use std::cmp;
-use crate::utils::{in_macro, is_copy, is_self_ty, snippet, span_lint_and_sugg};
+use crate::utils::{is_copy, is_self_ty, snippet, span_lint_and_sugg};
use if_chain::if_chain;
use matches::matches;
use rustc::hir;
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc::session::config::Config as SessionConfig;
-use rustc::ty::{self, FnSig};
-use rustc::{declare_tool_lint, lint_array};
+use rustc::ty;
+use rustc::{declare_tool_lint, impl_lint_pass};
use rustc_errors::Applicability;
use rustc_target::abi::LayoutOf;
use rustc_target::spec::abi::Abi;
-use syntax::ast::NodeId;
use syntax_pos::Span;
-/// **What it does:** Checks for functions taking arguments by reference, where
-/// the argument type is `Copy` and small enough to be more efficient to always
-/// pass by value.
-///
-/// **Why is this bad?** In many calling conventions instances of structs will
-/// be passed through registers if they fit into two or less general purpose
-/// registers.
-///
-/// **Known problems:** This lint is target register size dependent, it is
-/// limited to 32-bit to try and reduce portability problems between 32 and
-/// 64-bit, but if you are compiling for 8 or 16-bit targets then the limit
-/// will be different.
-///
-/// The configuration option `trivial_copy_size_limit` can be set to override
-/// this limit for a project.
-///
-/// This lint attempts to allow passing arguments by reference if a reference
-/// to that argument is returned. This is implemented by comparing the lifetime
-/// of the argument and return value for equality. However, this can cause
-/// false positives in cases involving multiple lifetimes that are bounded by
-/// each other.
-///
-/// **Example:**
-/// ```rust
-/// fn foo(v: &u32) {
-/// assert_eq!(v, 42);
-/// }
-/// // should be
-/// fn foo(v: u32) {
-/// assert_eq!(v, 42);
-/// }
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for functions taking arguments by reference, where
+ /// the argument type is `Copy` and small enough to be more efficient to always
+ /// pass by value.
+ ///
+ /// **Why is this bad?** In many calling conventions instances of structs will
+ /// be passed through registers if they fit into two or less general purpose
+ /// registers.
+ ///
+ /// **Known problems:** This lint is target register size dependent, it is
+ /// limited to 32-bit to try and reduce portability problems between 32 and
+ /// 64-bit, but if you are compiling for 8 or 16-bit targets then the limit
+ /// will be different.
+ ///
+ /// The configuration option `trivial_copy_size_limit` can be set to override
+ /// this limit for a project.
+ ///
+ /// This lint attempts to allow passing arguments by reference if a reference
+ /// to that argument is returned. This is implemented by comparing the lifetime
+ /// of the argument and return value for equality. However, this can cause
+ /// false positives in cases involving multiple lifetimes that are bounded by
+ /// each other.
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// // Bad
+ /// fn foo(v: &u32) {}
+ /// ```
+ ///
+ /// ```rust
+ /// // Better
+ /// fn foo(v: u32) {}
+ /// ```
pub TRIVIALLY_COPY_PASS_BY_REF,
perf,
"functions taking small copyable arguments by reference"
}
+#[derive(Copy, Clone)]
pub struct TriviallyCopyPassByRef {
limit: u64,
}
// Cap the calculated bit width at 32-bits to reduce
// portability problems between 32 and 64-bit targets
let bit_width = cmp::min(bit_width, 32);
+ #[allow(clippy::integer_division)]
let byte_width = bit_width / 8;
- // Use a limit of 2 times the register bit width
+ // Use a limit of 2 times the register byte width
byte_width * 2
});
Self { limit }
}
- fn check_trait_method(&mut self, cx: &LateContext<'_, 'tcx>, item: &TraitItemRef) {
- let method_def_id = cx.tcx.hir().local_def_id(item.id.node_id);
- let method_sig = cx.tcx.fn_sig(method_def_id);
- let method_sig = cx.tcx.erase_late_bound_regions(&method_sig);
+ fn check_poly_fn(&mut self, cx: &LateContext<'_, 'tcx>, hir_id: HirId, decl: &FnDecl, span: Option<Span>) {
+ let fn_def_id = cx.tcx.hir().local_def_id(hir_id);
- let decl = match cx.tcx.hir().fn_decl(item.id.node_id) {
- Some(b) => b,
- None => return,
- };
-
- self.check_poly_fn(cx, &decl, &method_sig, None);
- }
+ let fn_sig = cx.tcx.fn_sig(fn_def_id);
+ let fn_sig = cx.tcx.erase_late_bound_regions(&fn_sig);
- fn check_poly_fn(&mut self, cx: &LateContext<'_, 'tcx>, decl: &FnDecl, sig: &FnSig<'tcx>, span: Option<Span>) {
// Use lifetimes to determine if we're returning a reference to the
// argument. In that case we can't switch to pass-by-value as the
// argument will not live long enough.
- let output_lts = match sig.output().sty {
+ let output_lts = match fn_sig.output().kind {
ty::Ref(output_lt, _, _) => vec![output_lt],
ty::Adt(_, substs) => substs.regions().collect(),
_ => vec![],
};
- for (input, &ty) in decl.inputs.iter().zip(sig.inputs()) {
+ for (input, &ty) in decl.inputs.iter().zip(fn_sig.inputs()) {
// All spans generated from a proc-macro invocation are the same...
match span {
Some(s) if s == input.span => return,
}
if_chain! {
- if let ty::Ref(input_lt, ty, Mutability::MutImmutable) = ty.sty;
+ if let ty::Ref(input_lt, ty, Mutability::Immutable) = ty.kind;
if !output_lts.contains(&input_lt);
if is_copy(cx, ty);
if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes());
if size <= self.limit;
- if let hir::TyKind::Rptr(_, MutTy { ty: ref decl_ty, .. }) = input.node;
+ if let hir::TyKind::Rptr(_, MutTy { ty: ref decl_ty, .. }) = input.kind;
then {
let value_type = if is_self_ty(decl_ty) {
"self".into()
cx,
TRIVIALLY_COPY_PASS_BY_REF,
input.span,
- "this argument is passed by reference, but would be more efficient if passed by value",
+ &format!("this argument ({} byte) is passed by reference, but would be more efficient if passed by value (limit: {} byte)", size, self.limit),
"consider passing by value instead",
value_type,
Applicability::Unspecified,
}
}
}
-
- fn check_trait_items(&mut self, cx: &LateContext<'_, '_>, trait_items: &[TraitItemRef]) {
- for item in trait_items {
- if let AssociatedItemKind::Method { .. } = item.kind {
- self.check_trait_method(cx, item);
- }
- }
- }
}
-impl LintPass for TriviallyCopyPassByRef {
- fn get_lints(&self) -> LintArray {
- lint_array![TRIVIALLY_COPY_PASS_BY_REF]
- }
-
- fn name(&self) -> &'static str {
- "TrivallyCopyPassByRef"
- }
-}
+impl_lint_pass!(TriviallyCopyPassByRef => [TRIVIALLY_COPY_PASS_BY_REF]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TriviallyCopyPassByRef {
- fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
- if in_macro(item.span) {
+ fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
+ if item.span.from_expansion() {
return;
}
- if let ItemKind::Trait(_, _, _, _, ref trait_items) = item.node {
- self.check_trait_items(cx, trait_items);
+
+ if let hir::TraitItemKind::Method(method_sig, _) = &item.kind {
+ self.check_poly_fn(cx, item.hir_id, &*method_sig.decl, None);
}
}
decl: &'tcx FnDecl,
_body: &'tcx Body,
span: Span,
- node_id: NodeId,
+ hir_id: HirId,
) {
- if in_macro(span) {
+ if span.from_expansion() {
return;
}
return;
}
for a in attrs {
- if a.meta_item_list().is_some() && a.name() == "proc_macro_derive" {
+ if a.meta_item_list().is_some() && a.check_name(sym!(proc_macro_derive)) {
return;
}
}
}
// Exclude non-inherent impls
- if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(node_id)) {
- if matches!(item.node, ItemKind::Impl(_, _, _, _, Some(_), _, _) |
+ if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(hir_id)) {
+ if matches!(item.kind, ItemKind::Impl(_, _, _, _, Some(_), _, _) |
ItemKind::Trait(..))
{
return;
}
}
- let fn_def_id = cx.tcx.hir().local_def_id(node_id);
-
- let fn_sig = cx.tcx.fn_sig(fn_def_id);
- let fn_sig = cx.tcx.erase_late_bound_regions(&fn_sig);
-
- self.check_poly_fn(cx, decl, &fn_sig, Some(span));
+ self.check_poly_fn(cx, hir_id, decl, Some(span));
}
}
projects / rust.git / blobdiff