]> git.lizzy.rs Git - rust.git/blobdiff - clippy_lints/src/needless_pass_by_value.rs
merge rustc history
[rust.git] / clippy_lints / src / needless_pass_by_value.rs
index a435f86bfd8d56af2f8892b53517127bbd622c7a..060037ed496910f714e114d130bf25b9f0af1f93 100644 (file)
@@ -1,18 +1,23 @@
-use crate::utils::ptr::get_spans;
-use crate::utils::{
-    get_trait_def_id, implements_trait, is_copy, is_self, is_type_diagnostic_item, multispan_sugg, paths, snippet,
-    snippet_opt, span_lint_and_then,
-};
+use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
+use clippy_utils::ptr::get_spans;
+use clippy_utils::source::{snippet, snippet_opt};
+use clippy_utils::ty::{implements_trait, is_copy, is_type_diagnostic_item};
+use clippy_utils::{get_trait_def_id, is_self, paths};
 use if_chain::if_chain;
 use rustc_ast::ast::Attribute;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_errors::{Applicability, DiagnosticBuilder};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{Applicability, Diagnostic};
 use rustc_hir::intravisit::FnKind;
-use rustc_hir::{BindingAnnotation, Body, FnDecl, GenericArg, HirId, ItemKind, Impl, Node, PatKind, QPath, TyKind};
+use rustc_hir::{
+    BindingAnnotation, Body, FnDecl, GenericArg, HirId, Impl, ItemKind, Mutability, Node, PatKind, QPath, TyKind,
+};
+use rustc_hir::{HirIdMap, HirIdSet};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::{self, TypeFoldable};
+use rustc_middle::mir::FakeReadCause;
+use rustc_middle::ty::{self, TypeVisitable};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::kw;
 use rustc_span::{sym, Span};
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::traits;
 use std::borrow::Cow;
 
 declare_clippy_lint! {
-    /// **What it does:** Checks for functions taking arguments by value, but not
+    /// ### What it does
+    /// Checks for functions taking arguments by value, but not
     /// consuming them in its
     /// body.
     ///
-    /// **Why is this bad?** Taking arguments by reference is more flexible and can
+    /// ### Why is this bad?
+    /// Taking arguments by reference is more flexible and can
     /// sometimes avoid
     /// unnecessary allocations.
     ///
-    /// **Known problems:**
+    /// ### Known problems
     /// * This lint suggests taking an argument by reference,
     /// however sometimes it is better to let users decide the argument type
     /// (by using `Borrow` trait, for example), depending on how the function is used.
     ///
-    /// **Example:**
+    /// ### Example
     /// ```rust
     /// fn foo(v: Vec<i32>) {
     ///     assert_eq!(v.len(), 42);
@@ -46,6 +53,7 @@
     ///     assert_eq!(v.len(), 42);
     /// }
     /// ```
+    #[clippy::version = "pre 1.29.0"]
     pub NEEDLESS_PASS_BY_VALUE,
     pedantic,
     "functions taking arguments by value, but not consuming them in its body"
@@ -64,7 +72,7 @@ macro_rules! need {
 }
 
 impl<'tcx> LateLintPass<'tcx> for NeedlessPassByValue {
-    #[allow(clippy::too_many_lines)]
+    #[expect(clippy::too_many_lines)]
     fn check_fn(
         &mut self,
         cx: &LateContext<'tcx>,
@@ -79,13 +87,14 @@ fn check_fn(
         }
 
         match kind {
-            FnKind::ItemFn(.., header, _, attrs) => {
+            FnKind::ItemFn(.., header) => {
+                let attrs = cx.tcx.hir().attrs(hir_id);
                 if header.abi != Abi::Rust || requires_exact_signature(attrs) {
                     return;
                 }
             },
             FnKind::Method(..) => (),
-            FnKind::Closure(..) => return,
+            FnKind::Closure => return,
         }
 
         // Exclude non-inherent impls
@@ -99,7 +108,6 @@ fn check_fn(
         }
 
         // Allow `Borrow` or functions to be taken by value
-        let borrow_trait = need!(get_trait_def_id(cx, &paths::BORROW_TRAIT));
         let allowed_traits = [
             need!(cx.tcx.lang_items().fn_trait()),
             need!(cx.tcx.lang_items().fn_once_trait()),
@@ -115,13 +123,9 @@ fn check_fn(
             .filter(|p| !p.is_global())
             .filter_map(|obligation| {
                 // Note that we do not want to deal with qualified predicates here.
-                if let ty::PredicateKind::Atom(ty::PredicateAtom::Trait(pred, _)) = obligation.predicate.kind() {
-                    if pred.def_id() == sized_trait {
-                        return None;
-                    }
-                    Some(pred)
-                } else {
-                    None
+                match obligation.predicate.kind().no_bound_vars() {
+                    Some(ty::PredicateKind::Trait(pred)) if pred.def_id() != sized_trait => Some(pred),
+                    _ => None,
                 }
             })
             .collect::<Vec<_>>();
@@ -153,7 +157,7 @@ fn check_fn(
             // Ignore `self`s.
             if idx == 0 {
                 if let PatKind::Binding(.., ident, _) = arg.pat.kind {
-                    if ident.as_str() == "self" {
+                    if ident.name == kw::SelfLower {
                         continue;
                     }
                 }
@@ -167,9 +171,9 @@ fn check_fn(
                 let preds = preds.iter().filter(|t| t.self_ty() == ty).collect::<Vec<_>>();
 
                 (
-                    preds.iter().any(|t| t.def_id() == borrow_trait),
+                    preds.iter().any(|t| cx.tcx.is_diagnostic_item(sym::Borrow, t.def_id())),
                     !preds.is_empty() && {
-                        let ty_empty_region = cx.tcx.mk_imm_ref(cx.tcx.lifetimes.re_root_empty, ty);
+                        let ty_empty_region = cx.tcx.mk_imm_ref(cx.tcx.lifetimes.re_erased, ty);
                         preds.iter().all(|t| {
                             let ty_params = t.trait_ref.substs.iter().skip(1).collect::<Vec<_>>();
                             implements_trait(cx, ty_empty_region, t.def_id(), &ty_params)
@@ -186,18 +190,19 @@ fn check_fn(
                 if !implements_borrow_trait;
                 if !all_borrowable_trait;
 
-                if let PatKind::Binding(mode, canonical_id, ..) = arg.pat.kind;
+                if let PatKind::Binding(BindingAnnotation(_, Mutability::Not), canonical_id, ..) = arg.pat.kind;
                 if !moved_vars.contains(&canonical_id);
                 then {
-                    if mode == BindingAnnotation::Mutable || mode == BindingAnnotation::RefMut {
-                        continue;
-                    }
-
                     // Dereference suggestion
-                    let sugg = |diag: &mut DiagnosticBuilder<'_>| {
+                    let sugg = |diag: &mut Diagnostic| {
                         if let ty::Adt(def, ..) = ty.kind() {
-                            if let Some(span) = cx.tcx.hir().span_if_local(def.did) {
-                                if can_type_implement_copy(cx.tcx, cx.param_env, ty).is_ok() {
+                            if let Some(span) = cx.tcx.hir().span_if_local(def.did()) {
+                                if can_type_implement_copy(
+                                    cx.tcx,
+                                    cx.param_env,
+                                    ty,
+                                    traits::ObligationCause::dummy_with_span(span),
+                                ).is_ok() {
                                     diag.span_help(span, "consider marking this type as `Copy`");
                                 }
                             }
@@ -205,10 +210,10 @@ fn check_fn(
 
                         let deref_span = spans_need_deref.get(&canonical_id);
                         if_chain! {
-                            if is_type_diagnostic_item(cx, ty, sym::vec_type);
+                            if is_type_diagnostic_item(cx, ty, sym::Vec);
                             if let Some(clone_spans) =
                                 get_spans(cx, Some(body.id()), idx, &[("clone", ".to_owned()")]);
-                            if let TyKind::Path(QPath::Resolved(_, ref path)) = input.kind;
+                            if let TyKind::Path(QPath::Resolved(_, path)) = input.kind;
                             if let Some(elem_ty) = path.segments.iter()
                                 .find(|seg| seg.ident.name == sym::Vec)
                                 .and_then(|ps| ps.args.as_ref())
@@ -228,12 +233,13 @@ fn check_fn(
                                 for (span, suggestion) in clone_spans {
                                     diag.span_suggestion(
                                         span,
-                                        &snippet_opt(cx, span)
+                                        snippet_opt(cx, span)
                                             .map_or(
                                                 "change the call to".into(),
                                                 |x| Cow::from(format!("change `{}` to", x)),
-                                            ),
-                                        suggestion.into(),
+                                            )
+                                            .as_ref(),
+                                        suggestion,
                                         Applicability::Unspecified,
                                     );
                                 }
@@ -244,25 +250,26 @@ fn check_fn(
                             }
                         }
 
-                        if is_type_diagnostic_item(cx, ty, sym::string_type) {
+                        if is_type_diagnostic_item(cx, ty, sym::String) {
                             if let Some(clone_spans) =
                                 get_spans(cx, Some(body.id()), idx, &[("clone", ".to_string()"), ("as_str", "")]) {
                                 diag.span_suggestion(
                                     input.span,
                                     "consider changing the type to",
-                                    "&str".to_string(),
+                                    "&str",
                                     Applicability::Unspecified,
                                 );
 
                                 for (span, suggestion) in clone_spans {
                                     diag.span_suggestion(
                                         span,
-                                        &snippet_opt(cx, span)
+                                        snippet_opt(cx, span)
                                             .map_or(
                                                 "change the call to".into(),
                                                 |x| Cow::from(format!("change `{}` to", x))
-                                            ),
-                                        suggestion.into(),
+                                            )
+                                            .as_ref(),
+                                        suggestion,
                                         Applicability::Unspecified,
                                     );
                                 }
@@ -279,7 +286,7 @@ fn check_fn(
                             spans.extend(
                                 deref_span
                                     .iter()
-                                    .cloned()
+                                    .copied()
                                     .map(|span| (span, format!("*{}", snippet(cx, span, "<expr>")))),
                             );
                             spans.sort_by_key(|&(span, _)| span);
@@ -311,10 +318,10 @@ fn requires_exact_signature(attrs: &[Attribute]) -> bool {
 
 #[derive(Default)]
 struct MovedVariablesCtxt {
-    moved_vars: FxHashSet<HirId>,
+    moved_vars: HirIdSet,
     /// Spans which need to be prefixed with `*` for dereferencing the
     /// suggested additional reference.
-    spans_need_deref: FxHashMap<HirId, FxHashSet<Span>>,
+    spans_need_deref: HirIdMap<FxHashSet<Span>>,
 }
 
 impl MovedVariablesCtxt {
@@ -326,13 +333,13 @@ fn move_common(&mut self, cmt: &euv::PlaceWithHirId<'_>) {
 }
 
 impl<'tcx> euv::Delegate<'tcx> for MovedVariablesCtxt {
-    fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _: HirId, mode: euv::ConsumeMode) {
-        if let euv::ConsumeMode::Move = mode {
-            self.move_common(cmt);
-        }
+    fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, _: HirId) {
+        self.move_common(cmt);
     }
 
     fn borrow(&mut self, _: &euv::PlaceWithHirId<'tcx>, _: HirId, _: ty::BorrowKind) {}
 
     fn mutate(&mut self, _: &euv::PlaceWithHirId<'tcx>, _: HirId) {}
+
+    fn fake_read(&mut self, _: &rustc_typeck::expr_use_visitor::PlaceWithHirId<'tcx>, _: FakeReadCause, _: HirId) {}
 }