-use crate::utils::{
- contains_name, get_pat_name, match_type, paths, single_segment_path, snippet_with_applicability, span_lint_and_sugg,
-};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_with_applicability;
+use clippy_utils::ty::match_type;
+use clippy_utils::visitors::is_local_used;
+use clippy_utils::{path_to_local_id, paths, peel_ref_operators, remove_blocks, strip_pat_refs};
use if_chain::if_chain;
-use rustc_ast::ast::UintTy;
use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp};
+use rustc_hir::{BinOpKind, Expr, ExprKind, PatKind};
use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty;
+use rustc_middle::ty::{self, UintTy};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
-use rustc_span::Symbol;
declare_clippy_lint! {
- /// **What it does:** Checks for naive byte counts
+ /// ### What it does
+ /// Checks for naive byte counts
///
- /// **Why is this bad?** The [`bytecount`](https://crates.io/crates/bytecount)
+ /// ### Why is this bad?
+ /// The [`bytecount`](https://crates.io/crates/bytecount)
/// crate has methods to count your bytes faster, especially for large slices.
///
- /// **Known problems:** If you have predominantly small slices, the
+ /// ### Known problems
+ /// If you have predominantly small slices, the
/// `bytecount::count(..)` method may actually be slower. However, if you can
/// ensure that less than 2³²-1 matches arise, the `naive_count_32(..)` can be
/// faster in those cases.
///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
/// # let vec = vec![1_u8];
/// &vec.iter().filter(|x| **x == 0u8).count(); // use bytecount::count instead
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub NAIVE_BYTECOUNT,
- perf,
+ pedantic,
"use of naive `<slice>.filter(|&x| x == y).count()` to count byte values"
}
impl<'tcx> LateLintPass<'tcx> for ByteCount {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
- if let ExprKind::MethodCall(ref count, _, ref count_args, _) = expr.kind;
+ if let ExprKind::MethodCall(count, _, [count_recv], _) = expr.kind;
if count.ident.name == sym!(count);
- if count_args.len() == 1;
- if let ExprKind::MethodCall(ref filter, _, ref filter_args, _) = count_args[0].kind;
+ if let ExprKind::MethodCall(filter, _, [filter_recv, filter_arg], _) = count_recv.kind;
if filter.ident.name == sym!(filter);
- if filter_args.len() == 2;
- if let ExprKind::Closure(_, _, body_id, _, _) = filter_args[1].kind;
+ if let ExprKind::Closure(_, _, body_id, _, _) = filter_arg.kind;
+ let body = cx.tcx.hir().body(body_id);
+ if let [param] = body.params;
+ if let PatKind::Binding(_, arg_id, _, _) = strip_pat_refs(param.pat).kind;
+ if let ExprKind::Binary(ref op, l, r) = body.value.kind;
+ if op.node == BinOpKind::Eq;
+ if match_type(cx,
+ cx.typeck_results().expr_ty(filter_recv).peel_refs(),
+ &paths::SLICE_ITER);
+ let operand_is_arg = |expr| {
+ let expr = peel_ref_operators(cx, remove_blocks(expr));
+ path_to_local_id(expr, arg_id)
+ };
+ let needle = if operand_is_arg(l) {
+ r
+ } else if operand_is_arg(r) {
+ l
+ } else {
+ return;
+ };
+ if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(needle).peel_refs().kind();
+ if !is_local_used(cx, needle, arg_id);
then {
- let body = cx.tcx.hir().body(body_id);
- if_chain! {
- if body.params.len() == 1;
- if let Some(argname) = get_pat_name(&body.params[0].pat);
- if let ExprKind::Binary(ref op, ref l, ref r) = body.value.kind;
- if op.node == BinOpKind::Eq;
- if match_type(cx,
- cx.typeck_results().expr_ty(&filter_args[0]).peel_refs(),
- &paths::SLICE_ITER);
- then {
- let needle = match get_path_name(l) {
- Some(name) if check_arg(name, argname, r) => r,
- _ => match get_path_name(r) {
- Some(name) if check_arg(name, argname, l) => l,
- _ => { return; }
- }
- };
- if ty::Uint(UintTy::U8) != *cx.typeck_results().expr_ty(needle).peel_refs().kind() {
- return;
- }
- let haystack = if let ExprKind::MethodCall(ref path, _, ref args, _) =
- filter_args[0].kind {
- let p = path.ident.name;
- if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
- &args[0]
- } else {
- &filter_args[0]
- }
- } else {
- &filter_args[0]
- };
- let mut applicability = Applicability::MaybeIncorrect;
- span_lint_and_sugg(
- cx,
- NAIVE_BYTECOUNT,
- expr.span,
- "you appear to be counting bytes the naive way",
- "consider using the bytecount crate",
- format!("bytecount::count({}, {})",
- snippet_with_applicability(cx, haystack.span, "..", &mut applicability),
- snippet_with_applicability(cx, needle.span, "..", &mut applicability)),
- applicability,
- );
+ let haystack = if let ExprKind::MethodCall(path, _, args, _) =
+ filter_recv.kind {
+ let p = path.ident.name;
+ if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
+ &args[0]
+ } else {
+ filter_recv
}
+ } else {
+ filter_recv
};
+ let mut applicability = Applicability::MaybeIncorrect;
+ span_lint_and_sugg(
+ cx,
+ NAIVE_BYTECOUNT,
+ expr.span,
+ "you appear to be counting bytes the naive way",
+ "consider using the bytecount crate",
+ format!("bytecount::count({}, {})",
+ snippet_with_applicability(cx, haystack.span, "..", &mut applicability),
+ snippet_with_applicability(cx, needle.span, "..", &mut applicability)),
+ applicability,
+ );
}
};
}
}
-
-fn check_arg(name: Symbol, arg: Symbol, needle: &Expr<'_>) -> bool {
- name == arg && !contains_name(name, needle)
-}
-
-fn get_path_name(expr: &Expr<'_>) -> Option<Symbol> {
- match expr.kind {
- ExprKind::Box(ref e) | ExprKind::AddrOf(BorrowKind::Ref, _, ref e) | ExprKind::Unary(UnOp::UnDeref, ref e) => {
- get_path_name(e)
- },
- ExprKind::Block(ref b, _) => {
- if b.stmts.is_empty() {
- b.expr.as_ref().and_then(|p| get_path_name(p))
- } else {
- None
- }
- },
- ExprKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
- _ => None,
- }
-}
projects / rust.git / blobdiff