2018-11-20 13:06:29 +00:00
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use crate::utils::{
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2020-09-24 12:49:22 +00:00
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contains_name, get_pat_name, match_type, paths, single_segment_path, snippet_with_applicability, span_lint_and_sugg,
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2018-11-20 13:06:29 +00:00
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};
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use if_chain::if_chain;
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2020-05-17 15:36:26 +00:00
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use rustc_ast::ast::UintTy;
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2018-12-29 15:04:45 +00:00
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use rustc_errors::Applicability;
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2020-02-21 08:39:38 +00:00
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use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp};
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2020-01-12 06:08:41 +00:00
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use rustc_lint::{LateContext, LateLintPass};
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2020-03-30 09:02:14 +00:00
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use rustc_middle::ty;
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2020-01-11 11:37:08 +00:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2020-11-05 13:29:48 +00:00
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use rustc_span::sym;
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2020-05-08 11:57:01 +00:00
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use rustc_span::Symbol;
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2017-08-22 21:45:08 +00:00
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2019-03-05 16:50:33 +00:00
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/// **What it does:** Checks for naive byte counts
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///
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/// **Why is this bad?** The [`bytecount`](https://crates.io/crates/bytecount)
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/// crate has methods to count your bytes faster, especially for large slices.
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///
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/// **Known problems:** If you have predominantly small slices, the
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/// `bytecount::count(..)` method may actually be slower. However, if you can
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/// ensure that less than 2³²-1 matches arise, the `naive_count_32(..)` can be
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/// faster in those cases.
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///
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/// **Example:**
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///
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/// ```rust
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2019-08-03 06:01:27 +00:00
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/// # let vec = vec![1_u8];
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/// &vec.iter().filter(|x| **x == 0u8).count(); // use bytecount::count instead
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2019-03-05 16:50:33 +00:00
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/// ```
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2017-08-22 21:45:08 +00:00
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pub NAIVE_BYTECOUNT,
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2018-03-28 13:24:26 +00:00
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perf,
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2017-08-22 21:45:08 +00:00
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"use of naive `<slice>.filter(|&x| x == y).count()` to count byte values"
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}
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(ByteCount => [NAIVE_BYTECOUNT]);
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2017-08-22 21:45:08 +00:00
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2020-06-25 20:41:36 +00:00
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impl<'tcx> LateLintPass<'tcx> for ByteCount {
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fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
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2017-10-23 19:18:02 +00:00
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if_chain! {
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2020-06-09 21:44:04 +00:00
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if let ExprKind::MethodCall(ref count, _, ref count_args, _) = expr.kind;
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2019-05-17 21:53:54 +00:00
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if count.ident.name == sym!(count);
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2017-10-23 19:18:02 +00:00
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if count_args.len() == 1;
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2020-06-09 21:44:04 +00:00
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if let ExprKind::MethodCall(ref filter, _, ref filter_args, _) = count_args[0].kind;
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2019-05-17 21:53:54 +00:00
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if filter.ident.name == sym!(filter);
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2017-10-23 19:18:02 +00:00
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if filter_args.len() == 2;
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2019-09-27 15:16:06 +00:00
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if let ExprKind::Closure(_, _, body_id, _, _) = filter_args[1].kind;
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2017-10-23 19:18:02 +00:00
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then {
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2018-12-08 00:56:03 +00:00
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let body = cx.tcx.hir().body(body_id);
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2017-10-23 19:18:02 +00:00
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if_chain! {
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2019-08-28 09:27:06 +00:00
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if body.params.len() == 1;
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if let Some(argname) = get_pat_name(&body.params[0].pat);
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2019-09-27 15:16:06 +00:00
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if let ExprKind::Binary(ref op, ref l, ref r) = body.value.kind;
|
2018-07-12 07:50:09 +00:00
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if op.node == BinOpKind::Eq;
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2017-10-23 19:18:02 +00:00
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if match_type(cx,
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2020-09-24 12:49:22 +00:00
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cx.typeck_results().expr_ty(&filter_args[0]).peel_refs(),
|
2019-05-17 21:53:54 +00:00
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&paths::SLICE_ITER);
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2017-10-23 19:18:02 +00:00
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then {
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let needle = match get_path_name(l) {
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Some(name) if check_arg(name, argname, r) => r,
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_ => match get_path_name(r) {
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Some(name) if check_arg(name, argname, l) => l,
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_ => { return; }
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}
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|
};
|
2020-09-24 12:49:22 +00:00
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if ty::Uint(UintTy::U8) != *cx.typeck_results().expr_ty(needle).peel_refs().kind() {
|
2017-10-23 19:18:02 +00:00
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|
return;
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|
}
|
2020-06-09 21:44:04 +00:00
|
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|
let haystack = if let ExprKind::MethodCall(ref path, _, ref args, _) =
|
2019-09-27 15:16:06 +00:00
|
|
|
filter_args[0].kind {
|
2018-06-28 13:46:58 +00:00
|
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|
let p = path.ident.name;
|
2020-11-05 13:29:48 +00:00
|
|
|
if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
|
2017-10-23 19:18:02 +00:00
|
|
|
&args[0]
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|
} else {
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|
|
|
&filter_args[0]
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|
}
|
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|
} else {
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|
|
|
&filter_args[0]
|
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|
};
|
2019-04-17 18:46:42 +00:00
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|
let mut applicability = Applicability::MaybeIncorrect;
|
2018-11-20 13:06:29 +00:00
|
|
|
span_lint_and_sugg(
|
|
|
|
cx,
|
|
|
|
NAIVE_BYTECOUNT,
|
|
|
|
expr.span,
|
2020-08-11 13:43:21 +00:00
|
|
|
"you appear to be counting bytes the naive way",
|
|
|
|
"consider using the bytecount crate",
|
2018-11-20 13:06:29 +00:00
|
|
|
format!("bytecount::count({}, {})",
|
2018-11-27 14:13:57 +00:00
|
|
|
snippet_with_applicability(cx, haystack.span, "..", &mut applicability),
|
|
|
|
snippet_with_applicability(cx, needle.span, "..", &mut applicability)),
|
2018-11-27 16:31:17 +00:00
|
|
|
applicability,
|
2018-11-20 13:06:29 +00:00
|
|
|
);
|
2017-08-23 15:54:35 +00:00
|
|
|
}
|
|
|
|
};
|
2017-10-23 19:18:02 +00:00
|
|
|
}
|
|
|
|
};
|
2017-08-22 21:45:08 +00:00
|
|
|
}
|
|
|
|
}
|
2017-08-23 15:54:35 +00:00
|
|
|
|
2020-05-08 11:57:01 +00:00
|
|
|
fn check_arg(name: Symbol, arg: Symbol, needle: &Expr<'_>) -> bool {
|
2017-08-23 15:54:35 +00:00
|
|
|
name == arg && !contains_name(name, needle)
|
|
|
|
}
|
|
|
|
|
2020-05-08 11:57:01 +00:00
|
|
|
fn get_path_name(expr: &Expr<'_>) -> Option<Symbol> {
|
2019-09-27 15:16:06 +00:00
|
|
|
match expr.kind {
|
2019-11-27 22:30:10 +00:00
|
|
|
ExprKind::Box(ref e) | ExprKind::AddrOf(BorrowKind::Ref, _, ref e) | ExprKind::Unary(UnOp::UnDeref, ref e) => {
|
2019-11-25 14:20:10 +00:00
|
|
|
get_path_name(e)
|
|
|
|
},
|
2018-11-27 20:14:15 +00:00
|
|
|
ExprKind::Block(ref b, _) => {
|
|
|
|
if b.stmts.is_empty() {
|
|
|
|
b.expr.as_ref().and_then(|p| get_path_name(p))
|
|
|
|
} else {
|
|
|
|
None
|
|
|
|
}
|
2017-09-03 21:15:15 +00:00
|
|
|
},
|
2018-07-12 07:30:57 +00:00
|
|
|
ExprKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
|
2017-09-03 21:15:15 +00:00
|
|
|
_ => None,
|
2017-08-23 15:54:35 +00:00
|
|
|
}
|
|
|
|
}
|