// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use regex_syntax; use crate::rustc::hir::*; use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; use crate::rustc::{declare_tool_lint, lint_array}; use crate::rustc_data_structures::fx::FxHashSet; use if_chain::if_chain; use crate::syntax::ast::{LitKind, NodeId, StrStyle}; use crate::syntax::source_map::{BytePos, Span}; use crate::utils::{is_expn_of, match_def_path, match_type, opt_def_id, paths, span_help_and_lint, span_lint}; use crate::consts::{constant, Constant}; use std::convert::TryInto; /// **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:** /// ```rust /// Regex::new("|") /// ``` declare_clippy_lint! { pub INVALID_REGEX, correctness, "invalid regular expressions" } /// **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:** /// ```rust /// Regex::new("^foobar") /// ``` declare_clippy_lint! { pub TRIVIAL_REGEX, style, "trivial regular expressions" } /// **What it does:** Checks for usage of `regex!(_)` which (as of now) is /// usually slower than `Regex::new(_)` unless called in a loop (which is a bad /// idea anyway). /// /// **Why is this bad?** Performance, at least for now. The macro version is /// likely to catch up long-term, but for now the dynamic version is faster. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// regex!("foo|bar") /// ``` declare_clippy_lint! { pub REGEX_MACRO, style, "use of `regex!(_)` instead of `Regex::new(_)`" } #[derive(Clone, Default)] pub struct Pass { spans: FxHashSet, last: Option, } impl LintPass for Pass { fn get_lints(&self) -> LintArray { lint_array!(INVALID_REGEX, REGEX_MACRO, TRIVIAL_REGEX) } } impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass { fn check_crate(&mut self, _: &LateContext<'a, 'tcx>, _: &'tcx Crate) { self.spans.clear(); } fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx Block) { if_chain! { if self.last.is_none(); if let Some(ref expr) = block.expr; if match_type(cx, cx.tables.expr_ty(expr), &paths::REGEX); if let Some(span) = is_expn_of(expr.span, "regex"); then { if !self.spans.contains(&span) { span_lint(cx, REGEX_MACRO, span, "`regex!(_)` found. \ Please use `Regex::new(_)`, which is faster for now."); self.spans.insert(span); } self.last = Some(block.id); } } } fn check_block_post(&mut self, _: &LateContext<'a, 'tcx>, block: &'tcx Block) { if self.last.map_or(false, |id| block.id == id) { self.last = None; } } fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) { if_chain! { if let ExprKind::Call(ref fun, ref args) = expr.node; if let ExprKind::Path(ref qpath) = fun.node; if args.len() == 1; if let Some(def_id) = opt_def_id(cx.tables.qpath_def(qpath, fun.hir_id)); then { if match_def_path(cx.tcx, def_id, &paths::REGEX_NEW) || match_def_path(cx.tcx, def_id, &paths::REGEX_BUILDER_NEW) { check_regex(cx, &args[0], true); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_NEW) || match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_BUILDER_NEW) { check_regex(cx, &args[0], false); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_SET_NEW) { check_set(cx, &args[0], true); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_SET_NEW) { check_set(cx, &args[0], false); } } } } } fn str_span(base: Span, c: regex_syntax::ast::Span, offset: u16) -> Span { let offset = u32::from(offset); let end = base.lo() + BytePos( c.end .offset .try_into() .ok() .and_then(|o: u32| o.checked_add(offset)) .expect("offset too large"), ); let start = base.lo() + BytePos( c.start .offset .try_into() .ok() .and_then(|o: u32| o.checked_add(offset)) .expect("offset too large"), ); assert!(start <= end); Span::new(start, end, base.ctxt()) } fn const_str<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) -> Option { constant(cx, cx.tables, 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::HirKind::*; use regex_syntax::hir::Anchor::*; let is_literal = |e: &[regex_syntax::hir::Hir]| e.iter().all(|e| match *e.kind() { Literal(_) => true, _ => false, }); 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<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, utf8: bool) { if_chain! { if let ExprKind::AddrOf(_, ref expr) = expr.node; if let ExprKind::Array(ref exprs) = expr.node; then { for expr in exprs { check_regex(cx, expr, utf8); } } } } fn check_regex<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr, utf8: bool) { let mut parser = regex_syntax::ParserBuilder::new() .unicode(utf8) .allow_invalid_utf8(!utf8) .build(); if let ExprKind::Lit(ref lit) = expr.node { 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_help_and_lint( cx, TRIVIAL_REGEX, expr.span, "trivial regex", 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_help_and_lint( cx, TRIVIAL_REGEX, expr.span, "trivial regex", 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), ); }, } } }