUninit::uninit().assume_init() + if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(src.hir_id); + if cx.tcx.is_diagnostic_item(sym::assume_init, method_def_id); + then { + let mut applicability = Applicability::MachineApplicable; + span_lint_and_sugg( + cx, + MEM_REPLACE_WITH_UNINIT, + expr_span, + "replacing with `mem::MaybeUninit::uninit().assume_init()`", + "consider using", + format!( + "std::ptr::read({})", + snippet_with_applicability(cx, dest.span, "", &mut applicability) + ), + applicability, + ); + return; + } + } + + if_chain! { + if let ExprKind::Call(ref repl_func, ref repl_args) = src.kind; + if repl_args.is_empty(); + 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(); + then { + if cx.tcx.is_diagnostic_item(sym::mem_uninitialized, repl_def_id) { + let mut applicability = Applicability::MachineApplicable; + span_lint_and_sugg( + cx, + MEM_REPLACE_WITH_UNINIT, + expr_span, + "replacing with `mem::uninitialized()`", + "consider using", + format!( + "std::ptr::read({})", + snippet_with_applicability(cx, dest.span, "", &mut applicability) + ), + applicability, + ); + } else if cx.tcx.is_diagnostic_item(sym::mem_zeroed, repl_def_id) && + !cx.typeck_results().expr_ty(src).is_primitive() { + span_lint_and_help( + cx, + MEM_REPLACE_WITH_UNINIT, + expr_span, + "replacing with `mem::zeroed()`", + None, + "consider using a default value or the `take_mut` crate instead", + ); + } + } + } +} + +/// 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) { +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.tables.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 let Some(repl_def_id) = cx.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id(); + 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, MEM_REPLACE_WITH_DEFAULT, expr_span, "replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`", - |db| { + |diag| { if !in_macro(expr_span) { let suggestion = format!("std::mem::take({})", snippet(cx, dest.span, "")); - db.span_suggestion( + diag.span_suggestion( expr_span, "consider using", suggestion, @@ -195,20 +257,36 @@ fn check_replace_with_default(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest: &E } } -impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MemReplace { - fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) { +const MEM_REPLACE_WITH_DEFAULT_MSRV: RustcVersion = RustcVersion::new(1, 40, 0); + +pub struct MemReplace { + msrv: Option, +} + +impl MemReplace { + #[must_use] + pub fn new(msrv: Option) -> Self { + Self { msrv } + } +} + +impl<'tcx> LateLintPass<'tcx> for MemReplace { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { if_chain! { // Check that `expr` is a call to `mem::replace()` if let ExprKind::Call(ref func, ref func_args) = expr.kind; if let ExprKind::Path(ref func_qpath) = func.kind; - if let Some(def_id) = cx.tables.qpath_res(func_qpath, func.hir_id).opt_def_id(); + if let Some(def_id) = cx.qpath_res(func_qpath, func.hir_id).opt_def_id(); if match_def_path(cx, def_id, &paths::MEM_REPLACE); if let [dest, src] = &**func_args; then { check_replace_option_with_none(cx, src, dest, expr.span); - check_replace_with_uninit(cx, src, expr.span); - check_replace_with_default(cx, src, dest, expr.span); + check_replace_with_uninit(cx, src, dest, expr.span); + if meets_msrv(self.msrv.as_ref(), &MEM_REPLACE_WITH_DEFAULT_MSRV) { + check_replace_with_default(cx, src, dest, expr.span); + } } } } + extract_msrv_attr!(LateContext); }