mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-11-23 13:13:34 +00:00
emit lints in check_crate_post
for useless_vec
this fixes issue #11861 by adding an extra map to keep track of which spans are ok to lint
This commit is contained in:
parent
52deee2592
commit
884bec3d85
5 changed files with 163 additions and 71 deletions
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@ -50,6 +50,8 @@ extern crate clippy_utils;
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#[macro_use]
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extern crate declare_clippy_lint;
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use std::collections::BTreeMap;
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use rustc_data_structures::fx::FxHashSet;
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use rustc_lint::{Lint, LintId};
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@ -725,6 +727,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
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Box::new(vec::UselessVec {
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too_large_for_stack,
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msrv: msrv(),
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span_to_lint_map: BTreeMap::new(),
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})
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});
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store.register_late_pass(|_| Box::new(panic_unimplemented::PanicUnimplemented));
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@ -1,25 +1,27 @@
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use std::collections::BTreeMap;
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use std::ops::ControlFlow;
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use clippy_config::msrvs::{self, Msrv};
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use clippy_utils::consts::{constant, Constant};
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::diagnostics::span_lint_hir_and_then;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::is_copy;
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use clippy_utils::visitors::for_each_local_use_after_expr;
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use clippy_utils::{get_parent_expr, higher, is_trait_method};
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use rustc_errors::Applicability;
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use rustc_hir::{BorrowKind, Expr, ExprKind, Mutability, Node, PatKind};
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use rustc_hir::{BorrowKind, Expr, ExprKind, HirId, Mutability, Node, PatKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::layout::LayoutOf;
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use rustc_middle::ty::{self, Ty};
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use rustc_session::impl_lint_pass;
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use rustc_span::{sym, Span};
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use rustc_span::{sym, DesugaringKind, Span};
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#[expect(clippy::module_name_repetitions)]
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#[derive(Clone)]
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pub struct UselessVec {
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pub too_large_for_stack: u64,
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pub msrv: Msrv,
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pub span_to_lint_map: BTreeMap<Span, Option<(HirId, SuggestedType, String, Applicability)>>,
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}
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declare_clippy_lint! {
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@ -69,64 +71,88 @@ pub fn is_allowed_vec_method(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
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impl<'tcx> LateLintPass<'tcx> for UselessVec {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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// search for `&vec![_]` or `vec![_]` expressions where the adjusted type is `&[_]`
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if adjusts_to_slice(cx, expr)
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&& let Some(vec_args) = higher::VecArgs::hir(cx, expr.peel_borrows())
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{
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let (suggest_slice, span) = if let ExprKind::AddrOf(BorrowKind::Ref, mutability, _) = expr.kind {
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// `expr` is `&vec![_]`, so suggest `&[_]` (or `&mut[_]` resp.)
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(SuggestedType::SliceRef(mutability), expr.span)
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} else {
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// `expr` is the `vec![_]` expansion, so suggest `[_]`
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// and also use the span of the actual `vec![_]` expression
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(SuggestedType::Array, expr.span.ctxt().outer_expn_data().call_site)
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};
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if let Some(vec_args) = higher::VecArgs::hir(cx, expr.peel_borrows()) {
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// search for `let foo = vec![_]` expressions where all uses of `foo`
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// adjust to slices or call a method that exist on slices (e.g. len)
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if let Node::Local(local) = cx.tcx.hir().get_parent(expr.hir_id)
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// for now ignore locals with type annotations.
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// this is to avoid compile errors when doing the suggestion here: let _: Vec<_> = vec![..];
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&& local.ty.is_none()
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&& let PatKind::Binding(_, id, ..) = local.pat.kind
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&& is_copy(cx, vec_type(cx.typeck_results().expr_ty_adjusted(expr.peel_borrows())))
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{
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let only_slice_uses = for_each_local_use_after_expr(cx, id, expr.hir_id, |expr| {
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// allow indexing into a vec and some set of allowed method calls that exist on slices, too
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if let Some(parent) = get_parent_expr(cx, expr)
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&& (adjusts_to_slice(cx, expr)
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|| matches!(parent.kind, ExprKind::Index(..))
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|| is_allowed_vec_method(cx, parent))
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{
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ControlFlow::Continue(())
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} else {
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ControlFlow::Break(())
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}
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})
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.is_continue();
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self.check_vec_macro(cx, &vec_args, span, suggest_slice);
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}
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// search for `let foo = vec![_]` expressions where all uses of `foo`
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// adjust to slices or call a method that exist on slices (e.g. len)
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if let Some(vec_args) = higher::VecArgs::hir(cx, expr)
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&& let Node::Local(local) = cx.tcx.hir().get_parent(expr.hir_id)
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// for now ignore locals with type annotations.
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// this is to avoid compile errors when doing the suggestion here: let _: Vec<_> = vec![..];
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&& local.ty.is_none()
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&& let PatKind::Binding(_, id, ..) = local.pat.kind
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&& is_copy(cx, vec_type(cx.typeck_results().expr_ty_adjusted(expr)))
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{
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let only_slice_uses = for_each_local_use_after_expr(cx, id, expr.hir_id, |expr| {
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// allow indexing into a vec and some set of allowed method calls that exist on slices, too
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if let Some(parent) = get_parent_expr(cx, expr)
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&& (adjusts_to_slice(cx, expr)
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|| matches!(parent.kind, ExprKind::Index(..))
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|| is_allowed_vec_method(cx, parent))
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{
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ControlFlow::Continue(())
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let span = expr.span.ctxt().outer_expn_data().call_site;
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if only_slice_uses {
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self.check_vec_macro(cx, &vec_args, span, expr.hir_id, SuggestedType::Array);
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} else {
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ControlFlow::Break(())
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self.span_to_lint_map.insert(span, None);
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}
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})
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.is_continue();
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}
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// if the local pattern has a specified type, do not lint.
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else if let Some(_) = higher::VecArgs::hir(cx, expr)
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&& let Node::Local(local) = cx.tcx.hir().get_parent(expr.hir_id)
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&& local.ty.is_some()
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{
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let span = expr.span.ctxt().outer_expn_data().call_site;
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self.span_to_lint_map.insert(span, None);
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}
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// search for `for _ in vec![...]`
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else if let Some(parent) = get_parent_expr(cx, expr)
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&& parent.span.is_desugaring(DesugaringKind::ForLoop)
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&& self.msrv.meets(msrvs::ARRAY_INTO_ITERATOR)
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{
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// report the error around the `vec!` not inside `<std macros>:`
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let span = expr.span.ctxt().outer_expn_data().call_site;
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self.check_vec_macro(cx, &vec_args, span, expr.hir_id, SuggestedType::Array);
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}
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// search for `&vec![_]` or `vec![_]` expressions where the adjusted type is `&[_]`
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else {
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let (suggest_slice, span) = if let ExprKind::AddrOf(BorrowKind::Ref, mutability, _) = expr.kind {
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// `expr` is `&vec![_]`, so suggest `&[_]` (or `&mut[_]` resp.)
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(SuggestedType::SliceRef(mutability), expr.span)
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} else {
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// `expr` is the `vec![_]` expansion, so suggest `[_]`
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// and also use the span of the actual `vec![_]` expression
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(SuggestedType::Array, expr.span.ctxt().outer_expn_data().call_site)
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};
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if only_slice_uses {
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self.check_vec_macro(
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cx,
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&vec_args,
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expr.span.ctxt().outer_expn_data().call_site,
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SuggestedType::Array,
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);
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if adjusts_to_slice(cx, expr) {
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self.check_vec_macro(cx, &vec_args, span, expr.hir_id, suggest_slice);
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} else {
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self.span_to_lint_map.insert(span, None);
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}
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}
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}
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}
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// search for `for _ in vec![…]`
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if let Some(higher::ForLoop { arg, .. }) = higher::ForLoop::hir(expr)
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&& let Some(vec_args) = higher::VecArgs::hir(cx, arg)
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&& self.msrv.meets(msrvs::ARRAY_INTO_ITERATOR)
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{
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// report the error around the `vec!` not inside `<std macros>:`
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let span = arg.span.ctxt().outer_expn_data().call_site;
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self.check_vec_macro(cx, &vec_args, span, SuggestedType::Array);
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fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
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for (span, lint_opt) in &self.span_to_lint_map {
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if let Some((hir_id, suggest_slice, snippet, applicability)) = lint_opt {
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let help_msg = format!(
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"you can use {} directly",
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match suggest_slice {
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SuggestedType::SliceRef(_) => "a slice",
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SuggestedType::Array => "an array",
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}
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);
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span_lint_hir_and_then(cx, USELESS_VEC, *hir_id, *span, "useless use of `vec!`", |diag| {
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diag.span_suggestion(*span, help_msg, snippet, *applicability);
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});
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}
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}
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}
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@ -134,7 +160,7 @@ impl<'tcx> LateLintPass<'tcx> for UselessVec {
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}
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#[derive(Copy, Clone)]
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enum SuggestedType {
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pub(crate) enum SuggestedType {
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/// Suggest using a slice `&[..]` / `&mut [..]`
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SliceRef(Mutability),
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/// Suggest using an array: `[..]`
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@ -147,6 +173,7 @@ impl UselessVec {
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cx: &LateContext<'tcx>,
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vec_args: &higher::VecArgs<'tcx>,
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span: Span,
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hir_id: HirId,
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suggest_slice: SuggestedType,
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) {
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if span.from_expansion() {
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@ -204,21 +231,9 @@ impl UselessVec {
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},
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};
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span_lint_and_sugg(
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cx,
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USELESS_VEC,
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span,
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"useless use of `vec!`",
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&format!(
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"you can use {} directly",
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match suggest_slice {
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SuggestedType::SliceRef(_) => "a slice",
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SuggestedType::Array => "an array",
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}
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),
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snippet,
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applicability,
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);
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self.span_to_lint_map
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.entry(span)
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.or_insert(Some((hir_id, suggest_slice, snippet, applicability)));
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}
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}
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@ -176,3 +176,37 @@ fn below() {
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let _: String = a;
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}
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}
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fn func_needing_vec(_bar: usize, _baz: Vec<usize>) {}
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fn func_not_needing_vec(_bar: usize, _baz: usize) {}
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fn issue11861() {
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macro_rules! this_macro_needs_vec {
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($x:expr) => {{
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func_needing_vec($x.iter().sum(), $x);
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for _ in $x {}
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}};
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}
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macro_rules! this_macro_doesnt_need_vec {
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($x:expr) => {{ func_not_needing_vec($x.iter().sum(), $x.iter().sum()) }};
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}
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// Do not lint the next line
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this_macro_needs_vec!(vec![1]);
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this_macro_doesnt_need_vec!([1]); //~ ERROR: useless use of `vec!`
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macro_rules! m {
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($x:expr) => {
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fn f2() {
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let _x: Vec<i32> = $x;
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}
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fn f() {
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let _x = $x;
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$x.starts_with(&[]);
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}
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};
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}
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// should not lint
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m!(vec![1]);
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}
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@ -176,3 +176,37 @@ fn below() {
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let _: String = a;
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}
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}
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fn func_needing_vec(_bar: usize, _baz: Vec<usize>) {}
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fn func_not_needing_vec(_bar: usize, _baz: usize) {}
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fn issue11861() {
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macro_rules! this_macro_needs_vec {
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($x:expr) => {{
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func_needing_vec($x.iter().sum(), $x);
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for _ in $x {}
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}};
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}
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macro_rules! this_macro_doesnt_need_vec {
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($x:expr) => {{ func_not_needing_vec($x.iter().sum(), $x.iter().sum()) }};
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}
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// Do not lint the next line
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this_macro_needs_vec!(vec![1]);
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this_macro_doesnt_need_vec!(vec![1]); //~ ERROR: useless use of `vec!`
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macro_rules! m {
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($x:expr) => {
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fn f2() {
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let _x: Vec<i32> = $x;
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}
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fn f() {
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let _x = $x;
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$x.starts_with(&[]);
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}
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};
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}
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// should not lint
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m!(vec![1]);
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}
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@ -115,5 +115,11 @@ error: useless use of `vec!`
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LL | for a in vec![String::new(), String::new()] {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: you can use an array directly: `[String::new(), String::new()]`
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error: aborting due to 19 previous errors
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error: useless use of `vec!`
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--> $DIR/vec.rs:196:33
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LL | this_macro_doesnt_need_vec!(vec![1]);
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| ^^^^^^^ help: you can use an array directly: `[1]`
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error: aborting due to 20 previous errors
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