mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
211 lines
8 KiB
Rust
211 lines
8 KiB
Rust
use crate::consts::{constant, Constant};
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use crate::utils::{match_def_path, paths, span_lint, span_lint_and_help};
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use if_chain::if_chain;
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use rustc_ast::ast::{LitKind, StrStyle};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_hir::{BorrowKind, Expr, ExprKind, HirId};
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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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use std::convert::TryFrom;
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declare_clippy_lint! {
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/// **What it does:** 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?** This will lead to a runtime panic.
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///
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/// **Known problems:** None.
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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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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:** 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?** 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:** 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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pub TRIVIAL_REGEX,
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nursery,
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"trivial regular expressions"
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}
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#[derive(Clone, Default)]
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pub struct Regex {
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spans: FxHashSet<Span>,
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last: Option<HirId>,
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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_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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if_chain! {
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if let ExprKind::Call(ref fun, ref args) = expr.kind;
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if let ExprKind::Path(ref qpath) = fun.kind;
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if args.len() == 1;
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if let Some(def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id();
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then {
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if match_def_path(cx, def_id, &paths::REGEX_NEW) ||
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match_def_path(cx, def_id, &paths::REGEX_BUILDER_NEW) {
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check_regex(cx, &args[0], true);
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} else if match_def_path(cx, def_id, &paths::REGEX_BYTES_NEW) ||
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match_def_path(cx, def_id, &paths::REGEX_BYTES_BUILDER_NEW) {
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check_regex(cx, &args[0], false);
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} else if match_def_path(cx, def_id, &paths::REGEX_SET_NEW) {
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check_set(cx, &args[0], true);
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} else if match_def_path(cx, def_id, &paths::REGEX_BYTES_SET_NEW) {
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check_set(cx, &args[0], false);
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}
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}
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}
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}
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}
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#[allow(clippy::cast_possible_truncation)] // truncation very unlikely here
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#[must_use]
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fn str_span(base: Span, c: regex_syntax::ast::Span, offset: u16) -> Span {
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let offset = u32::from(offset);
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let end = base.lo() + BytePos(u32::try_from(c.end.offset).expect("offset too large") + offset);
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let start = base.lo() + BytePos(u32::try_from(c.start.offset).expect("offset too large") + offset);
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assert!(start <= end);
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Span::new(start, end, base.ctxt())
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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::Anchor::{EndText, StartText};
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use regex_syntax::hir::HirKind::{Alternation, Anchor, Concat, Empty, Literal};
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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 | Anchor(_) => 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| e.kind().is_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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(&Anchor(StartText), &Anchor(EndText)) 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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(&Anchor(StartText), &Anchor(EndText)) 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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(&Anchor(StartText), &Literal(_)) if is_literal(&exprs[1..]) => Some("consider using `str::starts_with`"),
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(&Literal(_), &Anchor(EndText)) 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, _, 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()
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.unicode(true)
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.allow_invalid_utf8(!utf8)
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.build();
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if let ExprKind::Lit(ref 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(regex_syntax::Error::Parse(e)) => {
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span_lint(
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cx,
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INVALID_REGEX,
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str_span(expr.span, *e.span(), offset),
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&format!("regex syntax error: {}", e.kind()),
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);
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},
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Err(regex_syntax::Error::Translate(e)) => {
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span_lint(
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cx,
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INVALID_REGEX,
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str_span(expr.span, *e.span(), offset),
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&format!("regex syntax error: {}", e.kind()),
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);
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},
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Err(e) => {
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span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {}", e));
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},
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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(regex_syntax::Error::Parse(e)) => {
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span_lint(
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cx,
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INVALID_REGEX,
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expr.span,
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&format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()),
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);
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},
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Err(regex_syntax::Error::Translate(e)) => {
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span_lint(
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cx,
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INVALID_REGEX,
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expr.span,
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&format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()),
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);
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},
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Err(e) => {
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span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {}", e));
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},
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}
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}
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}
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