use crate::consts::{constant, Constant}; use crate::utils::{match_def_path, paths, span_lint, span_lint_and_help}; use if_chain::if_chain; use rustc_ast::ast::{LitKind, StrStyle}; use rustc_data_structures::fx::FxHashSet; use rustc_hir::{BorrowKind, Expr, ExprKind, HirId}; use rustc_lint::{LateContext, LateLintPass}; use rustc_session::{declare_tool_lint, impl_lint_pass}; use rustc_span::source_map::{BytePos, Span}; use std::convert::TryFrom; declare_clippy_lint! { /// **What it does:** Checks [regex](https://crates.io/crates/regex) creation /// (with `Regex::new`, `RegexBuilder::new`, or `RegexSet::new`) for correct /// regex syntax. /// /// **Why is this bad?** This will lead to a runtime panic. /// /// **Known problems:** None. /// /// **Example:** /// ```ignore /// Regex::new("|") /// ``` pub INVALID_REGEX, correctness, "invalid regular expressions" } declare_clippy_lint! { /// **What it does:** Checks for trivial [regex](https://crates.io/crates/regex) /// creation (with `Regex::new`, `RegexBuilder::new`, or `RegexSet::new`). /// /// **Why is this bad?** Matching the regex can likely be replaced by `==` or /// `str::starts_with`, `str::ends_with` or `std::contains` or other `str` /// methods. /// /// **Known problems:** None. /// /// **Example:** /// ```ignore /// Regex::new("^foobar") /// ``` pub TRIVIAL_REGEX, style, "trivial regular expressions" } #[derive(Clone, Default)] pub struct Regex { spans: FxHashSet, last: Option, } impl_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]); impl<'tcx> LateLintPass<'tcx> for Regex { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { if_chain! { if let ExprKind::Call(ref fun, ref args) = expr.kind; if let ExprKind::Path(ref qpath) = fun.kind; if args.len() == 1; if let Some(def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id(); then { if match_def_path(cx, def_id, &paths::REGEX_NEW) || match_def_path(cx, def_id, &paths::REGEX_BUILDER_NEW) { check_regex(cx, &args[0], true); } else if match_def_path(cx, def_id, &paths::REGEX_BYTES_NEW) || match_def_path(cx, def_id, &paths::REGEX_BYTES_BUILDER_NEW) { check_regex(cx, &args[0], false); } else if match_def_path(cx, def_id, &paths::REGEX_SET_NEW) { check_set(cx, &args[0], true); } else if match_def_path(cx, def_id, &paths::REGEX_BYTES_SET_NEW) { check_set(cx, &args[0], false); } } } } } #[allow(clippy::cast_possible_truncation)] // truncation very unlikely here #[must_use] fn str_span(base: Span, c: regex_syntax::ast::Span, offset: u16) -> Span { let offset = u32::from(offset); let end = base.lo() + BytePos(u32::try_from(c.end.offset).expect("offset too large") + offset); let start = base.lo() + BytePos(u32::try_from(c.start.offset).expect("offset too large") + offset); assert!(start <= end); Span::new(start, end, base.ctxt()) } fn const_str<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option { constant(cx, cx.typeck_results(), e).and_then(|(c, _)| match c { Constant::Str(s) => Some(s), _ => None, }) } fn is_trivial_regex(s: ®ex_syntax::hir::Hir) -> Option<&'static str> { use regex_syntax::hir::Anchor::{EndText, StartText}; use regex_syntax::hir::HirKind::{Alternation, Anchor, Concat, Empty, Literal}; let is_literal = |e: &[regex_syntax::hir::Hir]| e.iter().all(|e| matches!(*e.kind(), Literal(_))); match *s.kind() { Empty | Anchor(_) => Some("the regex is unlikely to be useful as it is"), Literal(_) => Some("consider using `str::contains`"), Alternation(ref exprs) => { if exprs.iter().all(|e| e.kind().is_empty()) { Some("the regex is unlikely to be useful as it is") } else { None } }, Concat(ref exprs) => match (exprs[0].kind(), exprs[exprs.len() - 1].kind()) { (&Anchor(StartText), &Anchor(EndText)) if exprs[1..(exprs.len() - 1)].is_empty() => { Some("consider using `str::is_empty`") }, (&Anchor(StartText), &Anchor(EndText)) if is_literal(&exprs[1..(exprs.len() - 1)]) => { Some("consider using `==` on `str`s") }, (&Anchor(StartText), &Literal(_)) if is_literal(&exprs[1..]) => Some("consider using `str::starts_with`"), (&Literal(_), &Anchor(EndText)) if is_literal(&exprs[1..(exprs.len() - 1)]) => { Some("consider using `str::ends_with`") }, _ if is_literal(exprs) => Some("consider using `str::contains`"), _ => None, }, _ => None, } } fn check_set<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) { if_chain! { if let ExprKind::AddrOf(BorrowKind::Ref, _, ref expr) = expr.kind; if let ExprKind::Array(exprs) = expr.kind; then { for expr in exprs { check_regex(cx, expr, utf8); } } } } fn check_regex<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, utf8: bool) { let mut parser = regex_syntax::ParserBuilder::new() .unicode(true) .allow_invalid_utf8(!utf8) .build(); if let ExprKind::Lit(ref lit) = expr.kind { if let LitKind::Str(ref r, style) = lit.node { let r = &r.as_str(); let offset = if let StrStyle::Raw(n) = style { 2 + n } else { 1 }; match parser.parse(r) { Ok(r) => { if let Some(repl) = is_trivial_regex(&r) { span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl); } }, Err(regex_syntax::Error::Parse(e)) => { span_lint( cx, INVALID_REGEX, str_span(expr.span, *e.span(), offset), &format!("regex syntax error: {}", e.kind()), ); }, Err(regex_syntax::Error::Translate(e)) => { span_lint( cx, INVALID_REGEX, str_span(expr.span, *e.span(), offset), &format!("regex syntax error: {}", e.kind()), ); }, Err(e) => { span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {}", e)); }, } } } else if let Some(r) = const_str(cx, expr) { match parser.parse(&r) { Ok(r) => { if let Some(repl) = is_trivial_regex(&r) { span_lint_and_help(cx, TRIVIAL_REGEX, expr.span, "trivial regex", None, repl); } }, Err(regex_syntax::Error::Parse(e)) => { span_lint( cx, INVALID_REGEX, expr.span, &format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()), ); }, Err(regex_syntax::Error::Translate(e)) => { span_lint( cx, INVALID_REGEX, expr.span, &format!("regex syntax error on position {}: {}", e.span().start.offset, e.kind()), ); }, Err(e) => { span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error: {}", e)); }, } } }