mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-01 00:49:30 +00:00
231 lines
8.4 KiB
Rust
231 lines
8.4 KiB
Rust
use std::fmt::Display;
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use clippy_utils::consts::{constant, Constant};
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use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
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use clippy_utils::source::snippet_opt;
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use clippy_utils::{def_path_def_ids, path_def_id, paths};
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use rustc_ast::ast::{LitKind, StrStyle};
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use rustc_hir::def_id::DefIdMap;
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use rustc_hir::{BorrowKind, Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::source_map::{BytePos, Span};
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declare_clippy_lint! {
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/// ### What it does
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/// Checks [regex](https://crates.io/crates/regex) creation
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/// (with `Regex::new`, `RegexBuilder::new`, or `RegexSet::new`) for correct
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/// regex syntax.
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///
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/// ### Why is this bad?
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/// This will lead to a runtime panic.
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///
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/// ### Example
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/// ```ignore
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/// Regex::new("(")
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub INVALID_REGEX,
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correctness,
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"invalid regular expressions"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for trivial [regex](https://crates.io/crates/regex)
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/// creation (with `Regex::new`, `RegexBuilder::new`, or `RegexSet::new`).
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///
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/// ### Why is this bad?
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/// Matching the regex can likely be replaced by `==` or
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/// `str::starts_with`, `str::ends_with` or `std::contains` or other `str`
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/// methods.
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///
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/// ### Known problems
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/// If the same regex is going to be applied to multiple
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/// inputs, the precomputations done by `Regex` construction can give
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/// significantly better performance than any of the `str`-based methods.
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///
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/// ### Example
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/// ```ignore
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/// Regex::new("^foobar")
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub TRIVIAL_REGEX,
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nursery,
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"trivial regular expressions"
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}
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#[derive(Copy, Clone)]
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enum RegexKind {
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Unicode,
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UnicodeSet,
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Bytes,
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BytesSet,
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}
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#[derive(Default)]
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pub struct Regex {
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definitions: DefIdMap<RegexKind>,
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}
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impl_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]);
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impl<'tcx> LateLintPass<'tcx> for Regex {
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fn check_crate(&mut self, cx: &LateContext<'tcx>) {
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// We don't use `match_def_path` here because that relies on matching the exact path, which changed
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// between regex 1.8 and 1.9
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//
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// `def_path_def_ids` will resolve through re-exports but is relatively heavy, so we only perform
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// the operation once and store the results
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let mut resolve = |path, kind| {
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for id in def_path_def_ids(cx, path) {
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self.definitions.insert(id, kind);
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}
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};
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resolve(&paths::REGEX_NEW, RegexKind::Unicode);
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resolve(&paths::REGEX_BUILDER_NEW, RegexKind::Unicode);
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resolve(&paths::REGEX_SET_NEW, RegexKind::UnicodeSet);
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resolve(&paths::REGEX_BYTES_NEW, RegexKind::Bytes);
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resolve(&paths::REGEX_BYTES_BUILDER_NEW, RegexKind::Bytes);
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resolve(&paths::REGEX_BYTES_SET_NEW, RegexKind::BytesSet);
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}
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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if let ExprKind::Call(fun, [arg]) = expr.kind
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&& let Some(def_id) = path_def_id(cx, fun)
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&& let Some(regex_kind) = self.definitions.get(&def_id)
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{
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match regex_kind {
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RegexKind::Unicode => check_regex(cx, arg, true),
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RegexKind::UnicodeSet => check_set(cx, arg, true),
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RegexKind::Bytes => check_regex(cx, arg, false),
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RegexKind::BytesSet => check_set(cx, arg, false),
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}
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}
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}
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}
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fn lint_syntax_error(cx: &LateContext<'_>, error: ®ex_syntax::Error, unescaped: &str, base: Span, offset: u8) {
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let parts: Option<(_, _, &dyn Display)> = match &error {
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regex_syntax::Error::Parse(e) => Some((e.span(), e.auxiliary_span(), e.kind())),
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regex_syntax::Error::Translate(e) => Some((e.span(), None, e.kind())),
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_ => None,
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};
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let convert_span = |regex_span: ®ex_syntax::ast::Span| {
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let offset = u32::from(offset);
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let start = base.lo() + BytePos(u32::try_from(regex_span.start.offset).expect("offset too large") + offset);
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let end = base.lo() + BytePos(u32::try_from(regex_span.end.offset).expect("offset too large") + offset);
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Span::new(start, end, base.ctxt(), base.parent())
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};
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if let Some((primary, auxiliary, kind)) = parts
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&& let Some(literal_snippet) = snippet_opt(cx, base)
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&& let Some(inner) = literal_snippet.get(offset as usize..)
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// Only convert to native rustc spans if the parsed regex matches the
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// source snippet exactly, to ensure the span offsets are correct
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&& inner.get(..unescaped.len()) == Some(unescaped)
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{
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let spans = if let Some(auxiliary) = auxiliary {
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vec![convert_span(primary), convert_span(auxiliary)]
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} else {
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vec![convert_span(primary)]
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};
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span_lint(cx, INVALID_REGEX, spans, &format!("regex syntax error: {kind}"));
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} else {
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span_lint_and_help(
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cx,
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INVALID_REGEX,
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base,
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&error.to_string(),
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None,
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"consider using a raw string literal: `r\"..\"`",
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);
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}
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}
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fn const_str<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<String> {
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constant(cx, cx.typeck_results(), e).and_then(|c| match c {
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Constant::Str(s) => Some(s),
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_ => None,
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})
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}
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fn is_trivial_regex(s: ®ex_syntax::hir::Hir) -> Option<&'static str> {
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use regex_syntax::hir::HirKind::{Alternation, Concat, Empty, Literal, Look};
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use regex_syntax::hir::Look as HirLook;
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let is_literal = |e: &[regex_syntax::hir::Hir]| e.iter().all(|e| matches!(*e.kind(), Literal(_)));
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match *s.kind() {
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Empty | Look(_) => Some("the regex is unlikely to be useful as it is"),
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Literal(_) => Some("consider using `str::contains`"),
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Alternation(ref exprs) => {
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if exprs.iter().all(|e| matches!(e.kind(), Empty)) {
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Some("the regex is unlikely to be useful as it is")
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} else {
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None
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}
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},
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Concat(ref exprs) => match (exprs[0].kind(), exprs[exprs.len() - 1].kind()) {
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(&Look(HirLook::Start), &Look(HirLook::End)) if exprs[1..(exprs.len() - 1)].is_empty() => {
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Some("consider using `str::is_empty`")
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},
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(&Look(HirLook::Start), &Look(HirLook::End)) if is_literal(&exprs[1..(exprs.len() - 1)]) => {
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Some("consider using `==` on `str`s")
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},
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(&Look(HirLook::Start), &Literal(_)) if is_literal(&exprs[1..]) => {
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Some("consider using `str::starts_with`")
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},
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(&Literal(_), &Look(HirLook::End)) if is_literal(&exprs[1..(exprs.len() - 1)]) => {
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Some("consider using `str::ends_with`")
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},
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_ if is_literal(exprs) => Some("consider using `str::contains`"),
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_ => None,
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},
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_ => None,
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}
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}
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fn check_set<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) {
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if_chain! {
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if let ExprKind::AddrOf(BorrowKind::Ref, _, expr) = expr.kind;
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if let ExprKind::Array(exprs) = expr.kind;
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then {
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for expr in exprs {
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check_regex(cx, expr, utf8);
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}
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}
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}
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}
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fn check_regex<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) {
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let mut parser = regex_syntax::ParserBuilder::new().unicode(true).utf8(utf8).build();
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if let ExprKind::Lit(lit) = expr.kind {
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if let LitKind::Str(ref r, style) = lit.node {
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let r = r.as_str();
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let offset = if let StrStyle::Raw(n) = style { 2 + n } else { 1 };
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match parser.parse(r) {
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Ok(r) => {
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if let Some(repl) = is_trivial_regex(&r) {
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span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl);
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}
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},
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Err(e) => lint_syntax_error(cx, &e, r, expr.span, offset),
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}
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}
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} else if let Some(r) = const_str(cx, expr) {
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match parser.parse(&r) {
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Ok(r) => {
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if let Some(repl) = is_trivial_regex(&r) {
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span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl);
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}
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},
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Err(e) => span_lint(cx, INVALID_REGEX, expr.span, &e.to_string()),
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}
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}
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}
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