use crate::utils::ptr::get_spans;
use crate::utils::{
- get_trait_def_id, implements_trait, in_macro, is_copy, is_self, match_type, multispan_sugg, paths, snippet,
- snippet_opt, span_lint_and_then,
+ get_trait_def_id, implements_trait, is_copy, is_self, is_type_diagnostic_item, match_type, multispan_sugg, paths,
+ snippet, snippet_opt, span_lint_and_then,
};
use if_chain::if_chain;
use matches::matches;
+use rustc::declare_lint_pass;
use rustc::hir::intravisit::FnKind;
use rustc::hir::*;
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::middle::expr_use_visitor as euv;
-use rustc::middle::mem_categorization as mc;
use rustc::traits;
use rustc::ty::{self, RegionKind, TypeFoldable};
-use rustc::{declare_tool_lint, lint_array};
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::Applicability;
+use rustc_session::declare_tool_lint;
use rustc_target::spec::abi::Abi;
+use rustc_typeck::expr_use_visitor as euv;
use std::borrow::Cow;
-use syntax::ast::NodeId;
+use syntax::ast::Attribute;
use syntax::errors::DiagnosticBuilder;
-use syntax_pos::Span;
-
-/// **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
-/// sometimes avoid
-/// unnecessary allocations.
-///
-/// **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:**
-/// ```rust
-/// fn foo(v: Vec<i32>) {
-/// assert_eq!(v.len(), 42);
-/// }
-/// // should be
-/// fn foo(v: &[i32]) {
-/// assert_eq!(v.len(), 42);
-/// }
-/// ```
+use syntax_pos::{Span, Symbol};
+
declare_clippy_lint! {
+ /// **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
+ /// sometimes avoid
+ /// unnecessary allocations.
+ ///
+ /// **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:**
+ /// ```rust
+ /// fn foo(v: Vec<i32>) {
+ /// assert_eq!(v.len(), 42);
+ /// }
+ /// ```
+ ///
+ /// ```rust
+ /// // should be
+ /// fn foo(v: &[i32]) {
+ /// assert_eq!(v.len(), 42);
+ /// }
+ /// ```
pub NEEDLESS_PASS_BY_VALUE,
pedantic,
"functions taking arguments by value, but not consuming them in its body"
}
-pub struct NeedlessPassByValue;
-
-impl LintPass for NeedlessPassByValue {
- fn get_lints(&self) -> LintArray {
- lint_array![NEEDLESS_PASS_BY_VALUE]
- }
-
- fn name(&self) -> &'static str {
- "NeedlessPassByValue"
- }
-}
+declare_lint_pass!(NeedlessPassByValue => [NEEDLESS_PASS_BY_VALUE]);
macro_rules! need {
($e: expr) => {
cx: &LateContext<'a, 'tcx>,
kind: FnKind<'tcx>,
decl: &'tcx FnDecl,
- body: &'tcx Body,
+ body: &'tcx Body<'_>,
span: Span,
- node_id: NodeId,
+ hir_id: HirId,
) {
- if in_macro(span) {
+ if span.from_expansion() {
return;
}
match kind {
FnKind::ItemFn(.., header, _, attrs) => {
- if header.abi != Abi::Rust {
+ if header.abi != Abi::Rust || requires_exact_signature(attrs) {
return;
}
- for a in attrs {
- if a.meta_item_list().is_some() && a.name() == "proc_macro_derive" {
- return;
- }
- }
},
FnKind::Method(..) => (),
_ => 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 sized_trait = need!(cx.tcx.lang_items().sized_trait());
- let fn_def_id = cx.tcx.hir().local_def_id(node_id);
+ let fn_def_id = cx.tcx.hir().local_def_id(hir_id);
let preds = traits::elaborate_predicates(cx.tcx, cx.param_env.caller_bounds.to_vec())
.filter(|p| !p.is_global())
spans_need_deref,
..
} = {
- let mut ctx = MovedVariablesCtxt::new(cx);
- let region_scope_tree = &cx.tcx.region_scope_tree(fn_def_id);
- euv::ExprUseVisitor::new(&mut ctx, cx.tcx, cx.param_env, region_scope_tree, cx.tables, None)
- .consume_body(body);
+ let mut ctx = MovedVariablesCtxt::default();
+ cx.tcx.infer_ctxt().enter(|infcx| {
+ euv::ExprUseVisitor::new(&mut ctx, &infcx, fn_def_id, cx.param_env, cx.tables).consume_body(body);
+ });
ctx
};
let fn_sig = cx.tcx.fn_sig(fn_def_id);
let fn_sig = cx.tcx.erase_late_bound_regions(&fn_sig);
- for (idx, ((input, &ty), arg)) in decl.inputs.iter().zip(fn_sig.inputs()).zip(&body.arguments).enumerate() {
+ for (idx, ((input, &ty), arg)) in decl.inputs.iter().zip(fn_sig.inputs()).zip(body.params).enumerate() {
// All spans generated from a proc-macro invocation are the same...
if span == input.span {
return;
// Ignore `self`s.
if idx == 0 {
- if let PatKind::Binding(_, _, ident, ..) = arg.pat.node {
+ if let PatKind::Binding(.., ident, _) = arg.pat.kind {
if ident.as_str() == "self" {
continue;
}
//
// * Exclude a type that is specifically bounded by `Borrow`.
- // * Exclude a type whose reference also fulfills its bound. (e.g. `std::convert::AsRef`,
+ // * Exclude a type whose reference also fulfills its bound. (e.g., `std::convert::AsRef`,
// `serde::Serialize`)
let (implements_borrow_trait, all_borrowable_trait) = {
let preds = preds
.skip(1)
.cloned()
.collect::<Vec<_>>();
- implements_trait(cx, cx.tcx.mk_imm_ref(&RegionKind::ReErased, ty), t.def_id(), ty_params)
+ implements_trait(cx, cx.tcx.mk_imm_ref(&RegionKind::ReEmpty, ty), t.def_id(), ty_params)
}),
)
};
if_chain! {
if !is_self(arg);
- if !ty.is_mutable_pointer();
+ if !ty.is_mutable_ptr();
if !is_copy(cx, ty);
if !whitelisted_traits.iter().any(|&t| implements_trait(cx, ty, t, &[]));
if !implements_borrow_trait;
if !all_borrowable_trait;
- if let PatKind::Binding(mode, canonical_id, ..) = arg.pat.node;
+ if let PatKind::Binding(mode, canonical_id, ..) = arg.pat.kind;
if !moved_vars.contains(&canonical_id);
then {
if mode == BindingAnnotation::Mutable || mode == BindingAnnotation::RefMut {
// Dereference suggestion
let sugg = |db: &mut DiagnosticBuilder<'_>| {
- if let ty::Adt(def, ..) = ty.sty {
+ if let ty::Adt(def, ..) = ty.kind {
if let Some(span) = cx.tcx.hir().span_if_local(def.did) {
if cx.param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
db.span_help(span, "consider marking this type as Copy");
let deref_span = spans_need_deref.get(&canonical_id);
if_chain! {
- if match_type(cx, ty, &paths::VEC);
+ if is_type_diagnostic_item(cx, ty, Symbol::intern("vec_type"));
if let Some(clone_spans) =
get_spans(cx, Some(body.id()), idx, &[("clone", ".to_owned()")]);
- if let TyKind::Path(QPath::Resolved(_, ref path)) = input.node;
+ if let TyKind::Path(QPath::Resolved(_, ref path)) = input.kind;
if let Some(elem_ty) = path.segments.iter()
- .find(|seg| seg.ident.name == "Vec")
+ .find(|seg| seg.ident.name == sym!(Vec))
.and_then(|ps| ps.args.as_ref())
.map(|params| params.args.iter().find_map(|arg| match arg {
GenericArg::Type(ty) => Some(ty),
- GenericArg::Lifetime(_) => None,
+ _ => None,
}).unwrap());
then {
let slice_ty = format!("&[{}]", snippet(cx, elem_ty.span, "_"));
}
}
-struct MovedVariablesCtxt<'a, 'tcx: 'a> {
- cx: &'a LateContext<'a, 'tcx>,
- moved_vars: FxHashSet<NodeId>,
+/// Functions marked with these attributes must have the exact signature.
+fn requires_exact_signature(attrs: &[Attribute]) -> bool {
+ attrs.iter().any(|attr| {
+ [sym!(proc_macro), sym!(proc_macro_attribute), sym!(proc_macro_derive)]
+ .iter()
+ .any(|&allow| attr.check_name(allow))
+ })
+}
+
+#[derive(Default)]
+struct MovedVariablesCtxt {
+ moved_vars: FxHashSet<HirId>,
/// Spans which need to be prefixed with `*` for dereferencing the
/// suggested additional reference.
- spans_need_deref: FxHashMap<NodeId, FxHashSet<Span>>,
+ spans_need_deref: FxHashMap<HirId, FxHashSet<Span>>,
}
-impl<'a, 'tcx> MovedVariablesCtxt<'a, 'tcx> {
- fn new(cx: &'a LateContext<'a, 'tcx>) -> Self {
- Self {
- cx,
- moved_vars: FxHashSet::default(),
- spans_need_deref: FxHashMap::default(),
- }
- }
-
- fn move_common(&mut self, _consume_id: NodeId, _span: Span, cmt: &mc::cmt_<'tcx>) {
- let cmt = unwrap_downcast_or_interior(cmt);
-
- if let mc::Categorization::Local(vid) = cmt.cat {
+impl MovedVariablesCtxt {
+ fn move_common(&mut self, cmt: &euv::Place<'_>) {
+ if let euv::PlaceBase::Local(vid) = cmt.base {
self.moved_vars.insert(vid);
}
}
-
- fn non_moving_pat(&mut self, matched_pat: &Pat, cmt: &mc::cmt_<'tcx>) {
- let cmt = unwrap_downcast_or_interior(cmt);
-
- if let mc::Categorization::Local(vid) = cmt.cat {
- let mut id = matched_pat.id;
- loop {
- let parent = self.cx.tcx.hir().get_parent_node(id);
- if id == parent {
- // no parent
- return;
- }
- id = parent;
-
- if let Some(node) = self.cx.tcx.hir().find(id) {
- match node {
- Node::Expr(e) => {
- // `match` and `if let`
- if let ExprKind::Match(ref c, ..) = e.node {
- self.spans_need_deref
- .entry(vid)
- .or_insert_with(FxHashSet::default)
- .insert(c.span);
- }
- },
-
- Node::Stmt(s) => {
- // `let <pat> = x;`
- if_chain! {
- if let StmtKind::Local(ref local) = s.node;
- then {
- self.spans_need_deref
- .entry(vid)
- .or_insert_with(FxHashSet::default)
- .insert(local.init
- .as_ref()
- .map(|e| e.span)
- .expect("`let` stmt without init aren't caught by match_pat"));
- }
- }
- },
-
- _ => {},
- }
- }
- }
- }
- }
}
-impl<'a, 'tcx> euv::Delegate<'tcx> for MovedVariablesCtxt<'a, 'tcx> {
- fn consume(&mut self, consume_id: NodeId, consume_span: Span, cmt: &mc::cmt_<'tcx>, mode: euv::ConsumeMode) {
- if let euv::ConsumeMode::Move(_) = mode {
- self.move_common(consume_id, consume_span, cmt);
+impl<'tcx> euv::Delegate<'tcx> for MovedVariablesCtxt {
+ fn consume(&mut self, cmt: &euv::Place<'tcx>, mode: euv::ConsumeMode) {
+ if let euv::ConsumeMode::Move = mode {
+ self.move_common(cmt);
}
}
- fn matched_pat(&mut self, matched_pat: &Pat, cmt: &mc::cmt_<'tcx>, mode: euv::MatchMode) {
- if let euv::MatchMode::MovingMatch = mode {
- self.move_common(matched_pat.id, matched_pat.span, cmt);
- } else {
- self.non_moving_pat(matched_pat, cmt);
- }
- }
-
- fn consume_pat(&mut self, consume_pat: &Pat, cmt: &mc::cmt_<'tcx>, mode: euv::ConsumeMode) {
- if let euv::ConsumeMode::Move(_) = mode {
- self.move_common(consume_pat.id, consume_pat.span, cmt);
- }
- }
+ fn borrow(&mut self, _: &euv::Place<'tcx>, _: ty::BorrowKind) {}
- fn borrow(
- &mut self,
- _: NodeId,
- _: Span,
- _: &mc::cmt_<'tcx>,
- _: ty::Region<'_>,
- _: ty::BorrowKind,
- _: euv::LoanCause,
- ) {
- }
-
- fn mutate(&mut self, _: NodeId, _: Span, _: &mc::cmt_<'tcx>, _: euv::MutateMode) {}
-
- fn decl_without_init(&mut self, _: NodeId, _: Span) {}
-}
-
-fn unwrap_downcast_or_interior<'a, 'tcx>(mut cmt: &'a mc::cmt_<'tcx>) -> mc::cmt_<'tcx> {
- loop {
- match cmt.cat {
- mc::Categorization::Downcast(ref c, _) | mc::Categorization::Interior(ref c, _) => {
- cmt = c;
- },
- _ => return (*cmt).clone(),
- }
- }
+ fn mutate(&mut self, _: &euv::Place<'tcx>) {}
}