Merge #3437
3437: issue #3318 Run trivially_copy_pass_by_ref for traits r=flip1995 a=waynr Addresses #3318 Co-authored-by: Wayne Warren <wayne.warren.s@gmail.com> Co-authored-by: Philipp Krones <hello@philkrones.com>
This commit is contained in:
bors[bot]
commit
1d5108c264
@ -18,12 +18,13 @@ use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use if_chain::if_chain;
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use crate::rustc::ty::TyKind;
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use crate::rustc::ty::FnSig;
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use crate::rustc::session::config::Config as SessionConfig;
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use crate::rustc_target::spec::abi::Abi;
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use crate::rustc_target::abi::LayoutOf;
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use crate::syntax::ast::NodeId;
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use crate::syntax_pos::Span;
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use crate::utils::{in_macro, is_copy, is_self, span_lint_and_sugg, snippet};
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use crate::utils::{in_macro, is_copy, is_self_ty, span_lint_and_sugg, snippet};
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/// **What it does:** Checks for functions taking arguments by reference, where
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/// the argument type is `Copy` and small enough to be more efficient to always
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@ -67,7 +68,7 @@ pub struct TriviallyCopyPassByRef {
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limit: u64,
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}
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impl TriviallyCopyPassByRef {
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impl<'a, 'tcx> TriviallyCopyPassByRef {
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pub fn new(limit: Option<u64>, target: &SessionConfig) -> Self {
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let limit = limit.unwrap_or_else(|| {
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let bit_width = target.usize_ty.bit_width().expect("usize should have a width") as u64;
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@ -80,6 +81,83 @@ impl TriviallyCopyPassByRef {
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});
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Self { limit }
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}
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fn check_trait_method(
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&mut self,
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cx: &LateContext<'_, 'tcx>,
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item: &TraitItemRef
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) {
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let method_def_id = cx.tcx.hir.local_def_id(item.id.node_id);
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let method_sig = cx.tcx.fn_sig(method_def_id);
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let method_sig = cx.tcx.erase_late_bound_regions(&method_sig);
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let decl = match cx.tcx.hir.fn_decl(item.id.node_id) {
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Some(b) => b,
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None => return,
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};
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self.check_poly_fn(cx, &decl, &method_sig, None);
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}
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fn check_poly_fn(
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&mut self,
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cx: &LateContext<'_, 'tcx>,
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decl: &FnDecl,
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sig: &FnSig<'tcx>,
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span: Option<Span>,
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) {
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// Use lifetimes to determine if we're returning a reference to the
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// argument. In that case we can't switch to pass-by-value as the
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// argument will not live long enough.
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let output_lts = match sig.output().sty {
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TyKind::Ref(output_lt, _, _) => vec![output_lt],
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TyKind::Adt(_, substs) => substs.regions().collect(),
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_ => vec![],
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};
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for (input, &ty) in decl.inputs.iter().zip(sig.inputs()) {
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// All spans generated from a proc-macro invocation are the same...
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match span {
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Some(s) if s == input.span => return,
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_ => (),
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}
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if_chain! {
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if let TyKind::Ref(input_lt, ty, Mutability::MutImmutable) = ty.sty;
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if !output_lts.contains(&input_lt);
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if is_copy(cx, ty);
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if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes());
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if size <= self.limit;
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if let hir::TyKind::Rptr(_, MutTy { ty: ref decl_ty, .. }) = input.node;
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then {
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let value_type = if is_self_ty(decl_ty) {
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"self".into()
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} else {
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snippet(cx, decl_ty.span, "_").into()
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};
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span_lint_and_sugg(
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cx,
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TRIVIALLY_COPY_PASS_BY_REF,
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input.span,
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"this argument is passed by reference, but would be more efficient if passed by value",
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"consider passing by value instead",
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value_type);
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}
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}
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}
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}
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fn check_trait_items(
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&mut self,
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cx: &LateContext<'_, '_>,
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trait_items: &[TraitItemRef]
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) {
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for item in trait_items {
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if let AssociatedItemKind::Method{..} = item.kind {
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self.check_trait_method(cx, item);
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}
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}
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}
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}
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impl LintPass for TriviallyCopyPassByRef {
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@ -89,12 +167,21 @@ impl LintPass for TriviallyCopyPassByRef {
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TriviallyCopyPassByRef {
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fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
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if in_macro(item.span) {
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return;
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}
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if let ItemKind::Trait(_, _, _, _, ref trait_items) = item.node {
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self.check_trait_items(cx, trait_items);
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}
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}
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fn check_fn(
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&mut self,
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cx: &LateContext<'a, 'tcx>,
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kind: FnKind<'tcx>,
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decl: &'tcx FnDecl,
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body: &'tcx Body,
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_body: &'tcx Body,
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span: Span,
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node_id: NodeId,
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) {
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@ -131,43 +218,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TriviallyCopyPassByRef {
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let fn_sig = cx.tcx.fn_sig(fn_def_id);
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let fn_sig = cx.tcx.erase_late_bound_regions(&fn_sig);
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// Use lifetimes to determine if we're returning a reference to the
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// argument. In that case we can't switch to pass-by-value as the
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// argument will not live long enough.
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let output_lts = match fn_sig.output().sty {
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TyKind::Ref(output_lt, _, _) => vec![output_lt],
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TyKind::Adt(_, substs) => substs.regions().collect(),
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_ => vec![],
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};
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for ((input, &ty), arg) in decl.inputs.iter().zip(fn_sig.inputs()).zip(&body.arguments) {
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// All spans generated from a proc-macro invocation are the same...
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if span == input.span {
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return;
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}
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if_chain! {
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if let TyKind::Ref(input_lt, ty, Mutability::MutImmutable) = ty.sty;
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if !output_lts.contains(&input_lt);
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if is_copy(cx, ty);
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if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes());
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if size <= self.limit;
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if let hir::TyKind::Rptr(_, MutTy { ty: ref decl_ty, .. }) = input.node;
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then {
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let value_type = if is_self(arg) {
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"self".into()
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} else {
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snippet(cx, decl_ty.span, "_").into()
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};
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span_lint_and_sugg(
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cx,
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TRIVIALLY_COPY_PASS_BY_REF,
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input.span,
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"this argument is passed by reference, but would be more efficient if passed by value",
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"consider passing by value instead",
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value_type);
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}
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}
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}
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self.check_poly_fn(cx, decl, &fn_sig, Some(span));
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}
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}
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@ -18,6 +18,11 @@ struct Foo(u32);
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#[derive(Copy, Clone)]
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struct Bar([u8; 24]);
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#[derive(Copy, Clone)]
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pub struct Color {
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pub r: u8, pub g: u8, pub b: u8, pub a: u8,
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}
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struct FooRef<'a> {
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foo: &'a Foo,
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}
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@ -80,6 +85,20 @@ impl Bar {
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}
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}
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trait MyTrait {
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fn trait_method(&self, _foo: &Foo);
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}
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pub trait MyTrait2 {
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fn trait_method2(&self, _color: &Color);
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}
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impl MyTrait for Foo {
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fn trait_method(&self, _foo: &Foo) {
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unimplemented!()
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}
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}
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fn main() {
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let (mut foo, bar) = (Foo(0), Bar([0; 24]));
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let (mut a, b, c, x, y, z) = (0, 0, Bar([0; 24]), 0, Foo(0), 0);
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@ -1,82 +1,94 @@
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:52:11
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--> $DIR/trivially_copy_pass_by_ref.rs:57:11
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52 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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57 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `u32`
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= note: `-D clippy::trivially-copy-pass-by-ref` implied by `-D warnings`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:52:20
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--> $DIR/trivially_copy_pass_by_ref.rs:57:20
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52 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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57 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Foo`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:52:29
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--> $DIR/trivially_copy_pass_by_ref.rs:57:29
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52 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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57 | fn bad(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Baz`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:62:12
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--> $DIR/trivially_copy_pass_by_ref.rs:67:12
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62 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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67 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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| ^^^^^ help: consider passing by value instead: `self`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:62:22
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--> $DIR/trivially_copy_pass_by_ref.rs:67:22
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62 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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67 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `u32`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:62:31
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--> $DIR/trivially_copy_pass_by_ref.rs:67:31
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62 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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67 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Foo`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:62:40
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--> $DIR/trivially_copy_pass_by_ref.rs:67:40
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62 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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67 | fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Baz`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:65:16
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--> $DIR/trivially_copy_pass_by_ref.rs:70:16
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65 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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70 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `u32`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:65:25
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--> $DIR/trivially_copy_pass_by_ref.rs:70:25
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65 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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70 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Foo`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:65:34
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--> $DIR/trivially_copy_pass_by_ref.rs:70:34
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65 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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70 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Baz`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:79:16
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--> $DIR/trivially_copy_pass_by_ref.rs:84:16
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79 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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84 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `u32`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:79:25
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--> $DIR/trivially_copy_pass_by_ref.rs:84:25
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79 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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84 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Foo`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:79:34
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--> $DIR/trivially_copy_pass_by_ref.rs:84:34
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79 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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84 | fn bad2(x: &u32, y: &Foo, z: &Baz) {
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| ^^^^ help: consider passing by value instead: `Baz`
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error: aborting due to 13 previous errors
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:89:34
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89 | fn trait_method(&self, _foo: &Foo);
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| ^^^^ help: consider passing by value instead: `Foo`
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error: this argument is passed by reference, but would be more efficient if passed by value
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--> $DIR/trivially_copy_pass_by_ref.rs:93:37
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93 | fn trait_method2(&self, _color: &Color);
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| ^^^^^^ help: consider passing by value instead: `Color`
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error: aborting due to 15 previous errors
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