use regex_syntax; use rustc::hir::*; use rustc::lint::*; use rustc::middle::const_val::ConstVal; use rustc_const_eval::EvalHint::ExprTypeChecked; use rustc_const_eval::eval_const_expr_partial; use std::collections::HashSet; use std::error::Error; use syntax::ast::{LitKind, NodeId}; use syntax::codemap::{Span, BytePos}; use syntax::parse::token::InternedString; use utils::{is_expn_of, match_def_path, match_type, paths, span_lint, span_help_and_lint}; /// **What it does:** This lint checks [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:** `Regex::new("|")` declare_lint! { pub INVALID_REGEX, Deny, "finds invalid regular expressions" } /// **What it does:** This lint checks for trivial [regex] creation (with `Regex::new`, /// `RegexBuilder::new` or `RegexSet::new`). /// /// **Why is this bad?** This can likely be replaced by `==` or `str::starts_with`, /// `str::ends_with` or `std::contains` or other `str` methods. /// /// **Known problems:** None. /// /// **Example:** `Regex::new("^foobar")` /// /// [regex]: https://crates.io/crates/regex declare_lint! { pub TRIVIAL_REGEX, Warn, "finds trivial regular expressions" } /// **What it does:** This lint 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:** `regex!("foo|bar")` declare_lint! { pub REGEX_MACRO, Warn, "finds use of `regex!(_)`, suggests `Regex::new(_)` instead" } #[derive(Clone, Default)] pub struct RegexPass { spans: HashSet, last: Option, } impl LintPass for RegexPass { fn get_lints(&self) -> LintArray { lint_array!(INVALID_REGEX, REGEX_MACRO, TRIVIAL_REGEX) } } impl LateLintPass for RegexPass { fn check_crate(&mut self, _: &LateContext, _: &Crate) { self.spans.clear(); } fn check_block(&mut self, cx: &LateContext, block: &Block) { if_let_chain!{[ self.last.is_none(), let Some(ref expr) = block.expr, match_type(cx, cx.tcx.expr_ty(expr), &paths::REGEX), let Some(span) = is_expn_of(cx, expr.span, "regex"), ], { 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, block: &Block) { if self.last.map_or(false, |id| block.id == id) { self.last = None; } } fn check_expr(&mut self, cx: &LateContext, expr: &Expr) { if_let_chain!{[ let ExprCall(ref fun, ref args) = expr.node, args.len() == 1, let Some(def) = cx.tcx.def_map.borrow().get(&fun.id), ], { let def_id = def.def_id(); if match_def_path(cx, def_id, &paths::REGEX_NEW) { check_regex(cx, &args[0], true); } else if match_def_path(cx, def_id, &paths::REGEX_BYTES_NEW) { check_regex(cx, &args[0], false); } else if 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_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(cast_possible_truncation)] fn str_span(base: Span, s: &str, c: usize) -> Span { let mut si = s.char_indices().skip(c); match (si.next(), si.next()) { (Some((l, _)), Some((h, _))) => { Span { lo: base.lo + BytePos(l as u32), hi: base.lo + BytePos(h as u32), ..base } } _ => base, } } fn const_str(cx: &LateContext, e: &Expr) -> Option { match eval_const_expr_partial(cx.tcx, e, ExprTypeChecked, None) { Ok(ConstVal::Str(r)) => Some(r), _ => None, } } fn is_trivial_regex(s: ®ex_syntax::Expr) -> Option<&'static str> { use regex_syntax::Expr; match *s { Expr::Empty | Expr::StartText | Expr::EndText => Some("the regex is unlikely to be useful as it is"), Expr::Literal { .. } => Some("consider using `str::contains`"), Expr::Concat(ref exprs) => { match exprs.len() { 2 => { match (&exprs[0], &exprs[1]) { (&Expr::StartText, &Expr::EndText) => Some("consider using `str::is_empty`"), (&Expr::StartText, &Expr::Literal { .. }) => Some("consider using `str::starts_with`"), (&Expr::Literal { .. }, &Expr::EndText) => Some("consider using `str::ends_with`"), _ => None, } } 3 => { if let (&Expr::StartText, &Expr::Literal {..}, &Expr::EndText) = (&exprs[0], &exprs[1], &exprs[2]) { Some("consider using `==` on `str`s") } else { None } } _ => None, } } _ => None, } } fn check_set(cx: &LateContext, expr: &Expr, utf8: bool) { if_let_chain! {[ let ExprAddrOf(_, ref expr) = expr.node, let ExprVec(ref exprs) = expr.node, ], { for expr in exprs { check_regex(cx, expr, utf8); } }} } fn check_regex(cx: &LateContext, expr: &Expr, utf8: bool) { let builder = regex_syntax::ExprBuilder::new().unicode(utf8); if let ExprLit(ref lit) = expr.node { if let LitKind::Str(ref r, _) = lit.node { match builder.parse(r) { Ok(r) => { if let Some(repl) = is_trivial_regex(&r) { span_help_and_lint(cx, TRIVIAL_REGEX, expr.span, "trivial regex", &format!("consider using {}", repl)); } } Err(e) => { span_lint(cx, INVALID_REGEX, str_span(expr.span, r, e.position()), &format!("regex syntax error: {}", e.description())); } } } } else if let Some(r) = const_str(cx, expr) { match builder.parse(&r) { Ok(r) => { if let Some(repl) = is_trivial_regex(&r) { span_help_and_lint(cx, TRIVIAL_REGEX, expr.span, "trivial regex", &format!("consider using {}", repl)); } } Err(e) => { span_lint(cx, INVALID_REGEX, expr.span, &format!("regex syntax error on position {}: {}", e.position(), e.description())); } } } }