use rustc::lint::*; use rustc::hir::*; use syntax::ast::LitKind; use syntax::codemap::Span; use unicode_normalization::UnicodeNormalization; use utils::{snippet, span_help_and_lint}; /// **What it does:** Checks for the Unicode zero-width space in the code. /// /// **Why is this bad?** Having an invisible character in the code makes for all /// sorts of April fools, but otherwise is very much frowned upon. /// /// **Known problems:** None. /// /// **Example:** You don't see it, but there may be a zero-width space somewhere in this text. declare_lint! { pub ZERO_WIDTH_SPACE, Deny, "using a zero-width space in a string literal, which is confusing" } /// **What it does:** Checks for non-ASCII characters in string literals. /// /// **Why is this bad?** Yeah, we know, the 90's called and wanted their charset /// back. Even so, there still are editors and other programs out there that /// don't work well with Unicode. So if the code is meant to be used /// internationally, on multiple operating systems, or has other portability /// requirements, activating this lint could be useful. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let x = "Hä?" /// ``` declare_lint! { pub NON_ASCII_LITERAL, Allow, "using any literal non-ASCII chars in a string literal; suggests \ using the `\\u` escape instead" } /// **What it does:** Checks for string literals that contain Unicode in a form /// that is not equal to its /// [NFC-recomposition](http://www.unicode.org/reports/tr15/#Norm_Forms). /// /// **Why is this bad?** If such a string is compared to another, the results /// may be surprising. /// /// **Known problems** None. /// /// **Example:** You may not see it, but “à” and “à” aren't the same string. The /// former when escaped is actually `"a\u{300}"` while the latter is `"\u{e0}"`. declare_lint! { pub UNICODE_NOT_NFC, Allow, "using a unicode literal not in NFC normal form (see \ [unicode tr15](http://www.unicode.org/reports/tr15/) for further information)" } #[derive(Copy, Clone)] pub struct Unicode; impl LintPass for Unicode { fn get_lints(&self) -> LintArray { lint_array!(ZERO_WIDTH_SPACE, NON_ASCII_LITERAL, UNICODE_NOT_NFC) } } impl LateLintPass for Unicode { fn check_expr(&mut self, cx: &LateContext, expr: &Expr) { if let ExprLit(ref lit) = expr.node { if let LitKind::Str(_, _) = lit.node { check_str(cx, lit.span) } } } } fn escape>(s: T) -> String { let mut result = String::new(); for c in s { if c as u32 > 0x7F { for d in c.escape_unicode() { result.push(d) } } else { result.push(c); } } result } fn check_str(cx: &LateContext, span: Span) { let string = snippet(cx, span, ""); if string.contains('\u{200B}') { span_help_and_lint(cx, ZERO_WIDTH_SPACE, span, "zero-width space detected", &format!("Consider replacing the string with:\n\"{}\"", string.replace("\u{200B}", "\\u{200B}"))); } if string.chars().any(|c| c as u32 > 0x7F) { span_help_and_lint(cx, NON_ASCII_LITERAL, span, "literal non-ASCII character detected", &format!("Consider replacing the string with:\n\"{}\"", if cx.current_level(UNICODE_NOT_NFC) == Level::Allow { escape(string.chars()) } else { escape(string.nfc()) })); } if cx.current_level(NON_ASCII_LITERAL) == Level::Allow && string.chars().zip(string.nfc()).any(|(a, b)| a != b) { span_help_and_lint(cx, UNICODE_NOT_NFC, span, "non-nfc unicode sequence detected", &format!("Consider replacing the string with:\n\"{}\"", string.nfc().collect::())); } }