-use crate::utils::{match_def_path, path_to_local, path_to_local_id, paths, span_lint_and_sugg};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::higher::{get_vec_init_kind, VecInitKind};
use clippy_utils::source::snippet;
-use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::{path_to_local, path_to_local_id};
use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, Local, PatKind, QPath, Stmt, StmtKind};
+use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, Local, PatKind, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::{symbol::sym, Span};
-use std::convert::TryInto;
+use rustc_span::Span;
declare_clippy_lint! {
- /// **What it does:** Checks for calls to `push` immediately after creating a new `Vec`.
+ /// ### What it does
+ /// Checks for calls to `push` immediately after creating a new `Vec`.
///
- /// **Why is this bad?** The `vec![]` macro is both more performant and easier to read than
+ /// ### Why is this bad?
+ /// The `vec![]` macro is both more performant and easier to read than
/// multiple `push` calls.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
/// let mut v = Vec::new();
/// v.push(0);
/// ```rust
/// let v = vec![0];
/// ```
+ #[clippy::version = "1.51.0"]
pub VEC_INIT_THEN_PUSH,
perf,
"`push` immediately after `Vec` creation"
searcher: Option<VecPushSearcher>,
}
-#[derive(Clone, Copy)]
-enum VecInitKind {
- New,
- WithCapacity(u64),
-}
struct VecPushSearcher {
local_id: HirId,
init: VecInitKind,
fn display_err(&self, cx: &LateContext<'_>) {
match self.init {
_ if self.found == 0 => return,
- VecInitKind::WithCapacity(x) if x > self.found => return,
+ VecInitKind::WithLiteralCapacity(x) if x > self.found => return,
+ VecInitKind::WithExprCapacity(_) => return,
_ => (),
};
}
}
-impl LateLintPass<'_> for VecInitThenPush {
+impl<'tcx> LateLintPass<'tcx> for VecInitThenPush {
fn check_block(&mut self, _: &LateContext<'tcx>, _: &'tcx Block<'tcx>) {
self.searcher = None;
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
- if self.searcher.is_none() {
- if_chain! {
- if !in_external_macro(cx.sess(), expr.span);
- if let ExprKind::Assign(left, right, _) = expr.kind;
- if let Some(id) = path_to_local(left);
- if let Some(init_kind) = get_vec_init_kind(cx, right);
- then {
- self.searcher = Some(VecPushSearcher {
- local_id: id,
- init: init_kind,
- lhs_is_local: false,
- lhs_span: left.span,
- err_span: expr.span,
- found: 0,
- });
- }
+ if_chain! {
+ if self.searcher.is_none();
+ if !in_external_macro(cx.sess(), expr.span);
+ if let ExprKind::Assign(left, right, _) = expr.kind;
+ if let Some(id) = path_to_local(left);
+ if let Some(init_kind) = get_vec_init_kind(cx, right);
+ then {
+ self.searcher = Some(VecPushSearcher {
+ local_id: id,
+ init: init_kind,
+ lhs_is_local: false,
+ lhs_span: left.span,
+ err_span: expr.span,
+ found: 0,
+ });
}
}
}
if let Some(searcher) = self.searcher.take() {
if_chain! {
if let StmtKind::Expr(expr) | StmtKind::Semi(expr) = stmt.kind;
- if let ExprKind::MethodCall(path, _, [self_arg, _], _) = expr.kind;
+ if let ExprKind::MethodCall(path, [self_arg, _], _) = expr.kind;
if path_to_local_id(self_arg, searcher.local_id);
if path.ident.name.as_str() == "push";
then {
}
}
}
-
-fn get_vec_init_kind<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<VecInitKind> {
- if let ExprKind::Call(func, args) = expr.kind {
- match func.kind {
- ExprKind::Path(QPath::TypeRelative(ty, name))
- if is_type_diagnostic_item(cx, cx.typeck_results().node_type(ty.hir_id), sym::vec_type) =>
- {
- if name.ident.name == sym::new {
- return Some(VecInitKind::New);
- } else if name.ident.name.as_str() == "with_capacity" {
- return args.get(0).and_then(|arg| {
- if_chain! {
- if let ExprKind::Lit(lit) = &arg.kind;
- if let LitKind::Int(num, _) = lit.node;
- then {
- Some(VecInitKind::WithCapacity(num.try_into().ok()?))
- } else {
- None
- }
- }
- });
- }
- }
- ExprKind::Path(QPath::Resolved(_, path))
- if match_def_path(cx, path.res.opt_def_id()?, &paths::DEFAULT_TRAIT_METHOD)
- && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::vec_type) =>
- {
- return Some(VecInitKind::New);
- }
- _ => (),
- }
- }
- None
-}